Development of Hydrological and Hydraulic Study of Regulation of Skadar Lake and Bojana River Water...

MONTENEGRIN ACADEMY OF SCIENCES AND ARTS

DEVELOPMENT OF HYDROLOGICAL AND HYDRAULIC STUDY OF

REGULATION OF SKADAR LAKE AND BOJANA RIVER WATER REGIME

IPA PROJECT

Volume I

Approved at the Session of the Presidency of the Montenegrin Academy of Sciences and Arts, 12 September 2014.

Montenegrin Academy od Sciences and Arts reserves all rights. No part of this book may be reproduced in any form without written permission by the publisher.


DEVELOPMENT OF HYDROLOGICAL AND HYDRAULIC STUDY OF REGULATION OF SKADAR LAKE AND BOJANA RIVER WATER REGIME

Volume I

IPA PROJECT

Special editions (Monographies and Studies)Volume 111

AuthorsDr Milan Radulović, dipl. ing Darko Novaković, dipl. ing Prof. dr Goran Sekulić Mirjana Popović, dipl. ing Nevzeta Alilović, dipl. ing

Project leaderProf. dr Goran Sekulić

EditorAcademician Momir Đurović

Podgoricа, 2014

This project is implemented by the Montenegrin Academy of Sciences and Arts and Albanian Academy of Sciences and managed by the Delegation of the European Union to Montenegro and The Delegation of the European Union to Albania.

The manuscript presents results of the first year research.

This project is funded by the European Union

CONTENTS*

GEOLOGIC AND HYDROLOGIC CHARACTERISTICS OF THE MONTENEGRIN PART OF THE SKADAR LAKE BASIN

INTRODUCTION .............................................................................................................. 91. GEOGRAPHICAL POSITION OF THE SKADAR LAKE BASIN .................. 102. CLIMATE CHARACTERISTICS OF THE

SKADAR LAKE BASIN ............................................................................................ 103. HYDROGRAPHIC AND HYDROLOGICAL CHARACTERISTICS

OF THE SKADAR LAKE BASIN ........................................................................... 144. GEOMORPHOLOGICAL CHARACTERISTICS

OF THE SKADAR LAKE BASIN ........................................................................... 175. GEOLOGICAL CHARACTERISTICS

OF THE SKADAR LAKE BASIN ........................................................................... 196. HYDROGEOLOGICAL CHARACTERISTICS

OF THE SKADAR LAKE BASIN ...........................................................................247. ASSESSMENTS OF GROUNDWATER INFLOW

INTO SKADAR LAKE ............................................................................................28REFERENCES ................................................................................................................. 110

STUDY ON CLIMATE AND HYDROLOGICAL FEATURES OF THE MONTENEGRIN PART OF THE SKADAR LAKE BASIN

I CLIMATE FEATURES IN THE AREA OF THE SKADAR LAKE BASIN ..........................................................................119INTRODUCTION .......................................................................................................... 1191. AIR TEMPERATURE ............................................................................................. 1192. THE AMOUNT OF PRECIPITATION ...............................................................120

* Reports given in this book were presented and approved at the Conference on IPA Project “Development of hydrological and hydraulic study of regulation of Skadar Lake and Bojana river water regime”, held on 19–20 June 2013 year in Montenegrin Academy of Sci-ences and Arts, and present results of the first year work on the Project.

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3. THE MAXIMUM HEIGHT OF SNOW COVER .............................................1224. CLOUDINESS AND SUNSHINE.........................................................................1235. THE WIND ...............................................................................................................1236. CONCLUSION ........................................................................................................125

II HYDROLOGICAL FEATURES OF THE SKADAR LAKE BASIN ..........1251. PHYSICAL CHARACTERITICS OF THE SKADAR LAKE BASIN ............1252. HYDROLOGICAL STATISTICS .........................................................................1293. FLOOD FLOW .........................................................................................................1494. ANALYSIS OF LOW FLOW ..................................................................................1535. DETERMINATION OF THE GUARANTEED

ECOLOGICAL DISCHARGE ...............................................................................156REFERENCES .................................................................................................................159

GEOLOGIC AND HYDROLOGIC CHARACTERISTICS OF THE

MONTENEGRIN PART OF THE SKADAR LAKE BASIN

INTRODUCTIONThe development of the Study of geological and hydrogeological characteristics of

the transboundary Skadar Lake region has been planned as one of the activities of the cross-border IPA project “Development of hydrological and hydraulic study of regula-tion of Skadar Lake and Bojana river water regime”, which is being implemented under the auspices of the Montenegrin Academy of Sciences and Arts and the Albanian Acad-emy of Sciences.

The study of geological and hydrogeological characteristics of a part of the catch-ment area of Skadar Lake, which is located on the territory of Montenegro, will be one of the bases for the development of hydrological and hydraulic study for the purposes of consideration of possibilities of regulation of the water regime of Skadar Lake and the river Bojana.

The study presents the geological and hydrogeological characteristics of the part of the catchment area of Skadar Lake, which is located on the territory of Montenegro (Sec-tions 1-7). One of the elements of balance of Skadar Lake is a groundwater inflow that cannot be directly measured. For this reason, special attention has been paid to the areas wherefrom Skadar Lake is recharged by groundwater in order to give as accurate an es-timate as possible. Defining the underground inflow especially in karst terrains is a very complex problem considering that even after extensive research there is still a possibili-ty of error. There are many factors that complicate the definition of the underground in-flow into the lake, but the most serious being not knowing all the locations of ground-water runoff below the lake level and the problem of determining the catchment areas of known karst sublacustrine springs. The groundwater flows into Skadar Lake in the fol-lowing areas:

– at the southwestern edge of Skadar Lake (Section 8.1),– in the Karuč Bay (Section 8.2),– in Malo Blato (Section 8.3),– at the northern edge of the lake by draining the granular aquifer of the Zeta Plain

(Section 8.4), – in Hum and Hot bays (Section 8.5).The following researchers took part in developing the study: Dr Milan Radulović,

graduate geological engineer (The Faculty of Civil Engineering Podgorica) and Darko Novaković, graduate engineer in geology (The Hydrometeorological Institute of Monte-negro). The study development coordinator has been Dr Goran Sekulic, graduate engi-neer in construction (The Faculty of Civil Engineering Podgorica).

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1. GEOGRAPHICAL POSITION OF THE SKADAR LAKE BASIN The catchment area of Skadar Lake is located in the southeastern part of the Dinar-

ides. The following Sections describe the natural characteristics of a part of the Skadar Lake catchment area, which on the Montenegrin territory covers an area of about 4,460 km2. It is the southern part of Montenegro where the following towns are located: Pod-gorica, Nikšić, Cetinje, Danilovgrad and others. Most of the studied area is a typical karst landscape, characteristic of the External Dinarides.

2. CLIMATE CHARACTERISTICS OF THE SKADAR LAKE BASIN

For the purpose of analysis of natural characteristics of the area The Water Manage-ment Master Plan of Montenegro – WMMPM (2001) as well as the 2005 study “Natural Characteristics of Montenegro” have been used.

The climate of this area, in addition to latitude and altitude, is determined by the presence of large bodies of water (the Adriatic Sea, Skadar Lake), deep sea intrusion into the land (Bay of Kotor), moderately high mountainous hinterland near the coastline (Or-jen, Rumija), as well as a number of other factors.

It is an area where the climate is Mediterranean, which means that the area is char-acterized by long, hot and dry summers and relatively mild and rainy winters. Warm summers are particularly characteristic of the Zeta Valley, and it is in this area that

Fig. 1. The geographical position of the catchment area of Skadar Lake on the territory of Montenegro

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the absolute maximum air temperature in Montenegro has been recorded alongside the highest average number of tropical days.

Karst fields, located at higher altitudes (Cetinje and Nikšićko polje) have a much harsher climate.

Montenegrin climate is highly influenced by Genoa cyclone and Syberia anti- cyclone. Under their effect, high atmospheric pressure and temperature gradients are es-tablished throughout the Balkans, especially in the territory of Montenegro.

2.1. AIR TEMPERATUREMean annual air temperatures range from about 9.7 °C (Cetinje) to 15.3 °C (Podgo-

rica). The approximate temperature gradient is relatively high and on average, amounts to about 0.8 °C per 100 m of change in altitude (Fig. 2).

The hottest months are July and August, while January is the coldest. The mean mi-nimum air temperatures range from 4 °C (Cetinje) to 10.7 °C (Podgorica), while the mean maximum temperatures vary between 16.5 °C (Cetinje) and 20.5 °C (Podgorica). The minimum air temperatures in the area can drop below -15 °C, and the maximum air temperature in summer period can rise over 45 °C.

2.2. CLOUDINESS AND SUNSHINE HOURSSouthern parts of Montenegro are considered areas abundant in sunshine. In coastal

areas the annual duration of sunshine is, on average, 2,430 to 2,570 hours, while in the mountainous areas far from the sea it ranges from 1,630 to 1,930 hours. In all regions, July and August are with about 4 to 5 times more sunshine hours than winter months. The longest duration of sunshine is recorded in the summer months, 250-350 hours, whi-le in the winter it is, on average, less than 100 hours, and in some localities it falls to as low as below 50 hours.

The mean annual cloudiness, as opposed to sunshine hours, increases as we move from the south to the north of the country. The lowest values of the average cloudiness have been

Fig. 2. Diagram of the dependence of mean annual air temperature on altitude on the territory of Montenegro (WMMPM 2001)

y = -0.0079x + 15.21

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

0 200 400 600 800 1000 1200 1400 1600

Tsr (

oC)

Z (mnm)

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recorded at the Montenegrin coast, the Zeta-Bjeloplavići Plain and the Nikšić area. The mean cloudiness on the coast ranges from 44 to 47%, it is 48% in Podgorica and 50% in Nikšić. The highest mean annual value of cloudiness has been recorded in mountainous regions, on average, between 56 to 62%. The lowest cloudiness has been measured in July and August, and the highest in December. The least fluctuation in cloudiness during the whole year has been recorded for mountainous areas, while it is much higher at the coast.

2.3. PRECIPITATIONThe geographical position of the territory of Montenegro influences the occurrence of

the four seasons accompanied by four different precipitation regimes. The general picture of the dynamics of air flow over this part of Europe also has a direct impact on the quan-tity and distribution of precipitation. The Western Mediterranean is a single cyclogene-tic area, which directly affects the precipitation regime in Montenegro. The influence of southwestern air flows, which bring with them enough moisture from the Mediterrane-an Sea, is particularly great and important on southern areas during autumn and winter.

The orographic lifting of moist and unstable air from the southwest contributes to an increase the amount and intensity of precipitation. Due to the general Dinaric strike the mountain ranges in the hinterland of the coast, during the prevailing south-westerly flo-ws, provoke the appearance of windward and leeward orographic precipitation. Moreover, such a strike of mountain ranges forms a natural barrier for the influence of the Adriatic Sea on the north, and carrying the characteristics of continental precipitation regime to-wards the southern areas of Montenegro.

The mean annual precipitation, due to these orographic factors, is very uneven and ran-ges from about 1,300 l/m2 in the Ulcinj area to about 5,000 l/m2 on the slopes of Orjen (Fig. 3). Cyclonic activities in the Mediterranean and moist flows from the south quadrant in the winter months and orographic barriers exert an important influence on the far southern, southwestern and southeastern parts of Montenegro which have significantly higher annu-al precipitation than the far northern parts. In record years, precipitation on the slopes of Orjen may reach approximately 7,000 l/m2, which classifies this area as the one with the hig-hest rainfall in Europe. Another area with very high rainfall is Lovćen with over 3,500 l/m2.

In terms of precipitation regimes, we differentiate between the two regimes: the Me-diterranean regime and the moderate continental regimes. The Mediterranean regime is characterized by maximum precipitation in November and December, and minimum precipitation in July and August. The moderate continental regime is characterized by frequent precipitation in the second half of the summer, secondary maximum in Octo-ber and minimum in February.

The mean annual number of days with precipitation in this area is about 115-130. In the wettest months there are on average 13-17 rainy days, and in the driest, the number of rainy days is 4-10. By far the greatest number of days with heavy precipitation occurs in Cetinje – 74 days.

Snow cover is mostly formed at elevations above 400 meters. At elevations above 600 m, snow cover higher than 30 cm can be expected, and at elevations above 800 meters snow cover can reach a thickness of over 50 cm.

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2.4. WIND The characteristics of airflow over the territory of Montenegro are related to macro

atmospheric circulation over wider areas of the region. The system of macro flow over the European mainland generally shows a seasonal character. Currents ranging from north and north-west to south-west and south periodically alternate over southern Europe. The-

Fig. 3. Map of precipitation and the position of the meteorological and hydrological stations in Montenegro (WMMPM 2001)

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se shifts lead to a low position of the polar atmospheric front, the activity of Mediterra-nean depression and a pronounced cyclogenesis as a result of penetration of the Mediter-ranean cold air masses from northerly latitudes. Typical local winds are Bura and Jugo.

3. HYDROGRAPHIC AND HYDROLOGICAL CHARACTERISTICS OF THE SKADAR LAKE BASIN

The waters on territory of Montenegro drain towards two directions: towards the Adriatic Sea and towards the Black Sea. The total size of the Adriatic basin on the ter-ritory of Montenegro is about 6,267 km2, while the total size of the Black Sea basin is around 7,545 km.

The Morača with its tributaries the Zeta, Sitnica, Ribnica and Cijevna, Crnojevića River and Orhovštica as well as numerous small rivers, belong to the Adriatic Sea dra-inage basin, i.e. the Skadar Lake basin. The Morača River near the Vranjina village flo-ws into the Skadar Lake, from which the Bojana River outflows near the town of Ska-dar. The Bojana River on the left side receives a large amount of water from the Drin Ri-ver, and after a short course flows into the Adriatic Sea, near the town of Ulcinj (Fig. 1).

The average mean values of monthly and annual flow of rivers at the hydrological stations in the Skadar Lake basin are shown in Table 1. The highest discharge typically occurs in December and the lowest in July and August.

Table 1. The average perennial values of the mean monthly and annual flows (m3/s) measured at hydrological stations in the basin of Skadar Lake (WMMPM 2001)

Station (river) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year

Pernica (Morača) 27.42 27.83 30.46 49.34 57.51 29.27 9.74 6.59 10.44 25.14 46.58 41.63 30.16

Zlatica (Morača) 79.69 77.03 73.60 90.69 78.41 36.14 9.90 4.61 14.07 43.67 94.88 99.89 58.55

Podgorica (Morača) 214.9 213.3 203.8 236.0 200.5 103.5 40.9 27.1 50.6 124.2 253.9 274.1 161.9

Botun (Morača)* 262,0 234,0 223,0 279,0 215,0 112,0 40,0 17,5 26,6 92,1 279 325,0 175,0

Duklov Most (Zeta) 22.44 23.45 24.84 33.13 23.87 9.6 2.26 1.22 4.09 14.38 30.72 31.95 18.50

Danilovgrad (Zeta) 113.3 140.4 104.8 109.2 79.2 43.3 22.0 15.04 26.35 61.25 122.3 134.7 78.49

Trgaj (Cijevna) 26.94 28.10 26.80 39.52 41.46 22.93 7.85 4.56 8.15 19.06 36.42 36.34 24.86

*series 1956-1976 (Radulović M. et al. 1982)

3.1. SKADAR LAKESkadar Lake is a transboundary lake whose basin covers an area of about 5,490 km2,

of which around 4,460 km2 belongs to Montenegro, or 81.2%. The lake is elliptical, with

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its longer axis of over 26 km in a NW – SE direction and the shorter axis about 12 km long. The lake surface is directly dependent on its water level. At the minimum water le-vel of about 4.54 meters, the lake covers an area slightly smaller than 400 km2 of which 241 km2 belongs to Montenegro, while at the maximum water level of 10.44 m, it covers an area of about 525 km2 of which around 368 km2 belongs to Montenegro. The average water level at the Plavnica gauge station (the period 1948-1991) amounts to 6.52 m. The volume of Skadar Lake at the minimum water level is about 1.75 km3 (0.97 km3 of which is located on the territory of Montenegro), and at the maximum water level the volume of the lake amounts to about 4.25 km3 (2.70 km3 of which belong to the Montenegrin territory) (Table 2). The average depth of the lake ranges from about 4.4 m to 8.10 m.

Table 2. Morphometric parameters of Skadar Lake in Montenegro (Čvorović et al. 2009a)

Level(m)

Area (km2)

Volume(x 106 m3)

%Min surface to max

surface area ratio in %

%Min volume to max volume ratio in %

4.5 240.94 974.19 100.0% 100.0%5.0 263.66 1 101.18 109.4% 113.0%5.5 278.08 1 236.88 115.4% 127.0%6.0 291.50 1 379.93 121.0% 141.6%6.5 315.87 1 532.40 131.0% 157.3%7.0 327.88 1 693.89 136.1% 173.9%7.5 338.41 1 860.93 140.4% 191.0%8.0 347.42 2 032.81 144.2% 208.7%8.5 354.07 2 208.64 146.9% 226.7%9.0 359.26 2 387.35 149.1% 245.1%9.5 364.01 2 568.53 151.1% 263.6%

10.0 367.83 2 751.87 152.7% 282.5%

Skadar Lake receives the largest amounts of water from the Morača River (65.8%), so the lake water level is directly dependent on its inflow. In addition to Morača River, the Crmnica River, Orahovštica River, Poseljanska River, Crnojevića River, Bazagurska River, Karatuna River and others discharge into the lake, and a significant amount of water is derived from short rivers (Plavnica, Zetica, Gostiljska River, Mala Mrka, Velika Mrka, Raičevića Žalica, etc.) which are formed by discharge of granular aquifer of Zeta Plain along its south edge. The lake is largely fed by karstic aquifer which is drained in the form of many sublacustrine springs (sublacustrine springs - vruljas or “okos”), which usually appear along the lake shore. Taking into account that groundwaters have signifi-cantly lower temperature than lake waters, the locations of major sublacustrine springs can be detected by satellite images taken in thermal-infrared spectral range, as can be seen in Fig. 4 (the locations of Raduš and Krnjice springs, represented by shades of blue, can be observed in the image, while it can also be noted that the Morača River brings much colder water into the lake).

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The lake is drained through the Bojana River. About 2 km downstream the lake, the Drin River, which basin covers an area of about 13,000 km2, flows into the Bojana River. In particular, it should be noted that in the past the Drin River drained directly into the sea near the town of Lezha, but in the mid-nineteenth century after a major flood, the river bifurcated, i.e. the Drin was split into two channels, one of which drained into the Bojana. These changes caused the Bojana water level rise as well as the entire lake water level rise. Today, at high water levels, the Drin River slows down the lake outflow and in extreme cases the Drin waters partially drain into the Lake.

The water balance of Skadar Lake is one of the most important hydrological issu-es. Given that this is a transboundary lake, one of the problems is the exchange of data on the water balance elements between the states. Then, quite a long distance of moni-toring stations from the confluence (HS Podgorica, HS Trgaj) may also affect the accu-racy of the water balance, given the facts of the obvious changes in the size of the flow along the watercourse (sinking, discharge). One of the biggest problems is the impossi-bility of quality measuring of discharge of submerged water courses, then groundwater discharge through numerous sublacustrine springs, as well as diffuse outflow from gra-nular aquifer which is the case at the southern edge of the Zeta Plain.

Fig. 4. Temperature map of Skadar Lake, obtained on the basis of Landsat 7 ETM+ satellite image (thermal infrared channel - Band 6.1, resolution 60 m) recorded on April 23, 2000

(Radulovic M. M. 2010)

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4. GEOMORPHOLOGICAL CHARACTERISTICS OF THE SKADAR LAKE BASIN

Radulovic V. (1989) identifies the three major geomorphic units in the Skadar Lake catchment area on the Montenegrin territory (Fig. 5):

– the karst plateau of Stara Crna Gora, Rudine and Banjani, – Skadar Lake depression, the Zeta Plain, the Bjelopavlići Plain, Nikšićko Polje and

the Duga Gorge, and – Ozrinići-Bjelopavlići-Piperi-Bratonožići-Kuči karst plateau.The Plateau of Stara Crna Gora, Rudine and Banjani in its significant part belongs to

the Skadar Lake basin. These are holokarst terrains that are characterized by the diversi-ty of karst forms (karren, sinkholes, karst valleys, poljas, etc.). As for the major surface karst forms Cetinje polje stands out and This part of the karst terrains is characterized by vertical caves, which in some places may have a depth of over 300 m (Lješević 1994). The average elevation of this karst plateau is about 800 m. From this karst plateau, vi-ewed from the northwest to the southeast, the following mountains rise: Njegoš (1,721 m), Vardar (1,123 m), Savino Brdo (1,153 m), Pusti Lisac (1,475 m), Čumajevica (1,062 m), Vranjska Ljut (1,083 m), Kopitnik (1,133 m), Lovćen (1,149 m), Marin Vrh (1,326 m), Sozina (1,182 m) and Rumija (1,593 m).

Ozrinići-Bjelopavlići-Piperi-Bratonožići-Kuči karst plateau extends from the Vojnik Mountain in the northwest to Dečić Hill in the southeast. This karst plateau is higher than Stara Crna Gora, Rudine and Bunjani plateau. This karst terrain has high degree of karstification. There are numerous surface and subsurface karst landforms. Among uvalas (large dolines) there are following: Ponikvička, Međeđa, Gostiljska, Radovačka, Straganička, etc. In this area a larger number of deep canyons were also formed such as the Cijevna, Morača, Mala Rijeka, Mrtvica and Surdup. From this karst plateau the following mountains rise: Palanka (1,942 m.a.s.l.), Vojnik (1,997 m.a.s.l.), Veliki Žurim (2,034 m.a.s.l.), Veliki Zeavac (2,150 m.a.s.l.), Vjeternik (1,283 m.a.s.l.) and Žijovo (2,182 m.a.s.l.).

The mentioned karst plateaus are separated by the long synclinal zone of the Duga Gorge, Niksićko Polje, the Bjelopavlići Valley and the Zeta Plain. This syncline is elon-gated in a northwest-southeast direction. The elevation generally decreases from the northwest, where it is approximately 900 m.a.s.l., to the southeast, where in the Zeta Valley it ranges from 10 to 80 m.a.s.l. Nikšićko Polje, the Bjelopavlićka Valley and the Zeta Plain are filled with clastic material from which level emerge hills such as: Trebjesa (752 m.a.s.l.), Studeničke glavice (679 m.a.s.l.), Kujava (113 m.a.s.l.), Velja Glava (152 m.a-.s.l.), Visočica (153 m.a.s.l.), Spuška Glavica (160 m.a.s.l.), Gorica (131 m.a.s.l.), Ljubović (100 m.a.s.l.), Donja Gorica (102 m.a.s.l.), Dajbabska Gora (170 m.a.s.l.), Srpska Gora (95 m.a.s.l.), Šipčanska Glavica (139 m.a.s.l.), Vranjska Gora (65 m.a.s.l.), etc.

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Fig. 5. Map of major geomorphological units in the Skadar Lake basin according to Radulović V. (1989)

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5. GEOLOGICAL CHARACTERISTICS OF THE SKADAR LAKE BASIN

5.1. HYSTORY OF GEOLOGICAL RESEARCH The Skadar Lake basin belongs to the southeastern Dinarides, whose complex geo-

logical structure has been a subject of numerous domestic and foreign research pro-jects. Geological data on this terrain date back to the nineteenth century and are collec-ted mainly by foreign researchers. Studies of the first researchers are mostly informati-ve and related to the tectonic, stratigraphic and geomorphological data. Among them, it is important to mention: Lipold (1859), Tietzea (1980, 1984), Baldacci (1896, 1889), Has-sert (1895), Kossmat (1924), Nopcsa (1929), Kober (1929), Zuber (1930), Bukowski (1906, 1913, 1926), Bourcart (1926, 1933).

When it comes to local researchers, the first data of the studied area is found in the papers of Cvijić (1899, 1921, 1924), referring to the geotectonic position of the Zeta Pla-in and geomorphological characteristics of the wider area.

After that, starting in the 1930s, this area has been the subject of geological research of our geologists: Luković and Petković, Protić, Čubrilović, Mikinčić and Jovanović. Af-ter the Second World War the following researchers studied the geological characteristic of the are: Bešić (1951, 1959, 1960, 1969), Petković (1958, 1960, 1961), Miladinović (1955, 1957, 1962, 1964), Milovanović (1953, 1955, 1957) and Roksandić (1966). A significant li-terary source is a doctoral dissertation of Miladinović (1964), which focused on the geo-logy and tectonic formation of the mountain Rumija.

All results of previous research related to the geology and tectonic formation of the studied area have been synthesized within the Geological Map of Montenegro 1:200,000 and Guide Book (Mirković et al. 1985), which served as a major base for the analysis of geological characteristics of the studied area.

5.2. GEOLOGICAL COMPOSITIONIn the Montenegrin part of the Skadar Lake catchment area there are Paleozoic,

Mesozoic and Cenozoic rocks (Fig. 6). These are mostly sedimentary rocks, but there are also volcanic rocks.

Paleozoic. Paleozoic rocks are discovered in the region of Nikšić Župa and Gornja Morača. These are mainly Permian sediments represented by sandstone, shale, conglom-erate, quartzite, claystone and marl.

Mesozoic. The terrain of the Skadar Lake catchment area is primarily composed of Mesozoic rocks (Triassic – T, Jurassic – J and Cretaceous – C).

Triassic rocks (T) are, according to the data on the Geological Map of Montenegro 1:200,000 (Fig. 6), represented by:

– Clastic rocks, limestone and marly-sandy limestone (T1) discovered in the area of Nikšić Župa and Crmnica;

– Flysch which includes: conglomerate, sandstone, marl, siltstone and sandy limestone which were discovered in Nikšić Župa and Crmnica (T2

1);

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– Limestone and dolomite represented in the area of Niksić Župa and Crmnica (T2

1);– Middle Triassic volcanic rocks (andesite, dacite, keratophyre, quartz-keratophyre

and rhyolite) that were discovered in Nikšić Župa, Crmnica and Gornja Morača (T2);

– Volcanic-sedimentary facies, which consists of tuffs, tuffites, cherts, bentonite and sandy marly limestone (T2) ;

– Limestone with cherts, which are present in the areas of Sozina, Crmnica and Nikšić Župa (T2

2);– Bedded and massive limestone, dolomitic limestone and dolomites of the Middle

and Upper Triassic, which have a large distribution in the Morača, Gračanica, Orahovštica and Crnojevića River catchment areas (T2,3; T3).

Within the catchment area of Skadar Lake, Jurassic rocks (J) are represented by:– Carbonate sediments (ammonite and lithiotis limestone, which are presented in

the mountains Vojnik, Vjetrenik, Žujova, Rumija and Sozina (J1);– Bedded, thick-bedded and massive limestone presented in the mountain areas of

Vojnik, Rumija and Sozina (J2);– Bedded, thick-bedded and massive limestone (shallow water and reef

sedimentation), which were discovered at the edge of Malo Blato, Meoc, Lovćen, Banjani and Mrtvica and Morača canyons (J2+3; J2,3; J3).

Cretaceous rocks (K) are represented by: – Bedded and thick-bedded limestone and dolomites of the Lower Cretaceous, with

wide distribution in the Zeta and Morača catchment areas (K1);– Bedded and thick-bedded to massive limestone, dolomitic limestone and dolomite

of the Upper Cretaceous, which are dominantly distributed in the basin of Skadar Lake (K2

1, K22, K2

3);– Cretaceous-Paleogene flysch, which consists of breccia, conglomerate, sanstone

and sandy-marly limestone, which is presented in the upstream part of Morača River catchment area (K, Pg).

Cenozoic. Within the catchment area of Skadar Lake, sedimentary rocks of Paleogene, Neogene and Quaternary also have a certain distribution.

Paleogene (Pg) is represented in this area by flysch that was discovered within a narrow zone stretching from Kuči, through the Zeta Valley and Nikšićko Polje and the Duga Gorge. Paleogene flysh is consisted of marl, claystone, sandstone, breccia and conglomerate (Pg).

Neogen (Ng) has little distribution within the catchment area of Skadar Lake. These sediments are represented by sand and clay with interbeds of lignite. Neogene sediments were confirmed by drilling in the Zeta Plain, at the northwest edge of Skadar Lake (Gostilj, Tuško Polje) where below Quaternary sediments, clayley sands and coalish clay were detected.

Quaternary sediments (Q) are represented by the glacial, glaciofluvial, limnoglacial, diluvial and alluvial sediments.

21

5.3. TECTONICSTectonics of external Dinarides has often been interpreted differently by different

authors. Their opinions usually conflicted in terms that some advocated for the presence of regional overthrusts (Nopcsa 1911; Kober 1915; Roksandić 1966; Miljuš 1972), while

Fig. 6. Excerpt from the Geological Map of Montenegro 1: 200,000 (Mirković et al. 1985)

22

others claimed that the external Dinarides are built up from only minor reverse faults and folds (Ruten 1938; Bešić 1948, 1951, 1952, 1956, 1959; Milovanović 1950, 1954).

Upon completion of the Geological Map of Montenegro (Mirković et al. 1985), most authors accept the regional division of Montenegro into four geotectonic zones: Par-ahton (Adriatic-Ionian) zone, Budva-Cukali zone, Visoki Krš zone, and Durmitor zone (Fig. 7). Since there have already been considerable disagreement among authors deal-

Fig. 6. (Continuation) The Legend of the Geological Map of Montenegro 1: 200,000 (Mirković et al. 1985)

23

ing with this complex problem, and since none of the established models provides a complete explanation of all relations and phenomena in this area, the above-mentioned division should not be always strictly adhered to.

The Skadar Lake basin terrain belongs mainly to the geotectonic zone of the Visoki Krš, while a small part belongs to the Budva-Cukali and the Durmitor tectonic zones.

Fig. 7. Basic Tectonic Map of Montenegro (based on the Geological Map of Montenegro 1:200,000)

A. Adriatic-Ionian zone (Parathion);

B. Budva-Cukali zone;

C. Visoki Krš zone;

D. Durmitor zone;

LEGEND

C1. Stara Crna Gora tectonic unit;

C2. Kuči tectonic unit;

D1. Sinjajevina, Durmitor, Bjelasica and Komovi Tectonic units;

D2. Ćehotina tectonic unit;

D3. Lim tectonic unit.

24

The geological structure of the Visoki Krš zone contains Mesozoic carbonate sedi-ments, Permian and Lower Triassic clastic sediments, Anisian and Paleozoic flysch sediments, volcanic rocks of the middle Triass, Miocene lacustrine sediments and Qua-ternary clastic sediments. As part of the Visoki Krš zone, two structural units are devel-oped, which Bešić (1948) called Stara Crna Gora unit and Kuči unites.

Stara Crna Gora structural unit covers the area between the coastal zone and the Zeta-Skadar depression that is the synclinal area of the Zeta Valley – Nikšiko Polje – the Duga Gorge. There are few complex folds. This area is geomorphologicaly represented by spacious karst plateau of Katunska Nahija (average altitude is about 800 m.a.s.l.), which is extended between the coastal part and the Bjelopavlići Plain. From karst plateu some high montains rise (Orjen, Bijela Gora, Njegoš, Somina, Zla Gora, Pusti Lisac and Garač). The aforementioned anticline area changes, towards the northeast, into the syncline of Zeta, Bjelopavlići, the Nikšićko polje and the Duga Gorge. In this part of the terrain, there are series of narrow horizontal and inclined folds, and reverse faults with steep dips flattened towards the southwest. The general strike of these reverse faults is NW-SE.

The Kuči structural unit is pushed up from north and northeast over the Stara Crna Gora structural unit along the steep reverse fault plane. It covers the area of the moun-tains Žijovo, Vjeternik, Prekornica, Maganik, Lola, Žurim and Vojnik. It is built mainly of Mesozoic carbonate rocks and the Cretaceous-Paleogenic flysch.

On the overall explored area, which partly belongs to the Stara Crna Gora structural unit and partly to the Kuči structural unit, faults are far more numerous than folds. The most prominent fault is a reverse fault that separates these two structural units.

With ruptures of the Dinaric orientation there is a frequent occurrence of tectonic movement over reverse faults (both local and regional movements), while in the rup-tures of other orientations (northeast-southwest), there is also a horizontal component of movement.

Generally, the tectonic formations of the Stara Crna Gora structural unit and Kuči structural unit are quite analogous, with complex structural relations that can manifest through numerous faults and folds intersections.

6. HYDROGEOLOGICAL CHARACTERISTICS OF THE SKADAR LAKE BASIN

6.1. HISTORY OF HYDROGEOLOGICAL RESEARCHGenerally, hydrogeological researches are recent, i.e. their starting after the Second

World War. Below is an overview of only some of the research that has made the most significant contribution to understanding the hydrogeological characteristics of the area.

The hydrogeological characteristics of the whole territory of Montenegro were for the first time discussed in the paper A Sketch of the Hydrogeological Provinces of Yugo-slavia by Stepanović (1957).

In the period 1962-1966 these terrains were subjected to regional hydrogeological research within the hydrogeological study of Montenegro and Herzegovina (Torbarov and Radulović V. 1966). In this paper the Montenegrin territory and Eastern Herzego-

25

vina were divided into a number of small hydrogeological units, and for the whole ter-ritory a hydrogeological map was made to a scale of 1:200,000.

By conducting geological research, Bešić (1969) has made a significant contribution also to understanding of hydrogeological characteristics of Montenegrin karst.

Vlahović (1975) published important data on the hydrogeological characteristics of Nikšićko Polje.

By regional hydrogeological studies of the Skadar Lake (Radulovic V. 1973, 1989) and the South Adriatic basin (Ivanović 1973) an important data were collected about catchment areas, groundwater directions and, physical and chemical charactersitics of groundwater. Within thease researches, the hydrogeological and hydrochemical maps (1:100,000) were created.

Radulovic V. et al. (1973) developed the Hydrogeological map of the Morača catch-ment area upstream from the confluence with the river Zeta, to a scale of 1:50,000. This map is the result of hydrogeological research of the Morača catchment area for purposes of dams and reservoirs constructions.

Important information on the Skadar Lake sublacustrine springs were published by the following authors: Drecun and Ristić (1964), Radulović V. (1972, 1973) and Ristić et al. (1975).

For the purposes of the Spatial Plan of the Republic of Montenegro in 1982, the Hydrogeological Map of Montenegro 1:100,000 was created (Radulovic M., Radulovic V. and Popovic 1982).

In 1982, Burić created the Map of groundwater protection in Montenegro. The is-sue of groundwater protection was dealt with the following authors: Žunjić (1971, 1975), Filipović (1975), Radulović V. (1977), Filipović, Radulović M., Mišurović (1991).

Significant hydrogeological studies were carried out for the purposes of develop-ment of Basic hydrogeological map 1:100,000 for the sheets “Titograd” (Radulović M., Radulović V., Popović 1982), “Bar and Ulcinj” (Radulović M., Popović Z., Vujisić, Novaković 1989) as well as “Kotor” (Marić et al. 1996). As part of these studies numer-ous research projects were carried out such as: hydrogeological mapping, measuring of spring discharges, chemical analysis of groundwater, tracer tests, etc..

Within the book “Karst Hydrogeology of Montenegro”, Radulovic M. (2000) provid-ed an overview of hydrogeological characteristics of the karst terrains of Montenegro.

One of the major bases for exploring the hydrogeological characteristics is the Hydrogeological Map of Montenegro 1:200,000 with Guide Book (Radulović M. and Radulović V. 2004).

Also, numerous detailed hydrogeological investigations have been carried out in this area for the purposes of water supply, hydro-energy, irrigation, protection of water sources, bottling of groundwater and a variety of other purposes, which will be dis-cussed in the following sections.

6.2. SUMMARY OF HYDROGEOLOGICAL CHARACTERISTICSAs mentioned, the main base for exploring the hydrogeological characteristics of

the studied area is the Hydrogeological Map of Montenegro 1:200,000 (Fig. 8) with a Guide Book (Radulović M. i Radulović V. 2004).

26

In the part of Skadar Lake catchment area, which belongs to the territory of Monte-negro, the following types of aquifers are represented:

– Karst aquifer (yellow area on the map, Fig. 8);– Karst-fissured aquifer (green area on the map, Fig. 8); – Fissured aquifer; and – Granular aquifer (blue area on the map, Fig. 8).

Fig. 8. Excerpt from the Hydrogeological Map of Montenegro 1:200,000 (Radulović M. and Radulović V. 2004)

27

Impermeable rocks are classified in a separate group (brown area on the map, Fig. 8).Carbonate rocks, within karst aquifer and karst-fissured aquifer types are formed,

are predominant in the Skadar Lake catchment area (around 73 %). Karst aquifer is generaly recharged by the infiltration of atmospheric waters, but

also it can be fed by sinking streams (Zeta River, Morača River, Mala River, Cijevna River, etc.). Karst aquifers recharged by atmospheric waters takes place mainly in areas with high altitudes, i.e. the karst areas of Stara Crna Gora, Rudine and Banjani karst plateau, as well as on the terrains of Ozrinići–Bjelopavlići–Piperi–Bratonožići–Kuči (Section 5).

Fig. 8. (Continuation) Legend of the Hydrogeological Map of Montenegro 1:200,000 (Radulović M. i Radulović V. 2004)

28

The karst aquifer is mostly drained along the edges of the depressions of Skadar Lake, the Zeta Plain, the Bjelopavlici Plain and Nikšićko Polje, as well as along the canyons of Cijevn Rivera, Morača River, Mala River, Mrtvica River, etc. In thease discharge zones there are numerous hydrological phenomena such as springs, vruljas and estavelles.

Generaly, the karst aquifer in this area has moderate to high hydraulic conductivity. Carbonate rocks represent a hydrogeological conductors and reservoirs for groundwa-ters. The directions of groundwater flow in this area vary. Groundwaters mostly flow from the recharge zone to the nearest erosion basis, i.e. towards the mentioned canyons and depressions, where discharge of karst aquifer occurs via numerous springs.

Groundwater from the karst aquifer has relatively good quality, and according to its an-ion-cation composition they mostly belong to the waters of hydrocarbonate-calcium class.

There are no many fissured aquifers in the Skadar Lake catchment area. They are characterized by significantly poorer conductivity characteristics compared to karst aq-uifers and karst-fissured aquifers.

The main granular aquifer is distributed on the territory of the Zeta Plain. That is a very valuable water resource, especially during the dry period of year (Section 8.4).

Impermeable rocks are represented by clay sediments of the Nikšićko Polje and the Bjelopavlići Plain, flysch sediments, as well as some volcanic rocks distributed in this area. These rocks are usually bottom and side barriers for groundwaters, and in some cases, they may be overlay barriers.

7. ASSESSMENTS OF GROUNDWATER INFLOW INTO SKADAR LAKE

This Section provides assessments of groundwater inflow in the lake (Fig. 9):– From the southwestern edge of the lake (discharge of the Rumija karst aquifer,

Fig. 9a), – In the Karuč Bay (discharge of the karst aquifer of Karuč sublacustrine springs,

Fig. 9b), – In Malo Blato Bay (discharge of the karst aquifer of Sinjac sublacustrine springs,

Fig. 9c), – from the northern edge of the lake (discharge of the granular aquifer of the Zeta

Plain, Fig. 9d), – In Hum and Hot bays (discharge of the karst aquifer of the east edge of the Zeta

Plain, Fig. 9e).In order to provide adequate assessments, the natural characteristics of the select-

ed areas have been analyzed, particularly their geological and hydrogeological charac-teristics (Sections 8.1 – 8.5).

7.1. ASSESSMENT OF THE GROUNDWATER INFLOW FROM THE SOUTHWESTERN EDGE OF SKADAR LAKE

An assessment of the groundwater inflow from the southwestern edge of the lake has been made after applying the KARSTLOP method, i.e. after developing the Map of the effective infiltration (aquifer recharge) for the catchment area of thease southwest subla-

29

custrine springs. Most of the data presented in this Section are the results of the research conducted during the preparation of the doctoral dissertation by Radulović, M. M. (2012).

7.1.1. GEOGRAPHICAL POSITION

The studied area is the catchment area of the sublacustrine karst springs of the south-western edge of Skadar Lake (Fig. 10 and Fig. 11). The total catchment area of the south-western edge covers 185 km2, of which 173 km2 (93.5%) belongs to the territory of Monte-negro, while 12 km2 or 6.5% belongs to the territory of Albania. The state border through this area is only 1.7 km long, and according to the current understanding it coincides with the local watershed so that the two hydro-systems could also be viewed separately.

Fig. 9. Position of the areas in Montenegro where groundwaters inflow into Skadar Lake. a) The zone of sublacustrine springs (vruljas) of the southwestern edge of the lake; b) Karuč Bay; c) Malo Blato Bay; d) Discharge zone of the Zeta Plain granular aquifer; e) Hum and Hot bays.

30

7.1.2. CLIMATE CHARACTERISTICS

The proximity of Skadar Lake is one of factors with the greatest impact on the cli-mate of the area. The studied area is separated from the sea by the mountain ranges of Rumija, but the Skadar Lake basin is open to the sea and thus exposed to direct maritime influences through the lowland regions around the Bojana. Skadar Lake has a similar impact on the climate as the Adriatic Sea, but it is because of its size that its regional influence is considerably weaker, but still significant for the coastal belt. The average January temperature of the lake surface is 6.4°C, and in July it is 24.4°C. Thus, the lake increases the air temperature in winter and decreases it in summer, at the same time affecting the increase in air humidity.

7.1.2.1. AIR TEMPERATURE

For the purpose of analysis of air temperature, the data from the climatological sta-tion “Golubovci” have been used as well as the Map of the Climate Zones of Montenegro 1:300,000 (WMMPM 2001). From Table 13 it can be seen that the average multi-annual air temperature at the climatological station “Golubovci” is 15.3°C, but this value can be adopted only for the areas with lower elevation, i.e. the coastal belt. From the Map of the isotherms of mean annual air temperatures (Fig. 12) it can be concluded that the mean annual air temperature for the studied area is about 10°C.

Fig. 10 Southwest edge of Skadar Lake (Radulović M.M. 2012)

31

Fig. 11. Geographical position of the catchment area (blue line) of the southwestern edge of Skadar Lake

8 km

0

32

7.1.2.2. PRECIPITATION

As the basis for analyzing the rainfall of the investigated area the data from the climatological station “Golubovci” have been used, then the data from the precipitation stations Virpazar, Đuravci, Limljani, Ostros and Ckla, and the Map of Precipitation and Hydrological Stations of Montenegro 1:300,000 (WMMPM 2001). From the Pre-cipitation Map (Fig. 13), by using the method of isohyets it has been calculated that the average perennial precipitation for the southwestern catchment area of Skadar Lake is 2,461mm. The locations of all meteorological and hydrological stations in the studied area have been marked on the map.

Fig. 12. Map of the isotherms of mean annual air temperatures (°C) (period 1949-1991) (WMMPM 2001)

Table 3. Average monthly and annual precipitation (mm) at the precipitation stations Virpazar, Đuravci, Limljani, Ostros and Ckla (observation period 1949-1991) (WMMPM 2001)

Station Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec TotalVirpazar 315 285 236 197 122 78 38 70 157 245 343 351 2437Đuravci 304 278 222 195 122 76 43 57 141 233 345 332 2347Limljani 338 305 252 215 130 78 45 59 159 270 370 376 2597Ostros 341 308 252 214 131 88 52 57 160 267 382 371 2624Ckla 298 286 231 188 119 82 42 59 149 259 346 344 2422

33

Fig. 13. The map of isohyets of the mean annual precipitation (mm) and the position of precipitation and hydrological stations (observation period 1949-1991) (WMMPM 2001)

Fig. 14. The diagram of monthly precipitation (mm) at the precipitation stations: Virpazar, Đuravci, Limljani, Ostros and Ckla (observation period 1949-1991)

0

50

100

150

200

250

300

350

400

450

Jan Feb Mar Apr Maj Jun Jul Avg Sep Okt Nov Dec

P (m

m)

VirpazarĐuravciLimljaniOstrosCkla

34

Based on the data obtained from the climatological station “Golubovci” (Table 14) it is possible to obtain detailed information on the precipitation regime of the Skadar Lake basin; however, for the studied area, the relevant values have been obtained by measurements of rainfall at nearby precipitation stations (Table 3, Fig. 14). Thus, the greatest amount of precipitation occurs during November, December and January, and the lowest rainfall was recorded in July.

7.1.2.3. EVAPOTRANSPIRATION

Given that there are no climatological stations in the catchment area of the south-western edge of Skadar Lake and its surroundings whose data could be taken as repre-sentative for estimation of evapotranspiration using standard methods (Penman, Turc, etc.), it is difficult to provide a quality assessment of the effective infiltration. The value of the effective infiltration, and therefore, evapotranspiration has been estimated by ap-plying the KARSTLOP method, which will be shown in Section 8.1.9.

7.1.3. VEGETATION

The northern slopes of Rumija are mostly covered with deciduous forests especially in higher altitudes (Fig. 15). As altitude declines, the areas covered by forests gradually give way to areas covered with low vegetation typical of karst terrain. A significant part

Fig. 15. Map of the vegetative cover of the catchment area of the southwestern edge of Skadar Lake (based on “CORIN Land cover” maps, 2006)

35

of the basin is covered with pastures, but for the coastal karst belt it can generally be said that it is scarce in vegetation.

7.1.4. SOIL

The Pedological Map of the catchment area of the southwestern edge of Skadar Lake (Fig. 16) shows that calcomelanosol (rendzina) has the greatest distribution. It is present-ed in higher altitudes along the southern and southwestern part of the basin. The cal-

comelanosol thickness is generally below 15 cm (very shallow soil), but in the terrains with lower slope, there is thicker soil, up to 60 cm deep. In the parts of the basin with lower altitudes, there are huge amounts of red soil (terra rossa). Terra rossa is usually less than 15 cm thick, but it can be as much as 60 cm thick.

7.1.5. HYDROGRAPHIC AND HYDROLOGICAL CHARACTERISTICS

Hydrological characteristics of Skadar Lake have been discussed in Section 4, where the data on the surface, volume, depth, water levels, water balance and other hydrologi-cal characteristics of the lake have been presented. Significant hydrological changes oc-

Fig. 16. Pedological map of the southern edge of the Skadar Lake basin (based on the Soil Map of Montenegro 1:50,000, sheet “Cetinje 4”, 1966)

36

curred in the mid-nineteenth century, when there was a sudden rising of the lake level and flooding of numerous sublacustrine springs along the edge.

The river network in the research area is poorly developed. There are a small number of streams where water flows only in the rainy period of the year. Such streams are Čelišta, Mljištica, Kroni and Murićit (Fig. 17), Kroni and Besit and streams around Ostros.

7.1.6. GEOMORPHOLOGICAL CHARACTERISTICS

In terms of geomorphology the studied area could be divided into two geomorphic units (Fig. 19):

– The north-eastern slopes of Rumija, and – The Skadar Lake basin (depression).The northeastern slopes of Rumija (Fig. 18) are made of carbonate rock masses in

which numerous surface and subsurface karst landforms were developed. Rudine and

Fig. 17. The bed of the intermittent stream Coefficient Murićit

37

Banjani Plateau and the Stara Crna Gora Plateau with the slopes of Rumija are one single geomorphological unit (Fig. 15). The most striking surface karst landforms in this region are karren fields that cover a significant portion of the surface of the ter-rain. Sinkholes (dolines) and uvalas are also quite abundant. Their bottoms are usually slightly tilted in the direction of strata dip, i.e., to the northeast. These are some uvalas: Seocka, Bardićka, Livarska, Donjo Briska, Kostanička, and Ostroska.

Bešić (1983) also identifies dry karst valleys in the areas of Ostros, Kostanica, Dragović, Tijana and some surrounding areas. Also, there is a larger number of caves concentrated around Seoca (Ivana cave, Goluspa cave, Požalica cave, Vilina cave, Gol-ubova cave, Rojica cave, Pokrijenica cave, etc.), around Pepić (Čaukova cave, Belovića cave, Nameless cave) and Đujevića cave in the immediate vicinity of G. Briska.

The Skadar Lake basin is a crypto-depression whose floor (at the places of subla-custrne springs) is well below sea level (e.g. Raduš spring). Along the southwest coast of Skadar Lake there are a larger number of smaller islets, usually slightly elongated in the direction of the strata. Some of them are: Starčeva Gorica, Beška, Moračnik, Radac, Tophala, Gorica, etc.

Karst sublacustrine springs (vrulja; or domestic term “oko” – in translation “eye”) along the littoral zone of the lake are geomorphologicaly represented by underwater do-lines through which karst aquifer discharges. Speleo-diving survey performed in 2008 (Szerszeń 2008) included Raduš sublacustrine spring, Krnjice sublacustrine spring and Pokrijenica cave (Seoce).

Cave-diving survey of Raduš spring was performed in July 2008. The Report (Szerszeń 2008) states that Raduš spring was dived to a depth of 76 m, and that it was not the deepest point. There are interesting claims of researchers that in this period

Fig. 18 Karst terrains of the soutwestern edge of Skadar Lake

38

groundwater discharge was not observed. Fig. 20 gives a sketched plan and profile of Raduš spring.

Krnjice spring has been dived to the depth of 20 m, where there is a narrow channel so that go-ing any deeper was difficult. In Fig. 21, a profile sketch of Krnjice spring has been given.

Pokrijenica vertical cave is located in the vil-lage of Seoce in the beckground of Raduš spring. The cave is used for water supply to the local pop-

Fig. 19. Digital elevation model of the Skadar Lake area (Radulović M.M. 2012)

Fig. 20 Plan and profile sketch of Raduš sublacustrine spring; Measuring per-formed by: Uroš Akšamović, Dominik Graczyk, Jacek Olinkiewicz, Andrej Szer szen; drawing: Jacek Olinkiewicz

(Szerszen 2008)

Fig. 21 Krnjice sublacustrine spring; Measurements per-formed by: Uroš Akšamović; Drawing: Jacek Olinkiewicz

(Szerszen 2008)

39

ulation. The Report (Szerszeń 2008) states that the cave was formed along a natural joint and on its bottom there are certain amounts of water. Fig. 22 provides a profile sketch of the cave.

7.1.7. GEOLOGICAL CHARACTERISTICS7.1.7.1. GEOLOGICAL COMPOSITION

As the main base for researching the geological characteristic of the studied area has been the Basic Geological Map 1:100,000 sheet “Bar” with Guide Book (Mirković et al. 1978).

The terrain is built up of Triassic, Jurassic, Cretaceous, Paleogene and Quaternary rocks.

Triassic (T)

Triassic rocks have a wide distribution and are presented as the Middle Triassic (Anisian and Ladinian stage) and Upper-Triassic formations (Fig. 23).

Middle Triassic (T2)Middle Triassic rocks have very little distribution in the studied area. They occur only

in Godinje, in the background of Lučice Bay. They are presented with Anisian (T21) and La-

dinian succession (T22). Also, in a narrower area, there are volcanic rocks – andesite (α T2).

Andesite is made of plagioclase phenocrysts, amphibole, pyroxene and rarely bio-tite. The textures are massive, and the colors range from dark green to dark red. Within the Anisian succession (T2

1) there is massive and bedded red Han-Bulozi limestone. The Anisian succession is overlain by Ladin (T2

2) flat and gray limestone, tuffs and bentonite.

Fig. 22. Sketch of profile and plan of Pokrijenica vertical cave in Seoca (measuring performed by: Dominik Graczyk, Paulina Olinkiewicz; drawing: Jacek Olinkiewicz); Photo: Cave-diver

descending into the cave (Szerszen A., 2008)

40

Middle and Upper Triassic (T2,3)The Basic Geological Map 1:100,000 (Fig. 23) shows that these sediments have wide

distribution in the studied area, making up the western and north western slopes of Rumija starting from Godinje, across Kapa, Bobija, Lonac, Bijela Skala, Rumija summit, Međurječka Mountain and Ćafe Šibri to Štegvaši Mahala. Other lithological parts of this mapping unit are mainly thick-bedded and massive limestone and dolomite. Mas-sive dolomites, within this package of sediments, occur in the form of smaller and larger lenses within the limestone.

The above sediments overlay laminated and bedded limestone and laminated cherts of the Older Ladinian succession, based in bedded limestone dolomitic limestone of the Norian succession. The thickness of the sediments from the Middle and Upper Triassic is about 250 meters.

Upper Triassic (Norian and Rhaetian succession, T32+3)

The sediments of the Norian and Rhaetian successions (T32+3) have a very wide dis-

tribution. They cover the area from Virpazar to the state border with Albania. Hills such as

Obida, Gomiljanica, Igor, Kunji, Selijevica, Granica, Blisnik, Maja Nersana, Maja Smr-dec, Šimbri and Samagari are made of these sediments.

Carnian reef limestone gradually gives way to the sediments of the Norian and Rhaetian successions. As part of this mapping unit, there occur bedded pseudolitic and lumpy limestone, dolomitic limestone and dolomite. Lumpy limestone is mostly whitish and white-yellowish, but there are also limestone parts containing irregular lenses of red marly limestone and small pieces of black limestone.

Jurassic (J) Jurassic sediments have extensive distribution in this area, from the state border

with Albania in the southeast to near Virpazar in the northwest. The Basic Geological Map (Fig. 23) shows that all the three Jurassic sections are presented here: Lias, Dogger and Malm.

Lower Jurassic – Lias (J1)In terms of facies, the Lias is very versatile. It is built by several facies’ sediments

that alternate laterally and vertically. In the Basic Geological Map the following Lias-sic facies have been differentiated: massive and thick-bedded dolomite (J1), bedded and thick-bedded limestone (1J1), bedded and laminated gray limestone and chert (2J1), and oolitic and pisolitic limestone (3J1).

In the area of Dedić and Igor the Lias begins with massive and sterile grain thick-bedded dolomite (J1), which is the lateral synchronous facies of stylolitic limestone and limestone with chert. The thickness of the dolomite facies is 70-100 m.

Bedded and thick-bedded limestone (1J1) are the lateral facies of the above described dolomite facies and the facies of limestone with stylolite and chert.

Bedded and laminated gray limestone and chert (2J1) overlay limestone facies with stylolite and chert. The distribution of this facies is observed from the Albanian border

41

to the Zona Hill. From Kostanje to Zona Hill, the facies of gray oolitic and pisolitic limestone can also be observed (3J1).

Middle Jurassic – Dogger (J2)The sediments of the Dogger overlay conformably over Liassic. It occurs in the form

of an about 150 m thick narrow strip. Three facies have been differentiated on the Basic Geological Map: laminated marly limestone (1J2), thick-bedded and massive crystalline limestone (2J2), and oolitic, pseudolitic and cryptocrystalline whitish limestone (J2).

The facies of thick-bedded and massive reef gray crystalline and cryptocrystalline limestone (2J2) is spread across multiple locations: Lekperi, Boljevići, Alibraimovići, Dragovići and Kroništar. This facies gradually evolves from the Liassic, and also gradu-ally gives way to the malm reef limestone.

The facies of bedded yellowish and marl limestone (1J2) ranges from Kronštar up to Zona Hill. The thickness of these sediments is about 30 m.

In the area Zona and Bogdan hills the brachiopod limestone facies is overlain by the sediments of oolitic, pseudoolitic and cryptocrystalline whitish limestone (J2). This limestone occurs in the form of beds and thick beds.

Upper Jurassic – Malm (J3)Malm sediments occur over a wide area from the Albanian border, along the south-

western shore of Skadar Lake, over Krajina and Eastern Crmnica all the way to Donja Seoca. In these localities, these sediments were developed and represented within three facies: laminated cryptocrystalline limestone and dolomite, massive crystalline lime-stone, as well as bedded, pseudolitic, micro-lumpy and whitish limestone.

The study area is for the most part made of massive crystalline limestone, which extends in the form of a broad band from the Albanian border to Mali Golik. Bedded cryptocrystalline limestone and dolomite also have significant distribution. They oc-cur in the northwestern part of the research area, the area Krnjice and Petrova Ponta. Bedded and pseudolitic and micro-lumpy and whitish limestone are somewhat less pre-sent. They appear as a narrow zone along the southwestern shore of Skadar Lake, the Bobovište to Donji Murići.

Thickness of the Upper Jurassic sediments in the study area is about 500 m.Cretaceous (K)Lower Cretaceous (K1)Lower Cretaceous sediments have very little distribution in the studied area. These

sediments are represented with stratified marl and dolomitic limestone. They are abun-dant in the north-eastern part of the studied area where they build up the hills Božica and Mi Burget. Also, the Upper Jurassic sediments build up the islets of Gorica gat, Tophala, Moračnik, Beška, etc.

The thickness of the sediments at the edge of the lake is about 400 m.Paleogene (Pg)Paleogene sediments also have very limited distribution in the study area. They oc-

cur as isolated groups of breccia, conglomerate and brecciated limestone, overlaying

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Fig. 23. Excerpt from the Basic Geological Map 1:100,000, sheet “Bar” (Mirković et al. 1978)

43

Jurassic limestone marl, limestone chert or the Ellipsactinia reef limestone. These sedi-ments occur in the vicinity of Mali Ćurovići, Briska and Bljac.

Quaternary (Q)

Alluvial sediments (al) have limited distribution in the study area. They occur in the riparian area of Lučica Bay, in the area of Donji Murići and Bes. Alluvial formations are represented mainly by sand and gravel and rarely by alluvial clay.

Deluvial deposits (dl) occur in smaller areas in Gornja Seoca, Reps, Liva, Briska, Martići and Arbneš. Deluvial sediments are composed mainly of limestone pieces that are occasionally mixed with clay and sporadically connected with slope breccia.

Terra Rossa (ts) is also present in the study area, where it occurs mainly through karstified limestone covering the bottom of sinkholes and uvalas. The thickness of red soil (terra rossa) is relatively small, and changes depending on the geographical position. The content of clay particles within the terra rosa is often over 50%.

7.1.7.2. TECTONICS

Regional tectonic characteristics of the study area are described in detail in Section 6.3.

According to the adopted division, the study area, i.e. the northern slopes of Rumija, belong entirely to Stara Crna Gora tectonic unit. The authors of the Basic Geological Map (Mirković et al. 1978) saw the Stara Crna Gora tectonic units in this area as overly-ing the Budva-Cukali zone. On the geological map (Fig. 23) the overthrust fronts can

Fig. 24. Faults map of the southwestern edge of the lake (Radulović, M.M. 2010)

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be traced along the southern slopes of Rumija, from the state border with Albania to Tuđemil, wherefrom it turns in a direction northeast – southwest.

The general strike in the study area is northwest – southeast with a dip towards northeast at an angle of 20 to about 50°.

In the study area a number of faults stretching in different directions can be noted. Some of the faults can have a significant hydrogeological function, as is the case with faults with southeast – northwest strike, along which the groundwater flow towards Raduš and Krnjiice springs (Fig. 24 and Fig. 25 ).

7.1.8. HYDROGEOLOGICAL CHARACTERISTICS7.1.8.1. PREVIOUS STUDIES

Hydrogeological studies are mostly of recent origin, i.e., they began after the Second World War (Section 7.1).

Significant hydrogeological studies were carried out in the period between 1984 and 1988 for the purpose of developing the Basic Hydrogeological Map 1:100,000 of the “Bar” and “Ulcilj” sheets (Radulović M. et al. 1989). As part of these studies numerous investigations were carried out such as: hydrogeological mapping, measuring the yield of springs, chemical analysis of water, artificial tracer tests, etc.

Detailed research for the purposes of investigating the possibilities of abstraction of groundwater for Regional water supply of Montenegrin coast were carried out at Raduš

Fig. 25 Photo-geological map of the surroundings of Luke Bay (left) and Raduš Bay (right) (Radulović M. M. 2010)

45

spring (Avdagić et al. 1989). The largest numbers of studies were focused on a narrower area of the spring in order to determine its yield, physico-chemical characteristics of water, discharge regime, examining the possibilities of abstraction of groundwater, etc.

Speleological investigations of sublacustrine springs of Skadar Lake were carried out in 2008 by Polish and local speleologists (Szerszeń 2008).

The area of the southwestern edge of Skadar Lake has been discussed in detail in the doctoral dissertation by Radulovic MM (2012) where results of recent research were also presented. Part of these results has been presented in this study.

Also, a number of papers have been published on natural characteristics of Skadar Lake alongside many databases containing a number of useful data that complete the picture on hydrogeological issues in this part of the region.

7.1.8.2. KARST AQUIFER DISTRIBUTION

As noted, the studied area is mainly built of carbonate rock masses with fracture and conduit porosity. Thus, the karst aquifer is most prominent in the studied area, while a comparatively small area is covered with a granular aquifer (alluvial and diluvial sediments). The karst aquifer developed within carbonate rocks is represented by the following mapping units (Fig. 23):

– Thick-bedded and massive limestone, dolomite and dolomitic limestone (T21);

– Bedded and laminated limestone with interbeds and nodules of chert (T22);

– Massive and thick-bedded limestone and dolomite (T2,3);– Bedded lumpy limestone, dolomitic limestone and dolomite (T3

2+3);– Bedded and thick-bedded marly and dolomitic limestone (J1);– Bedded and thick-bedded limestone (J1);– Bedded and laminated gray limestone and chert (2J1);– Oolitic and pisolitic limestone (3J1); – Bedded marly limestone (1J2);– Thick-bedded and massive crystalline limestone (2J2); – Oolitic, pseudolitic and cryptocrystalline whitish limestone (J2); – Massive crystalline limestone (J3); – Bedded and pseudolitic and micro-lumpy and whitish limestone (J3); – Bedded dolomites and marly limestone (K1).It can be assumed that the base of karstification is at maximum depth in the area

of Raduš Bay, where there is a discharge of groundwater from the depth of about 70 m below the lake level. On the basis of synchronized measurements (Čvorović A. 2011) of the groundwater level in the Bobovište area (4.77 m) and the lake level (4.74 m), it can be concluded that in the dry period of the year the hydraulic gradient in the discharge zone is extremely low (Fig. 26).

7.1.8.3. AQUIFER RECHARGE

The karst aquifer is recharged from rainfall. An autogenous recharge with diffuse infiltration is dominant. Although, concentrated infiltration occurs at places where

46

smaller streams sink such as the streams of Čelišta, Mljištica, Kroni i Murićit, Kroni i Besit, as well as streams near Ostros.

Since there are no climatological stations in the catchment area or its surroundings whose data could be considered representative, and thera are no possibuilities to per-form high-quality measurements of groundwater discharge through numerous subla-custrine springs along the lake edge, the recharge rate has not been assessed using stand-ard methods (Section 8.1.9.9.).

7.1.8.4. AQUIFER PERMEABILITY

Permeability of this karst aquifer is spatially variable. The highest degree of karsti-fication is related to epikarst zone, while with increasing depth, karstification degree gradually decreases.

Based on the artificial tracer tests carried out in the Ostros area, a connection has been confirmed between shallow hole in Ostros and a karst sublacustrine spring in Va i Šitarit bay. The velocity of artificial tracer was 0.42 cm/s.

According to the calcite saturation index (SIc = 0.11) for a groundwater of Raduš spring, it is possible to conclude that a much slower groundwater circulation occurs on this terrain compared to the surrounding karst terrains of the Stara Crna Gora Plateau (Obod spring, Podgor spring, etc.). Also, by the above-mentioned tracer test a relatively slow groundwater velocity rate has been determined. The slow groundwater velocity is also indicated by the low value of the hydraulic gradient in the discharge area.

Slower flow of groundwater in this case could occur for two reasons: 1. the less developed subsurface karst network, and 2. the high hydrostatic pressure of the lake water due to the great depths of discharge

points (in Raduš Bay the lowest discharge point is located at a depth of over 70 m).

7.1.8.5. DISCHARGE OF AQUIFER

The aquifer is discharged through numerous sublacustrine springs along the edge of the lake (Fig. 27), the largest of which being Raduš and Krnjice springs.

Fig. 26. Hydrogeological cross-section of Rumija Mountain (Radulović M. et al. 1989)

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Raduš sublacustrine spring

Raduš sublacustrine spring is located in Raduš Bay (Fig. 28), at the southern edge of Skadar Lake. The groundwatesr discharge point is morphologically predisposed by an underwater funnel-shaped sinkhole formed in limestone, with a depth of over 70 m and a diameter of more than 130 m. The sinkhole is located along the southwestern shore of Raduš Bay (Fig. 29). The fault that is oriented in a north-south direction and crosses the aforementioned sinkhole can also have a significant impact on the flow direction and discharge of groundwater. On the basis of previous research (Avdagić et al. 1989) it has been assessed that the Raduš spring catchment area is 25.7 km2 (based on topography, etc.) and 24.2 km2 (based on hydrological calculations). In the same study it was as-sessed that the minimum yield of Raduš spring is Qmin = 0.060 m3/s (with a return period 1/20 years), the average yield 1.27 m3/s, while the maximum yield is assessed at about 50 m3/s. When it comes to water quality characteristics, it should be noted that this is low-mineralized, hydrocarbon-calcium class of water. Based on systematic measurements (Avdagić et al. 1989) it has been determined that the values of the physico-chemical parameters of water, with some minor variations, are below or at the level of allowed concentrations.

Fig. 27. Map of sublacustrine springs of the southwestern edge of Skadar Lake (after Radulović V. 1989)

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Fig. 28. Raduš Bay

Fig. 29. Elevation model of the lake bottom in the area of the Raduš Bay (Radulović M.M. 2010)

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Krnjice sublacustrine spring

Krnjice sublacustrine spring (Fig. 30) is located in Luke Bay, near the village Krnjice. The groundwater discharge takes place from the bottom of an underwater funnel-shaped sinkhole. The direction of groundwater towards Krnjice spring can be significantly influ-enced by an observed fault whose strike is north-south (Fig. 24 and Fig. 25). The depth of spring bottom during the summer water level is 24.6 m (Radulovic V. 1989). The catch-ment area of Krnjice spring is entirely built of carbonate rocks (limestone and dolomite).

Other sublacustrine spring at the southwestern edge of the Lake

From Luke Bay to the southeast (to the border with Albania), there is a number of sublacustrine springs, whose names are not known, but the Map of sublacustrine springs (Fig. 27) shows their locations and depths (Radulovic V. 1989). Individual yields of these sublacustrine springs are much lower than the yields of Raduš and Krnjice springs, but for all sublacustrine springs it can generally be said to have large amplitude of fluctua-tions in yield, with some of them even completely dried up in the summer months.

7.1.8.6. HYDROCHEMICAL PROPERTIES OF GROUNDWATER

Groundwater of the studied area are characterized by relatively good physical and chemical properties. Occasionally, during periods of intense recharge, the waters be-come turbid, and occasionally their quality deteriorates.

According to the chemical composition these waters belong to the hydrocarbon-calcium group. Table 6 shows the macro components of the chemical composition of groundwater in Raduš spring.

Fig. 30 . Photos of Krnjice spring in the visible spectral region (left) and in the thermal infrared spectral region (right) taken in order to detect the location of the discharge of cooler

groundwater (Stevanović et al. 2010)

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Table 6. Macro components of chemical composition of groundwater in Raduš spring [Mean values for point 5 (spring bottom) for the period between March 1983 and April 1984.

(Avdagić et al. 1989)]

Sampling point Na+K(mg/l)

Mg(mg/l)

Ca(mg/l)

HCO3(mg/l)

SO4(mg/l)

Cl(mg/l)

T(°C)

Hardness(°dH) pH

Raduš spring 2.96 10.00 42.50 176.90 7.00 5.60 12.10 8.40 7.83

The mean annual temperature of groundwater at Raduš spring is approximately 4°C lower than the mean annual air temperature in the area of Skadar Lake, which could indicate that the karst aquifer is mainly recharged at higher altitudes.

Based on the chemical composition and temperature of groundwater at Raduš spring, calcite saturation index has been calculated, which is SIc=0.11 (calcite is the pre-dominant mineral in the catchment area). The groundwater is saturated with calcite, which could indicate a slower circulation in the catchment area of Raduš spring.

7.1.8.7. CATCHMENT AREA

As previously mentioned, the catchment area of the southwestern edge of Skadar Lake is almost entirely built up of permeable carbonate rocks. In many cases, when de-termining watershed of karst springs, there are many difficulties, especially if detailed hydrogeological research and systematic measurements of water balance elements have not been performed.

The catchment area of the southwestern edge of Skadar Lake is elongated in a north-west-southeast strike. The main discharge points of groundwater occur along the edge of the lake so that the delineation of the catchment area is reduced to determining the spatial position of the southwestern border.

According to the knowledge on the tectonics of the region (Mirković M. et al. 1978), the Visoki Krš tectonic zone, i.e. the Stara Crna Gora tectonic unit overlies the Budva–Cukali zone which mainly consists of impermeable rocks. Thus, the front of overthrust extends across the southwestern slopes, just below the summits of Rumija Mountain. The biggest dilemma in determining the spatial position of the watershed across the area between the Skadar Lake basin and the basin of the Montenegrin coast, is actually a type of watershed, i.e., whether it is a topographic or hydrogeological watershed.

Measurement of the total catchment area of the southwestern edge (with the Al-banian territory) was performed both considering the topographic and hydrogeologi-cal watershed, so that it is assumed that the topographic watershed catchment area is 185 km2, and if measured according to the hydrological watershed, the catchment area amounts to about 200 km2.

The spatial position of the impermeable rock formations and beds dip towards the north-east indicates that the catchment area of the lake can spread out over the south-western slopes of Rumija. However, when performing hydrogeological mapping for the purpose of developing the Basic Hydrogeological Map of the “Bar” sheet (Radulović M. et al. 1998), a large number of contact springs were registered on the western slopes of Rumija (points where flysch and limestone come into contact) the most important of

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which are Duboki Do, Manduke, Kućina, Lektion, Glera, Kurpijeljica, Slakovića springs and Mide spring (minimum yield Qmin = 5 – 100 l/s). It is assessed that individual catch-ment areas of these springs range from 0.5 to 2 km2, a total of about 15 km2, so that the catchment areas of these springs occupy the limited area of south-western slopes of Rumija, from the reef to the discharge place, i.e. to the contact between flysch and limestone.

Therefore, it can be said that in this area we generally speak of the topographic wa-tershed, with slight local variations (Fig. 11). So, the surface of the catchment area on the territory of Montenegro is approximately 173 km2.

The watershed extends from Virpazar over the Besac Hill (101 m) , M. Vis (330 M.), Vis (507 m), Šušnjata Glavica, Konik (424 m), Kapa (m), Gorijuk (797 m), to Pjaždol (933 m.), wherefrom it continues towards Tor (888 m), and further over Lonac (1004 m), binding down to Čukurela (1119 m), over Široke Strane (1185m), and Kunor (999 m) to Čorotoj (976 m) wherefrom the watershed over Čugogolin climbs up to M Rumija (1468 m) and to the very top of Rumija (1595m), continuing towards Brison (1435m) over M. Kozjak (1371m), Kozjak (1427m), Golo Brdo (1312m ), Debelin (1205 m) to Liponjak (1209 m), wherefrom it climbs down the hilltops of Maja e Rahit (951 m), Maja e Gat, Maja Traš (918 m), Šimri (916 m), Breg Bušatm (811 m), Maja e Rahit, Samagarija (746 m), all the way to the border with Albania and further over the clearly marked peaks of Taraboš (595 m) to the places where Bojana flows out of the lake.

7.1.9. RECHARGE MAP OF THE SW EDGE OF SKADAR LAKE AND THE CALCULATION OF THE GROUNDWATER DISCHARGE

Within the aforementioned study (Radulović M.M. 2012) a previously calibrated KARSTLOP method was applied in this area (Radulović M.M. et al. 2012; Radulović M.M. 2012). The method was applied in order to obtain the Map of effective infiltration (the recharge map), calculate the mean annual effective infiltration on the catchment area, and make an assessment of the groundwater discharge which taking place through a number of sublacustrine springs along the lake edge.

7.1.9.1. KARSTIFICATION MAP (K)

For the purposes of making a Map of the degree of surface karstification (Fig. 31) the existing topographic maps were used, alongside digital elevation models, ortho-rectified satellite images (Quick Bird, Spot) resolution of about 2.5 m, aerial images, etc.

For the purposes of creating a Map of subsurface karstification speleological data on the investigated caves were used (Lješević 1980; Szerszeń 2008), alongside the results of previous studies on the discharge and quality of groundwater regime (Avdagić et al. 1989), as well as data obtained by artificial tracer tests (Radulovic M. et al. 1989).

On the Map of the subsurface karstification, zones of about 200 m around each investigated speleological object were first drawn (Pokrijenica cave, Trnovica cave, Gol-ubova cave, Šuplja rock, Pepićka cave, Ćafa Pusa cave, Briska cave, etc.) as well-known as around known swallow holes. The rest of the catchment area was assessed on the basis of

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indirect parameters. For this catchment area the maximum adopted value of sub-factor is Ksf1 = 4. This value was adopted on the basis of assessments of the maximum (Qmax = 50 m3/s) and minimum (Qmin = 60 l/s) yields of Raduš spring (Avdagić et al. 1989). By hydrogeological mapping, tracer velocity was found v = 0.42 cm/s, so that, according to the established categorization (Radulović M.M. et al. 2012; Radulović M.M. 2012) the subfactor Ksf2 has a value of 2. Based on the mean chemical parameters (Avdagić et al. 1989) the calcite saturation index of groundwater was calculated and it amounts to SIc = 0.11. Given this value and knowing the average length of groundwater path in the catch-ment area (1-4 km), the sub-factor Kpod3 value is obtained and it amounts 1.

The map of the degree of karstification (K) is obtained by overlying the surface karstification map (Ksf) and the map of the subsurface karstification (Kss).

The Map of the degree of karstification (Fig. 31) shows that the largest part of the catchment area of the southwestern edge of the lake belongs to the category with me-dium degree of karstification (K>2-3).

7.1.9.2. MAP OF ATMOSPHERIC CONDITIONS (A)

The map of atmospheric conditions (A) is obtained by overlying the Map of Alti-tudes (A1) over the Map of the intensity of solar radiation (A2).

Fig. 31. Karstification map (K) of the catchment area of the SW edge of the lake (Radulović M.M. 2012)

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Altitude map (A1) is obtained based on the ASTER Digital Elevation models. Map of the intensity of solar radiation (A2) was also obtained on the basis of a digi-

tal elevation model using the software package Surfer. For the elevation of the sun the adopted value is α = 47.6 °. The resulting digital map A2 consists of two categories. The largest part of the catchment area to the category with the value A2 = 1, while the rest (mainly represented by the north side of the hills) belongs to the category A2 with a value of A2 = 5.

The map of atmospheric conditions (A) (Fig. 32) shows that the largest area belongs to the category with unfavorable atmospheric conditions for the process of groundwater recharge.

7.1.9.3. MAP OF SURFACE RUNOFF (R)

Given that in the entire catchment area there is no permanent surface water, the complete catchment area has the value of R = 5

Fig. 32.Map of atmospheric conditions (A) of the catchment area of the SW edge of the lake (Radulović M.M. 2012)

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7.1.9.4. SLOPE MAP (S)

The slope map of terrain (S) is obtained based on the ASTER Digital Elevation Model, which is converted by an appropriate tool into a slope map on which the sur-face is categorized in 5 categories: a slope less than 5°, 5-15°, 15-25°, 25-35° and over 35° (Fig. 33).

7.1.9.5. TECTONIC MAP (T)

Map of tectonics (T) was obtained by overlying the Map of the fault density (Tf) and Map of the dip of strata (Td).

For the purpose of creating the fault density map (Tf), a Fault traces map 1:100,000 was first developed by analyzing satellite images (Fig. 24). On the fault density map (Tf) areas are delineated according to the established categorization (Radulović M.M. et al. 2012; Radulović M.M. 2012), with the surfaces categorized according to the length of faults per unit of surface (km/km2).

Map of dip of strata (Ts) is obtained based on the data on the strata dips showed on the Basic Geological Map 1:100,000 of the sheet “Bar”.

Tectonic map (T) (Fig. 34) shows that the largest area is occupied by terrains be-longing to the category of medium influence of tectonics to the process of groundwater recharge.

Fig. 33. Slope map of the the catchment area of the SW edge of the lake (Radulović M.M. 2012)

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7.1.9.6. LITHOLOGICAL MAP (L)

Lithological map has been created on the basis of the data presented in the Basic Geological Map, sheet “Bar”, scale 1:100,000. A map (Fig. 35) illustrates that almost all catchment area can be categorized into fairly favorable to highly favorable influence of lithology on the process of groundwater recharge.

7.1.9.7. MAP OF OVERLYING LAYERS (O)

Soil map (O1) is based on the Pedological Map 1:50,000 sheet “Cetinje 4”. Terrain categorization was conducted based on type of soil and its depth.

Geological cover map (O2) is based on Basic Geological Map 1:100,000 sheet “Bar”, as well as on topographic and geomorphological data.

Overlying (pedological and geological) layers map (O), illustrates that the major part of the catchment area is covered by a highly permeable layers (Fig. 36).

7.1.9.8. PLANTS MAP (P)

Plants (Vegetation) map (P) is based on digital CORINE Land Cover Maps. Five categories of vegetation covers have been identified. Fig. 37 illustrates that the influence of vegetation on effective infiltration in the catchment area is diverse.

Fig. 34. Tectonic Map (T) of the catchment area of the SW edge of the lake (Radulović M.M. 2012)

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Fig. 35. Lithological map (L) of the SW edge of the lake (Radulović M.M. 2012)

Fig. 36. Map of overlying layers (O) of the SW edge of the lake (Radulović M.M. 2012)

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7.1.9.9. RECHARGE (EFFECTIVE INFILTRATION) MAP (IEF)

Final Recharge map (Ief) has been made by combining the eight previously pre-sented maps, on the basis of the algorithm devised beforehand (Radulović M.M. et al. 2012; Radulović M.M. 2012). Terrains of the southeast edge of the Skadar Lake basin have been classified into nine categories on the basis of effective infiltration expressed as percentage (%) of water from precipitation which recharge the aquifer. The map (Fig. 38) illustrates that catchment area are very diverse when it comes to their potential for effective infiltration.

Obtained results imply that the background area of the strongest sublacustrine springs in the southwest edge of the lake (Raduš and Krnjice springs) has the highest potential for effective infiltration. The terrains of the central part of the catchment area, which is drained by the temporary springs of smaller yields, have a bit lower potential for infiltration. The far southeast and far northwest region of the catchment area, with almost no springs at all, show the lowest values of effective infiltration.

7.1.9.10. ASSESSMENT OF GROUNDWATER DISCHARGE

One of the goals of applying KARSTLOP method was an assessment of mean an-nual effective infiltration for this catchment area. Based on that value, by balance cal-

Fig. 37. Vegetation map (P) of the SW edge of the lake (Radulović M.M. 2012)

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culations it was possible to assess the groundwater discharge which occurs through nu-merous sublacustrine springs along the southwest edge of the lake.

The statistical analysis of the Digital Effective Infiltration Map (Ief) has indicated that the average effective infiltration for the catchment area is Ief = 68.5 % (Radulović M.M. 2012). Since that the mean annual precipitation for this area is known, it has been calculated that the effective infiltration is 1,686 mm. Therefore, for the catchment area of 173 km2, the mean annual discharge of groundwater through all springs (from the Mon-tenegrin part) is Q = 9.25m3/s (Table 7).

Table 7. Water balance elements for the catchment area of the SW edge of Skadar Lake on the territory of Montenegro

Catchment area A (km2) P (mm) Ief (%) Q (m3/s)Southwest edge of Skadar Lake 173 2461 68.5 9.25

A – size of catchment area; P – mean annual precipitation; Ief – effective infiltration (recharge rate); Q – mean annual discharge of groundwater.

7.2. ASSESSMENT OF GROUNDWATER INFLOW INTO THE KARUČ BAY

The assessment of groundwater discharge in the Karuč Bay is mostly besed on previ-ously conducted hydrogeological study (Zogović et al. 1992), carried out for the purpose

Fig. 38. Map of effective infiltration of catchment area of the SW edge of Skadar Lake (Radulović M.M. 2012)

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of finding optimal springs for regional water supply system of Adriatic coast. Further-more, the Recharge map of catchment area of Karuč springs (Radulović M.M 2012) has been presented at the end of this Section, providing the results almost identical to the results obtained in the previous studies. Prior to revealing the water balance elements of the Karuč Bay catchment area, in the following Sections will be presented a detailed description of natural characteristics of this area (Radulović M.M. 2012).

7.2.1. GEOGRAPHIC POSITION

The Karuč Bay is situated at the northwest edge of Skadar Lake, between the valley of Rijeka Crnojevića and Malo Blato Bay. There are a lot of sublacustrine springs in the Bay, which make the Bazagurska River. The catchment area (Fig. 39) of these springs covers the area of Lješanska Nahija, in the northeast of the catchment area of Crnojevića River, which borders with it. Main road Podgorica-Cetinje goes through this area, as well as a large number of regional roads connecting the existing settlements (Župa Do-brska, Češljari, Kosjeri, Štitari, Đinovići, Bokovo, etc.).


In addition to all the important factors that affect the climate characteristics of this part of the terrain (latitude, altitude, position of high mountains, etc.), particular em-phasis should be put on the impact of Skadar Lake.

Since there are no climate stations in this catchment area, air temperature for the catchment area of the Karuč Bay can be analysed on the basis of the data collected from the climate station “Cetinje” (Table 9). Mean perennial air temperature at that station is 10 °C. However, the realistic expectation is that the air temperature in the Karuč Bay is higher, since this area covers terrains with considerably lower altitude.

Table 9. Mean monthly and annual air temperatures (°C) at climate station “Cetinje” (WMMPM 2001)

Station Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg.Cetinje 0.8 1.7 4.7 9.0 13.7 17.5 20.1 19.5 15.3 10.1 5.8 2.4 10.0

Data from the climate station “Cetinje” and precipitation station “Karuč” (Table 5.10) may be taken into account when analyzing precipitation; however none of these stations provides highly reliable data. Mean perennial amount of precipitation meas-ured at climate station “Cetinje” (650 m.a.s.l.) is 3,214 mm, and at precipitation station “Karuč”, (10 m.a.s.l.) precipitation amounts to 2,033 mm. The amount of 2,700 mm is believed to be mean perennial amount of precipitation in the Karuč Bay catchment area (average altitude of the catchment area is about 500 m). This amount was also used before in water balancing of this karst aquifer (Zogović et al. 1992). The table below indicates that the highest precipitation occurs from October to April, whilst July and August are the driest months.

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Table 5.10. Mean monthly and annual amounts of precipitation (mm) at climate station “Cetinje” and precipitation station “Karuč” (WMMPM 2001)

Station Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg.Cetinje 402 373 326 248 161 100 65 90 189 314 482 466 3214Karuč 243 229 188 156 102 66 39 61 140 222 310 277 2033

Fig. 39. Geographic position of the Karuč Bay catchment area

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Average evapotranspiration for the Karuč Bay catchment area is assessed by us-ing CMB (Chlorine Mass Balance) method (as well as KARSTLOP method, which will be discussed later on). Mean annual concentration of Cl- ion at closest climate stations „Podgorica” and „Cetinje” is 3.657 mg/l, and 3.648 mg/l respectively. The results of 12 chemical analyses of groundwaters carried out during hydrogeological study (Zogović et al. 1992), indicate that the average concentration of chlorine in groundwater is 5.175 mg/l. Effective infiltration assessed by using CMB method is 70.5 % (1,904 mm), i.e. evapotranspiration ET = 29.5 % of waters from precipitation (796 mm). Evapotranspira-tion value assessed before by using Turc method is 26.37 % (Zogović et al. 1992).

7.2.3. VEGETATION

The map of vegetation cover (Fig. 40) indicates that forests and transitional areas (woodland –scrub) have a dominant distribution in this catchment area. Forests in this

Fig. 40. Map of vegetation cover in the Karuč Bay catchment area (based on CORINE Land cover maps, 2006)

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area are represented by deciduous trees, with no conifers at all. Low scrubs occur in form of bushy vegetation, well developed in the littoral zone of the terrain. Pastures also cover a significant part of the area, mostly in big depressions and along the dry karst valleys. Arable agricultural land is rare. Only the soil at the bottom of sinkholes and uvalas, where potatoes and vine are often grown, is arable.

7.2.4. SOIL

The area is mainly covered by calcomelanosol (rendzina) which overlays carbon-ate rocks (Fig. 41). In general, the thickness of calcomelanosol ranges from 15 to 30 cm (shallow soil), but deeper calcomelanosol, up to 60 cm deep, occupies the terrains with lower slope. Part of the catchment area with lower altitudes (southeast part) is charac-terized by significant distribution of laterite clay (terra rossa). Thickness of terra rossa ranges from 30 to 60 cm, but shallow terra rossa, not deeper than 30 cm, may occur too.

Fig. 41. Pedological map of the Karuč Bay catchment area (based on Pedological Map of Montenegro, 1: 50 000, sheets “Cetinje 1”and “Cetinje 2”, 1970)

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There is a great number of sublacustrine springs (vruljas) in the Karuč Bay, the most significant being Karuč, Volač and Žurovo springs (Fig. 50). This karst aquifer makes Bazagurska River, mostly submerged by the waters of Skadar Lake.

Hydrometric section “Bazagur” controls all waters reaching the Karuč Bay, and the authors of the Final Report on Hydrogeological Research (Zogović et al. 1992), on the basis of hydrological measurements in this section and section “Karuč”, as well as on the basis of water balance assessment, reached the conclusion that the minimal recharge amounts to around 2.5 m3/s, medium recharge amounts to around 7 m3/s, and maxi-mum recharge amounts to 25 m3/s.


Two local geomorphological units may be identified in this part of the terrain (Fig. 42):

– the highland terrains,– the Skadar Lake basin (depression). The Karuč Bay catchment area belongs to Stara Crna Gora karst plateau. Of all the

surface karst landforms, numerous as they are, the dry valley of Karučka River is of sig-

Fig. 42. Digital elevation model of wider area of the Karuč Bay catchment area (Radulović M.M. 2012)

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nificant importance (Radulović V. 1989). The bottom of this dry valley is characterized by occurrence of a large number of dolines and temporary swallow holes (Fig. 43). The map of distribution of karren fields and karst depressions (Fig. 43) provides a rough es-timate of this area, characterized by high degree of karstification, considering the high density of these karst landforms.

There are a lot of caves in this area, as well. Some of them are with water so they can be used to provide water supply to this region. There are three such vertical caves west from Lainje: Nova cave, Mala Jarčica cave and Velja Jarčica cave (Radulović M. et al. 1979).

It is a well-known fact that the area of Skadar Lake lies in a crypto depression, since certain portions of its floor sink below the sea level. It is karst springs that are the deep-est points of the lake, so e.g. the deepest part of the Karuč Bay is the bottom of Karuč spring, 19.5 m deep, as measured during the low water levels (Radulović et al. 1982). The lowest part of Skadar Lake floor is Raduš spring, whose depth goes even beyond 70 m. So, karst springs are actually underwater dolines through which karst aquifers are discharged.

7.2.7. GEOLOGICAL CHARACTERISTICS 7.2.7.1. GEOLOGICAL COMPOSITION

The basis for introducing the geological composition of the Karuč Bay catchment area is the Basic Geological Map, 1:100,000, sheets “Kotor” and “Titograd“, with Guide Books (Antonijević et al. 1969; Živaljević et al. 1967).

The whole catchment area is made of carbonate rocks (limestone and dolomite). These rocks are marked as Triassic, Cretaceous and Quaternary depositions on the Basic Geological Map (Antonijević et al. 1969; Živaljević et al. 1967) (Fig. 45).

Triassic (T). When it comes to Triassic depositions, only sediments of the Upper Triassic (T3) may be found, represented by thick-bedded to massive dolomites, dolomitic limestones and limestone. These rocks occur in the southeast part of the catchment area.

Fig. 43. Map of distribution of karren fields (left) and karst depressions (right) in the Karuč Bay catchment area

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Jurassic (J) Jurassic depositions have a dominant distribution in the Karuč Bay catchment area. They are marked on the geological map as the Lower, Medium and Upper Jurassic.

Lower Jurassic (2J1, 1J1). Sediments of Lower Jurassic are made of thick-bedded, often

oolitic limestone, dolomite, marly limestone and chert. Red limestone with ammonite are categorized as the lower part of Liassic (1J1) while the other marly-chert layers with brachiopods are categorized as the upper part of Liassic (2J1). Thickness of these layers ranges up to 600 m. Sediments of lower Jurassic are distributed in the south and west part of the catchment area (Fig. 44).

Medium and Upper Jurassic (J2+3, J2,3). Medium Jurassic beds are very often scarce in fossils thus, according to the Basic Geological Map authors, it would be impossible to separate them from Upper Jurassic formations. They are represented by bedded and thick-bedded, compact and oolitic limestone. The thickness of these beds ranges from 400 to 500 m. These beds have a wide distribution in the catchment area and their strike is northwest-southeast along a wide area, from Kosmatica to Karuč.

Upper Jurassic (J32, 3). Upper Jurassic sediments are represented by limestone with

interbeds of dolomite. They are distributed in the stretch of area along the same strike as the aforementioned and described rocks, form the Karuč Bay to Grabova Glavica. The thickness of these sediments is estimated at about 200 m.

Fig. 44. Bedded to thick-bedded limestone (1J1)

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Fig. 45. Excerpt from Basic Geologic Map 1:100,000, sheets “Kotor” and “Titograd” (Antonijević et al. 1969; Živaljević et al. 1967)

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Cretaceous. Cretaceous deposits are distributed in the northeast part of the catch-ments area where, according the geological map, they were developed during the Lower and Upper Cretaceous (K1, K1, 2, K2

2). These sediments lie concordantly over Upper Ju-rassic deposits.

Lower Cretaceous (K1). Sediments of Lower Cretaceous are represented by limestone, marly limestone, dolomitic limestone and dolomites. The underlying stratum (bottom) of these sediments is made of deposits from Upper Jurassic (J3

2, 3), while the top is made of carbonate rocks of undivided Cretaceous unit (K1, 2). The thickness of these sediments is about 400 m.

Lower and Upper Cretaceous (K1,2). This unit is represented by dolomite, dolomitic limestone and limestone. The top of these rocks is made of Upper Cretaceous sediments. The thickness of these depositions is about 350 m.

Upper Crateceous (K22). Sediments of this mapped unit do not have a wide distribu-

tion in the Karuč Bay catchment area. They occupy the area in the far northeast part of the catchment. They are represented by dolomites, dolomitic limestone and limestone. The thickness of these rocks is estimated at about 500 m.

Quaternary (Q) Quaternary sediments are virtually absent from this area, except for laterite clay (terra rosse) which fills the bottoms of dolines, uvalas and dry karst valleys.

7.2.7.2. TECTONICS

Karst terrains of the Karuč Bay catchment area belong to geotectonic zone of Visoki Krš, more precisely, the Stara Crna Gora tectonic unit (Antonijević et al. 1969; Živaljević et al. 1967).

This area is characterized by a large number of faults with different strikes. The most renowned fault is Češljari fault, which plays a significant hydrogeological func-tion. Češljari fault, whose strike is northwest-southeast, can be traced from Orah, over Štitari, Češljari to Meterizi and Grab in the the south. Strata in this area generally strike northwest-southeast, with a dip towards northeast at an angle of 15-20o.

Hydrogeological characteristics of this area depend, to a great extent, on tectonic characteristics of the region. Groundwater flow takes place mainly along joints and faults. Also, the discharge point of these karst aquifer (Karuč springs) is tectonically predisposed.

7.2.8. HYDROGEOLOGICAL CHARACTERISTICS 7.2.8.1. PREVIOUS RESEARCH

Sections 6.1 and 7.1 provide an overview of the most important regional geological and hydrogeological studies carried out in this area. The following lines provide a brief overview of some of the detailed studies with exclusive regard to the immediate sur-rounding of the Karuč Bay.

This area has been presented in the Basic Hydrogeological Map of 1:100,000, sheets “Titograd” (Radulovic M. et al. 1982) and “Kotor” (Maric et al. 1997). As part of the research, for the purpose of creating these maps, the artificial tracer tests have been car-ried out and their results proved to be highly valuable in delineating watersheds.

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A detailed hydrogeological study of the Karuč Bay catchment area was carried out in 1991 and 1992 by Energoprojekt (Zogović et al. 1992) in order to abstract waters for the needs of Regional water supply system for Montenegrin coast. Hydrogeologi-cal study of the catchment area, detailed hydrogeological and engineering geological study of the spring zone, bathymetric survey, hydrometeorological studies, hydrological measurements (setting limnigraphs), temperature logging, diving study and water qual-ity analysis were carried out as part of this extensive study.

Additional studies were continued in 2005 for the needs of Regional water supply system, when the alternatives of water abstraction from Karuč spring and Bolje Sestre spring were compared. After a detailed hydrogeological study in the area of Bolje Sestre spring (Radulovic M. et al. 2006; Stevanovic et al. 2007 a, b, c, M. Radulovic et al. 2007), this spring was selected for the regional water supply of Montenegrin coast.

Speleodiving studies of subclasturine springs in Skadar Lake were conducted in 2008 (Szerszeń 2009). The study also included the exploration of sublacustrine springs and caves in the Karuč Bay.

From 2007 to 2009, the Bathymetric survey of Skadar Lake floor was conducted, including the survey of the Karuč Bay bed as well.

Two deep exploratory boreholes (300-350 m deep) were drilled in the area of Župa Dobrska in 2009-2010 for the purpose of groundwater bottling, and these boreholes registered the level of karst aquifers of the sublacustrine springs of Karuč at a depth of about 175 m (Čvorović A. 2010).

Thermal imaging of Karuč spring was carried out in in August 2010 (Stevanovic et al. 2010) by using a special camera to detect temperature anomalies in thermal-infrared spectral area. The recorded images were used to register the main point of groundwater discharge in the Karuč spring.

7.2.8.2. DISTRIBUTION OF KARST AQUIFER

Since only carbonate rocks (Section 8.2.7.1.) with fracture and conduit porosity are distributed in the catchment area, the karst aquifer has a wide distribution in the plan. Groundwater was registered by exploratory drilling in Župa Dobrska, about 5 km up-stream from aquifer discharge point, i.e. from the Karuč Bay.

Based on results obtained by drilling in Župa Dobrska (220-255 m.a.s.l.) it was noted that carbonate rocks in this area reach the depths even greater than 350 m. Borehole B1 was drilled to a depth of 301 m, and borehole B2 to a depth of 352 m. Groundwater level in borehole B2 is located at an elevation of about 47 m.a.s.l., i.e. at a depth of about 176 m. Borehole B2 registered frequent occurrence of conduits and more fractured zones at intervals 170-180 m, 220-240 m and 270-350 m (Čvorović A. 2010).

7.2.8.3. AQUIFER RECHARGE

Since there are no impermeable rocks in the Karuč Bay catchment area, this area is exclusively characterized by autogenous recharge. Atmospheric waters are infiltrated rather quickly after rainfall events, usually not far from the place where they reach the

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surface. However, in cases when water from rainfall is locally collected through less permeable rocks, a concentrated infiltration through swallow holes occurs.

Disintegrated and suspended in the subsurface zones, the catchment area of Karučka Rijeka is characterized only by swallow holes with temporary sinking, which can be di-vided into two main groups (Radulovic M. et al. 2010):

– swallow holes at the contact of dolomite and limestone, – swallow holes formed in dolins (sinkholes).The first group of swallow holes was formed at the contact of permeable and less

permeable rocks. Waters flowing over the terrain made of dolomite soak sinks as soon as they encounter more permeable rocks, which are, in this part of the terrain, represented mainly by karstified limestone.

The second group of swallow holes was formed in temporary flooded sinkhole whose bottom is covered by clay (terra rossa). Such are swallow holes in sinkholes be-low Grabova Glavica and in Lakinje (Fig. 46). Waters which run down the steep slopes during the rainy season of a year, over dolomite, flood sinkholes for a short period of time and open swallow holes in clays which hide the ground of the terrain made of limestone. Those are usually funnel-like depressions on the edges and in the bottom of sinkholes. The distinctive feature is that over time water forms deposits of loose material and backfills already formed swallow holes and opens new ones, changing their shape and position in the field.

Effective infiltration value in the Karuč Bay catchment area has been assessed by using CMB method and it amounts Ief = 70.5%, i.e. 1903 mm.

Fig. 46. Sinkhole with swallowhole in Lakinje

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7.2.8.4. SPELEOLOGICAL DATA

The most common subsurface karst landforms in this area are small pits and caves, with and without water, formed mainly in dolomite (Radulovic M. et al. 1979), such as the ones that appear west of Lakinje (Nova cave, Mala Jarčica cave and Velja Jarčica cave). The most extensive speleological study of this area was conducted as part of the study for development of the Basic Hydrogeological Map sheet “Titograd” 1:100,000 (Radulovic M. et al. 1979). Significant results have also been obtained through speleo-logical study of the Karuč Bay (Szerszeń 2008).

Nova Jama cave, which is actually a cave with water, was formed in thick beds of dolomite. Water in this cave may be reached by taking the existing stairs. The very cave gradually narrows and after 7 m continues in siphon, so it is not possible to follow the dipping canal which continues in the north-west direction any further. Dolomite beds are intersected by a fault crack, along which this phenomenon with elements of dip 210/55 has formed.

Fig. 47. The plan of Volačka cave (Szerszen 2008)

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Mala and Velja Jarčica caves were formed in thick beds of dolomitic limestone along the ruptures in the terrain. The depth of water in these pits is 4.80 m and 4.72 m, respec-tively. According to local inhabitants, an extraction has been performed in the pit Velika Jarčica for the purpose of filling a tank in Lakinje. In 24 hours the water was completely drained, and as a result of that, pit Mala Jarčica dried up as well, which is a proof of underground connections between these two pits. However, the level of water in the pit Nova jama remained at the same level as before extraction, which suggests that this pit is fed by water by means of channels that are not connected to each other, indicating a specific role dolomite plays in this part of the terrain. Since these are the only natural hy-drogeological phenomena with water in the vicinity of Lakinje, local residents use them for drinking. During the rainy season of year water from the referred pits runs out. Upon coming into contact with limestone, water flows downward, and continues its journey through underworld and probably feeds the intermittent source Vlahinje located at low-er elevation in Lainje. The body of water which does not sink into limestone flows over bedded dolomite towards the existing sinkhole where it dives into formed swallowholes.

Only one out of numerous caves detected in pure limestone is with water. It is a pit in Prisoj, a hamlet near Progonovići. It is formed on a flat plateau in karstified bedded limestone. During the dry spell of a year, depth to water level in this pit is about 12 m (Radulovic M. et al. 1979).

Fig. 48. The plan of Baleškovica cave (Szerszen 2008)

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Volačka cave (Fig. 47) and Baleškovića cave (Fig. 48) are among noteworthy subsur-face karst landforms as well. Volačka cave has been explored in a length of about 200 m, and to a depth of about 48 m (Szerszeń 2008). Baleškovića cave has been explored in a length of about 30 m (Szerszeń 2008).

7.2.8.5. AQUIFER PERMEABILITY

Groundwater flows mainly along privileged directions marked by larger faults. Wa-ter circulation towards Karučko and Volačko spring takes place through karst channels which are lowered deep below the point of discharge, which indicates that these are typical vauclusian springs (ascending type of spring). Explored caves situated below the groundwater level are characterized by fairly spacious channels based on which it can be deduced that this is very permeable karst aquifer.

Fig. 49. Map of hydraulic connections between swallow holes and springs obtained through artificial tracer tests

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Also, based on data derived from exploratory boreholes (wells) drilled in Župa Dobrska (Čvorović A. 2010), the conclusion may be drawn that this is a relatively well karstified and fractured aquifer. Based on the same data it can be deduced that the base of karstification is at relatively great depth (greater than -130 m below sea level). Drilling did not register impermeable rocks, so it is difficult to determine whether the bottom of karst aquifer is made, of compact carbonate rocks or impermeable sediments (e.g. flysch sediments), as is the case with karst aquifer of Crnojevića River.

A great number of artificial tracer tests have been carried out in the wider area of the Karuč Bay. Only Uranine (Na-fluorescein) was used as the tracer. The results of ex-periments have helped in determining spatial location of watersheds in the catchment area of Karuč springs.

Valuable data in delimiting the catchment area of Karuč springs from the catch-ment area of Oraška Jama spring was the result of a tracer test performed in the sinking streams from spring Orluina in Čevo, at which the hydraulic connection with Oraška Jama spring has been determined.

Table 10. Table of hydraulic connections obtained through artificial tracer tests conducted in previous studies (Radulović V. et al. 1973; Ivanović et al. 1973; Radulović M. et al. 1982)

No Tracer injection point

Date tracer injected

Tracer appearance

point

Date tracer appeared

Elevation difference

Distance(m)

Tracer speed (cm\s)

1.Swallow hole below Grabova glavica, Štitari

02. 12. 1977. Oko Volač, the Karuč Bay 05. 12. 1977. 510 12875 5.4

2.Swallow hole Lainje, Župa Dobrska

10. 12. 1977.Đurovo oko, oko Karuč, spring Volač

29. 12. 1997. 300 62000.650.650.67

3. Swallow hole Brežine 18. 12. 1978.

Kaluđerovo oko, Malo Blato

20. 12. 1978. 230 3950 2.3

4. Swallow hole Orulina - Čevo 31. 03. 1970 Oraška jama 03. 04. 1970 805 13750 5.34

5. Swallow hole in Cetinjsko polje 15. 03. 1934

Spring of Crnojevića rijeka

17. 03. 1934 598 7000 4.05

6. Swallow hole inCetinjsko polje 23. 10. 1935


25. 10. 1935 598 7000 4.74

7. Borehole C-4, Cetinjsko polje 09. 07. 1973


28. 07. 1973 614.98 8550 0.52

8. Borehole C-2, Cetinjsko polje 15. 03. 1970


29. 06. 1970 622.5 8850 0.25

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The results of a tracer test performed in the swallow hole in the Lainje have been used in division the catchment area of Karuč vrulje from the adjacent catchment area of Crnojevića River. The connection between swallow hole Lainje and Karuč springs has been detected. Tracer has appeared in three locations, in Đurovo spring, Karuč spring and Volač spring.

Based on results of four tracer tests performed on the catchment area of Karuč springs, the average tracer velocity has been calculated, and it amounts 1.84 cm/s.

More comprehensive data on all the tracer tests carried out in the wider area of the Karuč Bay have been presented in Table 10, and determined connections between shal-low holes and springs have been shown on the map (Fig. 49).

7.2.8.6. DISCHARGE OF GROUNDWATER

Significant amounts of groundwater are discharged in the Karuč Bay through fol-lowing sublacustrine springs: Karuč spring, Volač, Đurovo spring, Studenac, Radiševo spring, Žabino spring, Grivo spring, Bazagurska spring, etc. The water from Karuč Bay outflows through Bazagur River.

The position of karst springs (vruljas, okos) has been presented in a bathymetric map (Fig. 50). The bathymetric map (Čvorović M. et al. 2009) shows the levels of the lake floor in the area of the Karuč Bay, but since it is a bathymetric map in scale 1:10,000, made on the basis of a certain number of measured points, maximum depths, usually located in discharge points have not been covered by undertaken surveys.

Majority of aquifers are discharged at greater depths below the lake level, as is the case with Karuč spring (Fig. 51) whose maximum depth during summer months is about 20 m. The main place of discharge is at the very bottom of the spring. During the summer months discharge is represented by a zone of much colder water, as registered by thermal imaging (Fig. 51; August, 2010) (Stevanovic et al. 2010)

Karst channels through which water reaches the discharge zone are lowered to depths greater than the depth of Karuč spring (Fig. 52). Such is the case with karst chan-nels of the Volač spring which descend to depths greater than 50 m.

The Karuč Bay is the main place of discharge of explored karst aquifer. As men-tioned before, all waters are outflowed through Bazagur River whose mean annual dis-charge is 7 m3/s. Discharge of Bazagur River in hydrological minimum is 2.5 m3/s, and in hydrological maximum it is about 25 m3/s (Zogović et al. 1992).

For years, water abstraction from Karuč spring has been one of alternative solu-tions to regional water supply of Montenegrin coast, but upon multi-criteria analysis, the Bolje sestre spring, located at the western edge of Malo Blato, has been chosen.

The catchment area of Karuč springs is characterized by complete absence of surface water, except for minor temporary streams the only notable being Vlahinje stream situ-ated in the doline of Lakinje.

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Fig. 50. Bathymetric map of the Karuč Bay (Čvorović et al. 2009) with locations of springs

Fig. 51. A photograph of Karuč spring in a visible spectral range (left) and a photograph of Karuč spring in thermal infrared spectral range which indicating a temperature anomaly i.e. main

point of groundwaters discharge (right) (Stevanović et al. 2010)

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7.2.8.7. HYDROCHEMICAL PROPERTIES OF GROUNDWATER

Waters of Karuč springs are generally of good quality. The biggest problem is the occasional microbiological contamination.

Based on chemical composition, waters match those from karst aquifers, in which prevalent anion are hydrocarbonate, and prevalent cation is calcium. Based on general hardness, waters belong to moderately hard waters (classification by Cult). The pH val-ue of these waters is about 8 (Table 11).

Table 11 Macrocomponents of chemical composition of water from Karuč spring [Average values, Zogović et al. 1992]

Sample taken in

Na+K(mg/l)

Mg(mg/l)

Ca(mg/l)

HCO3(mg/l)

SO4(mg/l)

Cl(mg/l)

T(°C)

hardness(°dH) pH

Karuč springs 2.73 7.34 47.95 95.51 3.72 5.88 11.70 8.21 7.95

Waters in Karuč springs have a temperature of 11.7 °C. This is a relatively low water temperature, since the Karuč Bay is located at an altitude of 9 m.a.s.l., where a mean an-nual air temperature is about 16 °C. The aforementioned temperatures may indicate that the explored karst aquifer is recharged at much higher altitudes. Also, low and stable temperature of groundwater may indicate that the groundwater flow to Karuč springs takes place at depths beyond the reach of outside temperature influence.

Fig. 52. Hydrogeological section from Oštro Brdo to the Karuč Bay (Radulović M. M. 2011)

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The saturation index of primary mineral is SId = - 0,66. Such a low value may imply a relatively rapid water circulation, i.e. a well-developed network of karst channels.

7.2.8.8. CATCHMENT AREA

The Karuč Bay catchment area covers about 116 km2. Spatial position of watersheds in the Karuč Bay catchment area is determined on the basis of geological, hydrological, geomorphological and hydrological data, as well as on the results of previously con-ducted artificial tracer tests.

The Karuč Bay catchment area borders the catchment area of Malo Blato (Sinjac springs) in the northeast and the north, the catchment area of Oraška Jama spring in the northwest (the Municipality of Danilovgrad), the catchment area of the Bokakotorska bay in the west and the catchment area of Crnojevića River in the south and southeast.

The border of the Karuč Bay catchment area spreads towards northwest over V. Vez-ca (445 m.a.s.l.), V. Trštenik (422 m.a.s.l.) Crna glava (337 m.a.s.l.), Leperići (425 m.a.s.l.), Gojani (478 m.a.s.l.), Ilijino brdo (702 m.a.s.l.), Klobučnik, Komansko brdo, Orije (699 m.a.s.l.), Grabove kose, Velje točilo (919 m.a.s.l.), Stupina glava (1101 m.a.s.l.), Stavor (1241 m.a.s.l.), to Dužički krš (1055 m.a.s.l) where watershed starts to turn to southwest over Prisojna Planinica, V. Čelinca (1316 m.a.s.l.), Oporac (1131 m.a.s.l.), Ložički Vrh (1072 m.a.s.l.) to Balbakani (1114 m.a.s.l.) where watershed continues towards southeast over Jabučki vrh (1103 m.a.s.l.), Morigrad (918 m.a.s.l.), Dobrištik (928 m.a.s.l.), Bokvice, Jarebički vrh (622 m.a.s.l), Vesela straž (628 m.a.s.l.), Visina (603 m.a.s.l.), Krek (574 m.a.s.l.), Visoka glavica (408 m.a.s..l.), Viš (312 m.a.s.l.), Božureva glavica (262 m.a.s.l.) all the way to the Karuč Bay.

7.2.8.9. WATER BALANCE ELEMENTS OF KARST AQUIFER

Since the karst aquifer is recharged only by atmospheric waters, only mean annual effective infiltration value is required as an input water balance element. The yield of all springs in the Karuč Bay i.e. the mean annual discharge of Bazagurska River is taken as an output water balance element. Table 12 shows water balance elements obtained from previous studies presented in the text above.

Table 12 Table of water balance elements in the Karuč Bay catchment area

Hydrometric station A (km2) P (mm) Ief (%) Q (m3/s)

Bazagur 116 2700 70,5 7,0A – size of catchment area; P – mean annual precipitation; Ief – effective infiltration; Q – mean annual discharge.

Nearly the same value of the average effective infiltration for the Karuč Bay catch-ment area has been obtained by applying KARSTLOP method (Fig. 53).

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7.3. ASSESSMENT OF GROUNDWATER INFLOW INTO MALO BLATO BAY

The following subsections provide a brief overview of natural characteristics of wid-er area of Malo Blato Bay (Radulovic M. et al. 2005; Stevanovic et al. 2007a,b,c; Radu-lovic M. et al. 2007), as well as data on groundwater inflow from this area, based mainly on an analysis of previous documentation (Radulovic M. et al. 1979).

7.3.1. GEOGRAPHIC POSITION AND HYDROGRAPHIC CHARACTERISTICS

The basin of Malo Blato is located at the far northwestern edge of Skadar Lake. The area of Malo Blato is enclosed by slopes of Bobija (433 m.a.s.l.) and V. Vezca (447 m.a.s.l.)

Fig. 53. Effective infiltration map (Ief) of the Karuč Bay catchment area obtained by KARSTLOP method (Radulović M.M. 2012)

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on the west, the territory of village Sinjac and slopes of Velji Vrh (418 m.a.s.l.) on the north, and limestone crest on Kolozub – Lepina ploča on the east (Fig. 54). Streams of Šegrtnica and its only distributary Biševina enclose the basin of Malo Blato on the south and make the Karatuna River, which upon receiving waters of Bazagur River, flows into the Crnojevića River, near Ploče.

Fig. 54 Geographic position of Malo Blato Bay

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Climate characteristics of this part of the terrain are affected by its proximity to the sea, longitude, altitude and spatial position of hilly mountainous area surrounding Skadar Lake, and thus the basin of Malo Blato.

Climate characteristics of karst hinterland of Malo Blato are very similar to pre-viously described climate characteristics of the Karuč Bay catchment area, since the surface in both areas is the same and both catchment areas are located at approximately same altitude. Mean annual air temperature should be around 13 °C, and mean peren-nial precipitation about 2,700 mm (Zogović et al. 1992).


Wider area of Malo Blato is characterized by development of karst landforms in highly karstified Jurassic and Cretaceous limestone (typical holokarst). Karren and dolines are most common surface karst landforms, while the most common subsur-face landforms are caves, such as a cave next to Radinovići Estate (Spasojeva cave) and Šutonića cave in Grbavci (Fig. 55).

The most distinctive subclasturine karst forms in Malo Blato are karst okos (vrul-jas), which are usually underwater sinkholes, reaching depths of over 10 meters. It is in sinkholes where the point of discharge of karst aquifers is located at. Sublacustrine

Fig. 55. Šutonića cave in Gornji Grbavci (photo: Radulović M.M.)

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springs (vruljas) will be discussed in greater detail in the Section addressing hydrogeo-logical Characteristics of this area.

7.3.4. GEOLOGICAL AND TECTONIC CHARACTERISTICS

The immediate surroundings and the floor of the Malo Blato basin are composed of (Radulović M. et al. 2005):

– Medium Jurassic (J2) and Upper Jurassic (J3) bedded limestone, dolomitic lime-stone and dolomite;

– Lower Jurassic (K1) limestone and dolomite; – Upper Jurassic (K2) thick-bedded and bedded limestone, bituminous limestone,

dolomite limestone and dolomite; – Quaternary fluvioglacial, alluvial, lacustrine sediments. The general strike of strata is northwest-southeast with a dip towards northeast at

an angle of 10-25o. The terrain is intersected by numerous faults with different strike di-rection, the most significant of which are the faults at the east edge of Malo Blato. Those are mostly faults whose general strike is northeast-southwest and east-west, which di-rect karst aquifer waters towards the Bolje Sestre spring.

The faults between Velja Greda (249 m.a.s.l.) and Kolozub (221 m.a.s.l.), east of Malo Blato, have the same strike direction as the abovementioned faults and mark the tec-tonic contact between bedded limestone (J2) and thick-bedded limestone and dolomit-ic limestone (K2).

7.3.5. HYDROGEOLOGICAL CHARACTERISTICS

Wider karst area around the Malo Blato basin is made of carbonate rocks repre-sented by limestone, dolomitic limestone and dolomite. From a hydrogeological point of view those are highly permeable rocks, characterized by fracture and conduit porosity. Karst aquifer is discharged through strong temporary and permanent karst springs at the edge of the lake and sublacustrine springs situated in the lake floor (Fig. 56).

There is a high number of karst springs and vruljas in Malo Blato, the most sig-nificant of which are springs and vruljas at the north and east edge of Malo Blato: Kaluđerovo spring, Crno spring, Bolje Sestre spring, Brodić spring and Biotsko spring. Waters of all these springs in Malo Blato are discharged through stream Biševina, whose mean annual discharge according to data obtained from short-term measurements at the hydrometric station “Nikolin Mlin” is Qsr = 11.75 m3/s (Radulović M. et al. 1979).

The karst spring with highest yield in Malo Blato is the sublacustrine spring Bolje Sestre, located at the foot of west slopes of Kolozub (221 m.a.s.l.), near the island Kosmač. It is discharged from bedded dolomitic limestone, which dips towards northeast at an angle of 28° (Radulović M. et al. 2005).

During the dry season of a year, waters of this spring are discharged in the wide sec-tion at the level of the lake, and for the most part even under the level of the lake, under pressure from the lake floor (Fig. 57) i.e. from a depth of 7-8 m, as determined by previ-ous measurements (Radulović M. et al. 1979). The minimal yield of Bolje Sestre spring is about Qmin= 2.3 m3/s, as measured by the Hydrometerological Service of Montenegro.

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Water temperature in the dry season of a year, according to data of measurements car-ried out so far, is between 14-15 °C. After detailed hydrogeological studies undertaken in this area (Radulović M. et al. 2005; Stevanović et al. 2007a, b, c; Radulović M. et al. 2007), this spring was connected to the Regional water supply system for Montenegrin coast.

Fig. 56. Excerpt from the Hydrogeological map of wider surroundings of Malo Blato (Radulović et al. 2007)

Fig. 57. Sublacustrine spring (left) and littoral karst spring Bolje Sestre (right) prior to water intake construction (Radulović M. et al. 2007)

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7.3.6. THE CATCHMENT AREA OF MALO BLATO

For the largest part, the catchment of Malo Blato belongs to typical karst terrains, with an inherent and distinct problem of delineating hydrogeological watersheds (Radulović M et al 2007; Stevanović et al. 2007).

Based on prior hydrogeological studies (Zogović et al. 1992), the catchment area of Sinjac spring (springs in Malo Blato) is estimated at about 80 km2.

However, bearing in mind the high measured mean discharge of Biševina River (Qav=11.75 m3/s) and the yield of Bolje Sestre spring (Qmin = 2.3 m3/s), it is clear that sublacustrine springs in Malo Blato, recieve part of waters through subterranean inflow from other catchments.

This conclusion primarily refers to the Bolje Sestre spring. The karst background of the spring, area of Velja Greda, Kolozub and Oblun between Malo Blato i Grbavci, does not cover an area wide enough to recharge this high-yield karst spring.

Based on the results of the studies undertaken so far, it has been determined, with absolute certainty, that this spring receives part of its waters from the east karst hinterland, interstratally from limestone from Jurassic period. Groundwater circulation mostly takes place from east to west at the contact of bedded limestone and dolomite from Jurassic pe-riod, as confirmed by tracer test performed in the borehole B-8 (Radulović M. et al. 2007).

Furthermore, it may be assumed that this spring is partly fed through groundwater from alluvial and glaciofluvial sediments, i.e. from the granular aquifer of the plain land area of Grbavci, which recharge the karst aquifer (Radulović M. et al. 2007).

A bottom of granular aquifer is made of karstified limestone from which ground-water flows towards littoral springs in Malo Blato, as confirmed by the results of tracer injection in the borehole IBG-2, when the connection with Čkanjak spring (located at the north from the Bolje Sestre spring) was proven (Stevanović et al. 2007). The results of tracer tests carried out in 2007, in newly drilled boreholes B-1 and B-8, have indicated that the of groundwater flow direction in this part of the terrain is east-west.

Towards the north, the catchment of Sinjac springs i.e. springs in Malo Blato cov-ers the part of karst terrains of Velji Vrh (418 m.a.s.l.), Goljemadi, Brežine, Podstrane, Staniseljići, Papratnica, Paraci, Buronje, Draževina, all the way to Busovnik and Releza (627 m.a.s.l.).

The connection between Brežine swallow hole and Kaluđersko spring at the north edge of Malo Blato has been proven by artificial tracer test.

7.3.7. WATER INFLOW INTO THE SKADAR LAKE FROM MALO BLATO BAY

Due to complexity of hydrogeological problems, it is not possible to establish the borders of the Malo Blato catchment area reliably, thus the KARSTLOP method was not used for assessing the total yield of sublacustrine springs.

The most reliable data on mean annual outflow of waters from Malo Blato towards the Skadar Lake are the results of short-term hydrometric measurements carried out on river Biševina, (distributary of Malo Blato, Hydrometric station “Nikolin Mlin”), ac-cording to which the mean discharge is Qsr = 11.75 m3/s (Radulović M. et al. 1979).

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7.4. ASSESSMENT OF GROUNDWATER INFLOW INTO THE LAKE FROM THE GRANULAR AQUIFER OF ZETA PLAIN

Through discharge of granular aquifer, formed in the glaciofluvial and alluvial sedi-ments of the Zeta Plain, a large number of short streams are formed at the north edge of the lake, some of which are the Plavnica, Zetica, Gostiljska River, Svinješ, Pjavnik, Velika and Mala Mrka. Conducting hydrological measurements on all these streams is extremely difficult, since diffuse seepage occurs in a wide section. The assessment of granular aquifer discharge, i.e. groundwater inflow into the lake from the north side, is based on results of groundwater mathematical modeling in the area of the Zeta Plain (Radulović M.M. et al. 2010). In the following subsections, before presenting the results of the aforementioned mathematical model, an overview of climatic, hydrographic, geomorphologic, geological and hydrogeological characteristics of this area will be pre-sented (Radulović M. et al. 2010).


The Zeta Plain is situated in the south part of Montenegro occupying an area of about 300 km2. The Morača River, Ribnica River, Cijevna River and Sitnica River run through the Zeta Plain. The capital of Montenegro – Podgorica stands at the confluence of the rivers Morača and Ribnica.

The Zeta Plain is surrounded by limestone hills from the east, north and west side and it is opened towards the Skadar Lake basin from the south side.


Climate characteristics of this part of the terrain are primarily influenced by the proximity of the sea, latitude and elevation and spatial location of hilly-mountainous area surrounding Skadar Lake i.e. the Zeta Plain. The available data from climate sta-tion „Podgorica”, obtained for the time period from 1961 to 2000, and climate station “Golubovci”, for the time period from 1978 to 2000, were used to determine the climate characteristics of wider study area.

7.4.2.1. AIR TEMPERATURE

Air temperature is one of the most significant climate elements, since changes in air temperature conditions affect the changes in other meteorological elements and oc-currences. The Zeta Plain is the warmest part of Montenegro, whereas Podgorica is one of warmer cities of Europe. Mean annual air temperature in Podgorica and Golubov-ci is uniform and it is 15.4 °C and 15.3 °C respectively. The warmest month is July, with a mean temperature of 26.2 °C, and the coldest month is January with temperature of 5.2 °C (Table 13).

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Table 13. Monthly and annual air temperatures in Podgorica for the period from 1961 to 2000 and in Golubovci for the period from 1978 to 2000 (Burić D. et al. 2007)

Sta-tion T °C Months

Jan Feb Mar Apr Jun Jul Aug Sep Oct Nov Dec Annual

PG

Mean value 5,2 6,8 10,0 13,9 23,2 26,2 25,9 21,3 16,0 10,6 6,6 15,4Mean max. 9,9 11,6 15,1 19,1 28,8 32,1 32,1 27,4 21,9 15,6 11,2 20,8Mean min. 1,5 3,0 5,7 9,0 17,6 20,4 20,5 16,5 11,7 6,8 3,0 10,8Abs. max. 19,6 23,6 27,4 30,4 38,6 40,8 41,6 38,8 32,0 26,1 20,8 41,6Abs. min. -9,6 -8,4 -5,6 0,8 8,0 12,2 11,4 6,0 0,0 -4,8 -7,7 -9,6

GOL

Mean value 5,2 6,6 10,0 13,6 22,8 25,8 26,0 21,4 16,3 10,4 6,6 15,3Mean max. 9,8 11,4 15,0 18,7 28,4 31,9 32,2 27,2 21,5 15,1 10,9 20,5Mean min. 0,5 1,9 5,0 8,4 17,0 19,7 19,8 15,6 11,1 5,8 2,4 10,0Abs. max. 18,5 23,0 25,6 28,8 37,0 39,4 41,6 37,7 30,6 24,1 19,7 41,6Abs. min. -12,0 -9,7 -6,0 0,0 9,5 11,8 11,4 8,5 -0,7 -6,0 -7,5 -12,0

7.4.2.2. PRECIPITATION

The annual amount of precipitation and its monthly distribution is one of the main climate characteristics of a place. The amount of precipitation is of significant impor-tance for determining water balance. The explored area is characterized by Mediter-ranean type of annual range of precipitation i.e. maximum amount of precipitation in late fall (November through December) and absolute minimum of precipitation in July. The mean annual precipitation in Podgorica amounts to 1,637.4 mm, while mean an-nual precipitation in Golubovci is a bit lower and amounts to 1,495 mm. The rainiest month is November with the mean amount of precipitation of 240 mm or 14% of an-nual amount of precipitation, whereas the driest month is July with 37.8 mm (Table 14).

Table 14. Monthly and annual amounts of precipitation in Podgorica for the period from 1961 to 2000 and in Golubovci for the period from 1978 to 2000 (Burić et al. D. 2007)

Station Precipita.(mm)

MonthsJan Feb Mar Apr Jun Jul Aug Sep Oct Nov Dec Annual

PGMean value 169 157 147 152 59 38 58 133 173 240 221 1637Abs. max. 381 403 349 340 162 100 185 390 523 639 414 2318Abs. min. 0,5 0,0 10,4 13,8 8 0 4,6 0 0,0 20 36,6 1018

GOLMean value 135 144 132 132 57 26 53 145 169 221 198 1495Abs. max 351 342 314 297 206 91 187 388 495 595 364 2187Abs. min. 1,3 0,2 13,1 11,9 2,9 34 0 0 164 16,7 31,7 958

7.4.2.3. WIND

Northerly wind is the most frequent wind in the annual wind distribution and it amounts to 13.8 % of total wind direction frequency during the year. It blows at an aver-age speed of 3.3 m/s and it reaches maximum speeds to even 40 m/s. Southerly-south-

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easterly wind amounts to 11.1 % and it blows at an average speed of 2.1 m/s. Westerly wind amounts to 1.9 % and easterly wind amounts to 2 %.

7.4.2.4. EVAPOTRANSPIRATION

Evapotranspiration is a complex process marked by water loss through atmospheric evaporation and evaporative water loss through plant transpiration. Potential evapo-transpiration represents the amount of water which may evaporate from a certain area. This value is of significant importance for solving the problem as it takes direct part in water balance of the explored area. Evapotranspiration is directly influenced by tem-perature and it is at its lowest point during winter, while its highest values occur during summer. The calculation of potential evapotranspiration is based on the data from cli-mate station „Podgorica” (Hydrometerological Service of Montenegro) and it has been calculated by using the Penman method and the following equation:

where: ET – evaporation from a surface covered with short grass (mm/day)Δ – slope of the saturation vapour pressure curve (table T-XI; Prohaska, Ristić,

2002)Ra – radiation at the top of atmosphere (mm/day) (table T-XII; Prohaska, Ristić,

2002)n – actual duration of bright sunshine (hours)N – maximum possible duration of bright sunshine (hours) (table T-XII; Proha-

ska, Ristić, 2002)σT4 – back radiation emitted by black surface at the temperature T (mm/day) (ta-

ble T-XII; Prohaska, Ristić, 2002)T – mean temperature, mean value of maximum and minimum temperature

(ºC)U – wind speed (km/da)e – mean morning vapor pressure (mb)es(T) – saturated vapor pressure at the temperature T (mb) (table T-XII; Prohaska,

Ristić, 2002)γ – psychometric constant (0,67mb/ ºC)The values of potential evapotranspiration and its monthly distribution are pre-

sented in the Table 15.

Table 15. Values of potential evapotranspiration for climate station “Podgorica”, computed by the Penman method

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec AnnualMean monthly evapotranspi-ration (mm)

34,5 51,4 84,3 107,8 150,6 183,4 220,9 202,1 130,0 81, 7 45,2 31, 6 1353,2

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The area of the Zeta Plain belongs to the Skadar Lake catchment area, i.e. the Adri-atic Sea basin. Dominant river in wider area is the Morača River with its tributaries: Zeta, Sitnica, Mala Rijeka, Ribnica and Cijevna. Several streams below mountains Ja-vorje and Zebalnica at the elevation of 975 m form the Morača River. Near Zlatica, it enters the Zeta Plain and flows through it all the way to its confluence with Skadar Lake. The amount of water that flows through the Morača watercourse and its tributar-ies varies during the year. Table 1 presents the mean monthly and annual discharge at flow gauge station “Pernica”, “Zlatica”, “Podgorica” and “Botun”.The table shows that discharge values at water gauge station “Botun” during the summer months are lower than those measured at the upstream station “Podgorica”, which indicates that waters in this part of watercourse soak in hydrological minimum. It is a significant amount of water which, in this way, feeds the granular aquifer of the Zeta Plain.

In addition to the Morača River, its tributaries the rivers Zeta, Ribnica, Cijevna and Sitnica are important for determining the hydrographic characteristics of the wider area of study, as they partly feed the granular aquifer the Zeta Plain as well.

The studied problem calls for determining the hydrological characteristics of Ska-dar Lake, which borders the Zeta Plain from the south side (Section 4.1.). Moreover, short small rivers such as Plavnica, Zetica, Gostiljska River, Svinješ, Pjavnik, Velika and Mala Mrka play an important role in feeding Skadar Lake with waters from the granular aquifer.


The wider study area is characterized by two geomorphological units: the area of the Zeta Plain and the area of karst surrounding terrains.

The Zeta Plain is surrounded by hilly-mountainous area from three sides, whereas it gradually turns into the Skadar Lake basin to the south. A number of limestone hills with relatively low height rise from the plain, most prominent of which are Gorica, Ljubović, Srpska and Dajbabska gora, Šipčanička gora etc. According to Bešić (1973), the Zeta Plain is a depression of tectonic origin filled with Tertiary marine sediments and thick Quaternary deposits. The coarsest material with significant participation of conglomerate occurs in the northern part of the plain, while finer fractions of gravel and sand are most dominant in the south part. Impermeable clay sediments are widespread in the southern part of the plain, below glaciofluvial sediments, as confirmed by a bore-hole drilled in Gostilje, which determined the Quaternary thickness to be 88 m. In ad-dition to this, boreholes drilled in Tuško polje (the field of Tuzi) below 85-95 m thick Quaternary sediments, have registered Pliocene sediments represented by clays. Plain elevations gradually decrease from north to south, i.e. from Zagorič where the elevation is over 50 m.a.s.l. to Skadar Lake or Zetski Lugovi where elevations are below 7 m.a.s.l.

Rivers flowing into the Zeta Plain and the Skadar Lake basin have played an im-portant role in shaping the appearance of this area, since they cut their canyons, whose depth at certain points reaches a few tens of meters in tightly packed fluvioglacial sedi-ments.

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Parts of Stara Crna Gora tectonic unit confine the Zeta Plain from the southwest part, while Kuči tectonic unit confine it from the northeast side. These are typical holo-karst terrains represented by numerous surface and subsurface karst landforms: karren fields, dry valleys, gorges, sinkholes, uvalas, poljes, swallow holes, caves, etc.

7.4.5. OVERVIEW OF PREVIOUS GEOLOGICAL AND HYDROGEOLOGICAL STUDIES

In Sections 6.1 and 7.1 we have presented an overview of the most important re-gional geological and hydrogeological studies of this area. The following Section focuses on some of the in-depth studies carried out in the Zeta Plain area.

In spite of numerous papers on geological composition and geomorphological char-acteristics, it may be said that hydrogeological studies of the Skadar Lake basin were not undertaken before the World War II had finished. Those studies were mostly undertak-en with an aim to resolve specific economic tasks, such as determining and establishing the conditions and possibilities of controlling the waters of Skadar Lake, the Bojana and the Drim as well as the Zeta Plain melioration and providing water supply to settlements in the Zeta Plain.

Radulović V. (1989), who in his monograph “The Hydrology of the Skadar Lake Basin” presented numerous data on this area in a neat and organized way, has made a significant contribution to identifying hydrogeological characteristics of the Zeta Plain.

A set of exploratory-piezometric boreholes and wells were drilled in the area of the Zeta Plain during the period from 1970 to 2012 (Ćemovsko Polje, Karabuš, Tuško polje, Zagorič, Dinoško Polje, etc.), aimed at providing drinking and utility water as well as irrigation. More than 20 wells, 70-80 m deep, φ 600 – 800 mm, with total yield of over 2 m3/s, were drilled for the purpose of irrigating vineyard plantation.

Nine 50-meter deep wells were dug in the area of the Aluminium Plant Podgorica with a diameter - φ 800/600 mm and with respective yield of 120 l/s, with small depres-sions ranging from 0.10 to 0.20 m.

A well, 38 m deep, with a capacity of 60 l/s with a depression of 1.2 m, was dug for the purpose of providing water supply to the Golubovci airport, while an 81-meter deep well, φ 500/300 mm in diameter was dug to meet the needs of settlement Milješ.

The report with proposed measures by the State Commission for solving the envi-ronment quality problem of the Zeta Plain and the environmental impact of the Alu-minium Plant Podgorica (M. Burić, A. Mišurović, D. Novaković et al. 1993.) provides certain data on pollution sources in the Zeta Plain catchment area as well as data on environment quality.

Springs aimed at meeting the water supply needs in Podgorica were provided at various locations along the Zeta Plain by digging a group of 50 to 80 meters deep ex-ploratory-exploitation wells (Zagorič, Ćemovsko polje, Milješ, Konik), all of which are a part of Podgorica water supply system.

Zagorič Spring is situated in the settlement having the same name as it north from the Podgorica downtown and it is composed of four wells, φ 500 – 600 mm in diameter and 50–75 m deep. Two pumps with capacity of 100 l/s were installed inside the two

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wells, whereas the capacity of the third well is 75 l/s. The forth well is of recent date (2008) and a pump with capacity of 100 l/s was inserted in it. The elevation at the spring point is 540 m.a.s.l. and water level in the well varies from 27.4 to 31.4 m.a.s.l. This spring provides a total of about 400 l/s to the water supply system of Podgorica.

Water source “Ćemovsko Polje” is located in the field with the same name southeast from the centre of the town, and it is also known under the name “Stari Aerodrom”. This water source is composed of 5 wells, φ 500 – 1000 mm in diameter, 60-80 meters deep, which were successively put into exploitation in the period from 1999 to 2005. The respective yield of these wells is 60 – 110 l/s. This significant spring may provide about 360 – 400 l/s thus during the summer periods water is pumped from all wells, while during winter 2 to 3 wells are exploited.

The “Konik” well is situated in the settlement with the same name in the east part of the town, adjacent to the primary school “Marko Miljanov”, at about 200 m from the course of the river Ribnica. A well with φ 2000 mm in diameter was dug, reaching the depth to 18 m below the terrain surface. Below the depth of the well, a dug well was drilled with a filter construction, φ 325 mm in diameter, reaching the depth up to 40 m. The elevation of the terrain is 54.23 m.a.s.l and the lowest water level in the well, regis-tered so far, is 29.50 m. Minimal yield of the well is about 50 l/s.

The “Milješ” spring is located southeast from the town area in the settlement with the same name. It belongs to the water supply system of Podgorica since it is connect-ed to it by asbestos-cement pipeline with φ 125 in diameter over the Ćemovsko field (Ćemovsko polje). This spring is composed of three wells, with respective capacities of 35 l/s, 20 l/s and 12 l/s and it is possible to tap 65 – 70 l/s from this spring. This spring was developed with an aim to improve water supply of Tuzi, Malesija and Zeta.

Two 40-meter deep wells with a diameter of φ 500/300 mm were dug for the purpose of providing water supply to Morača Sport and Recreation Center. Under the pump ca-pacity of 35 l/s, a drawdown of S = 0.30 m was recorded.

Hydrogeological observations and measuring groundwaters levels were carried out in 1975 aimed at determining the microlocation of groundwaters pollutants south from the Aluminium Plant Podgorica. In addition to these studies, chemical and bacterio-logical analyses on samples taken from the wells in this area were conducted as well. These studies were undertaken by the Montenegrin Institute for Geological Research (S. Ivanović).

Zogović D. provides a set of useful data on hydrogeological characteristics of the Zeta Plain within the hydrogeological study The Possibilities of Groundwaters Utiliza-tion in Irrigation of the Ćemovsko field (“Energoprojekt” 1978).

Popović and Radulović (1985) developed a Study on Groundwaters Reserves in the area of the Aluminium Plant Podgorica while in 1990, under the auspices of the Insti-tute for Geological Research, a drilling in the immediate vicinity of the Aluminium Plant Podgorica was carried out, using equipped exploratory boreholes aimed at deter-mining conditions of pollution and protection of groundwaters south from the Plant (D. Novaković, Z. Popović).

A Study of Determining Environmental Quality in the Zeta Plain (Institute of Tech-nology and Institute for Health Protection, 1992) was undertaken for the purpose of de-

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tecting groundwaters pollution level and it provides an overview of water pollutants in the Zeta Plain, the quality of groundwaters in surveyed section with numerous analyses, dia-grams, maps with contour lines of content of certain elements and pollutant dispersion.

A large number of exploratory boreholes (geomechanical, hydrogeological) and exploitation wells aimed at meeting various needs (water supply, irrigation, energy ef-ficiency etc.) have been drilled in the area of the Zeta Plain in recent years.

This account would not be complete without mentioning complex hydrogeological studies undertaken for the purpose of developing a spring for the Regional water sup-ply system of Montenegrin coast, as well as studies carried out in the area of Tuzi field (Tuško polje) (Radulović M. 1995), Grbavci (Radulović M. et al. 2005; Stevanović et al. 2006) and in the hinterland of the spring Bolje Sestre (Stevanović Z., Radulović M., et al. 2007).

All these studies have provided a set of valuable data when it comes to determining the geological composition, tectonic characteristics, geomorphological and hydrogeo-logical characteristics of the Zeta Plain area.

7.4.6. GEOLOGICAL CHARACTERISTICS7.4.6.1. GEOLOGICAL COMPOSITION

Based on the Guide Book to the Basic Geological Map 1: 100,000, sheet “Titograd” (Živaljević et al. 1962-1967) and “Bar” (Mirković et al. 1962-1968), geological composi-tion of the Zeta Plain and its immediate edge is made of Jurassic, Crateceous, Paleogene and Quartenary depositions (Fig. 58). A detailed and comprehensive description of geo-logical composition of the Zeta Plain has been provided in reference Danilović (2005).

Triassic, Medium Jurassic and Upper Jurassic depositions (J2, J3) are distributed along the Cijevna canyon, in the area from the border with Albania to Dečić, and along the relatively wider area from Karuč to Štitari. They are represented by grey and bright-grey limestone, overlain with dolomite.

Upper Jurassic depositions (J3) make the strip of terrain north from Malo Blato as well as part of the terrain from Dečić to the Cijevna canyon. They are developed in limestone-dolomite facies.

Lower Cretaceous sediments (K1) are developed on both sides of the Cijevna River as well as in the narrow strip from Malo Blato to Štitari. They are represented by thick bedded and bedded limestone, dolomitic limestone and dolomite.

Upper Cretaceous sediments (K2) have the widest distribution in the studied area. They are distributed along the east and the west edge of the Zeta Plain, in the section from the Morača to the Cijevna and from the Sitnica to Malo Blato. They also make the palaeorelief of the Zeta Plain, aggraded by glacifluvial sediments. They are represented by limestone-dolomite facies, i.e. bedded and thick bedded limestone, dolomitic lime-stone and dolomite.

Paleogene deposits (Pg) build a narrow area, northeast from the Zeta Plain, which continues from Morača towards Fundina. They are represented by flych facies, made of breccia, conglomerates, clay and marls, sandstones and sand limestone.

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The exploratory drilling in Donja Zeta (Gostilje) detected clayey sand, gravel and clay. Drilling led to determining the thickness of these sediments which dip below the Quartenary sediments at the depth of 117 m. Based on the geophysical studies, the thickness of these sediments may be inferred to range up to 700 m.

Quaternary deposits (Q) have the widest distribution in this area and they are rep-resented by glaciofluvial (glf), limnoglacial (lgl), deluvial (d), alluvial (al), terrace (t) and aeolian sediments (Fig. 58).

Glacial deposits (moraines) are represented by semi-rounded blocks, gravel and sand, with and without clay and they build the terrains northeast from Podgorica.

Glaciofluvial sediments are represented by sand and gravel. They are mostly of carbonate origin, while grains of magmatic origin may be found, as well as grains of Paleozoic and Medium Triassic conglomerates. These sediments are occasionally close-grained, and occasionally they turn into pebbles with over 10 cm in diameter. Drilling detected overlay of interbeds of different granulation within these spacious glacioflu-vial sediments of the Zeta Plain and occasionally lenses of close-grained sands occur as well. These sediments are loosely or tightly packed forming conglomerates. Radulović V. (1997) states that the these sediments are particularly tightly packed in the north part of the plain, and along the beds of the Morača River and its tributaries the Ribnica and Ci-jevna, but they can also be found by drilling a well, particularly above the groundwater level. Along river beds the sediments are so packed that they do not collapse in vertical side cuts with heights over 10 m.

The very beds of the Morača River and its tributaries are overlain by alluvial gravel and sand deposits.

Close-grained sand, i.e. aeolic sediments may be found on more locations along the Zeta Plain and on the hills from the north side. Such sediments occur in the form of lenses and inside the glaciofluvial sediments.

Carbonate detritus with narrower or wider distribution – deluvial sediments may be found on the slopes of the hills at the edge of the plain.

Significant deposits of laterite clay may be found in karst formations along the edge of the Zeta Plain.

7.4.6.2. TECTONICS

The Zeta-Skadar Lake Valley is one of the biggest tectonic depressions in Dinarides. The lowest parts of the depression are under waters of Skadar Lake. The bed of the lake is below the sea level, i.e. crypto-depression (e.g. sublacustrine spring Raduš spring).

Radulović V. (1997) states that the Zeta-Skadar Lake depression was formed due to the deviation of general strike of Dinaric structures from northwest to southeast. Di-naric structures turned from the known regional strike of the Dinarides, i.e. northwest to southeast, to west-east and southwest-northeast strike in the area of the Zeta-Skadar Lake Valley and in wider region of the southeast Dinnarides, as viewed from the Adri-atic Sea in the southwest to Prokletije and the depression of Metohija in the northeast.

A dip along numerous ruptures occurred in that fracture of the vast stem of the southeast Dinarides which resulted in the Zeta-Skadar Lake depression, from which the

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Fig. 58.. Excerpt from the Basic geological map 1:100000 sheets “Titograd” and “Bar”

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terrains of the Rumija Mountain rose towards southeast and even more vast terrains of the mountain massif Prokletije rose towards east. These regional movements practically caused the vast and powerful carbonate table of the Dinarides to end, as on the territory of Albania these chains end in the immediate southeast of the Skadar Lake. This turn-ing of the Dinaric structures in the west-east direction and further in the southwest-southeast direction is named Metohija strike by Cvijić.

East and west edges of the plain are intersected by numerous faults, some of which are reverse. Generally speaking, those faults dip mostly towards north, just like carbonate sediments beds, while its regional strike is from north to west (Živaljević et al. 1967).

7.4.7. HYDROGEOLOGICAL CHARACTERISTICS OF THE ZETA PLAIN GRANULAR AQUIFER

The granular aquifer distributed on the territory of the Zeta Plain is of significant importance for solving the problem, since it represents a precious water resource, espe-cially in hydrological minimum. This aquifer is partly formed in the alluvial sediments of the Morača River and Cijevna River, and in glaciofluvial sediments (covering the area of 200 km2 and with thickness ranging from 30 to 100 m) which overlay the limestone of paleorelief.

Glaciofluvial sediments are represented by gravel, sand, loosely clayey sandy gravels, loosely packed sandy gravel, loosely and tightly packed conglomerates. At their con-tact with Mesozoic limestone and dolomitic limestone from the floor, laterite clay (terra rossa) occasionally occurs.

Glaciofluvial sediments in the Zeta Plain are characterized by granular porosity. Within the highly permeable rocks represented by gravel, sand, sandy gravel and loose-ly packed conglomerates may be extracted rocks with low permeability represented by tightly packed conglomerates and gravely-sandy sediments with higher distribution of laterite clay.

Alluvial sediments of the Morača River and Cijevna River represented by closely-grained sands on the surface and sandy gravels in the lower beds (below 3 meters) are distributed in the area of the Zeta Plain as well. These sediments are characterized by high value of hydraulic conductivity (Kf > 10-1 cm/s).

The granular aquifer of the Zeta Plain is recharged by the atmospheric waters, by a sinking of Morača River and Cijevna River, and through subterranean discharge of karst aquifer from the limestone terrains at the edge. Aquifer is discharged mostly at the south edge of the plain where a large number of small streams flowing into the lake (the Plavnica, Zetica, Gostiljska River, Svinješ, Pjavnik, Velika and Mala Mrka, etc.). The granular aqufer of the Zeta Plain is characterized by high permeability, with mean value of hydraulic conductivity of about Kf=5.0 x 10-3 m/s, and with transmissibility coefficient T=1.79 x 10-2 m2/s.

The effective infiltration for the granular aquifer of the Zeta Plain (Table 16) is as-sessed by using the following formula:

Ief = P – ET

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where,

Ief – effective infiltration (mm),P – the amount of precipitation (mm),ET – evapotranspiration (mm).

The precipitation data have been collected by means of perennial measurements at the climate station “Podgorica”, and potential evapotranspiration has been assessed by applying the Penman method (Section 8.4.2.4.). During the summer months, when po-tential evapotranspiration exceeds precipitation, atmospheric waters are not infiltrated into the underground at all.

Table 16. The table of mean monthly and annual precipitation (mm), evapotranspiration (mm), effective infiltration (mm and %)

Water balance elements

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

Precipitation (mm) 180 174 146 132 92 62 38 62 115 176 238 221 1636

Evapotrans-piration (mm)

34,5 51,4 84,3 107,8 150,6 183,5 220,9 202,1 130,0 81,7 45,2 31,6 1353

Effective infiltration (mm)

145,5 122,6 61,7 24,2 0 0 0 0 0 94,3 192,8 189,4 830,5

Effective infiltration (%)

80,8 70,5 42,3 18,3 0 0 0 0 0 53,6 81,0 85,7 50,7

8.4.8. GROUNDWATER MATHEMATICAL MODEL OF ZETA PLAIN

The regional groundwater mathematical model for the wider area of the Zeta Plain has been primarily developed to amend the data base for solving numerous water man-agement issues. Particular attention is focused on developing detailed and extensive model of groundwater flow and pollutants transport towards springs “Ćemovsko polje”, “Dinoši” and “Vuksan Lekići”, for which protection zones had to be determined. Results of the mathematical model have been used in assessing the discharge from the Zeta Plain granular aquifer into the lake. An excerpt from the Report on Developing the Ground-water Mathematical Model of the Zeta Plain has been featured in the following lines.

The regional groundwater model in the area of the Zeta Plain has been developed through following steps:

– Collecting and studying the available data;– Developing the Conceptual hydrogeological model;– Selecting an appropriate computer code (software) for developing the mathemat-

ical model;– Additional on-field data collection;

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– Interpreting all data and preparing them to fit appropriate formats to be input into the model;

– Developing the groundwater mathematical model,– Sensitivity analysis and model calibration;– Model verification.

Collecting and Studying the Available Data

A significant number of literature and fund materials as well as the results of numer-ous field and laboratory measurements have been used for the purpose of developing the regional model. Data synthesis and the description of hydrogeological characteristics of the area have been presented in the Section 8.4.7.

The Conceptual Hydrogeological Model of the Zeta Plain region

The conceptual hydrogeological model has been developed on the basis of the in-terpretation of hydrogeological characteristics of this area, which have been a subject of study for many years (Sections 8.4.5. and 8.4.6.) Thus, developing the conceptual hydro-geological model has called for a schematization of the analyzed hydrogeological system.

The geometry of the hydrogeological system has been schematized with two layers. The first layer has been represented by clastic sediments (glaciofluvial, alluvial, terraced and limnoglacial sediments), and by impermeable sediments (Pl) which occur below the granular aquifer in the south part of the plain. The thickness of the first layer varies, as shown in the Paleorelief Map (Fig. 60); however, the average thickness ranges from 30 to 40 meters. The second layer is “crossed” at 200 m below the sea level (Fig. 59).

The first layer has been schematized as an unconfined aquifer, with variable hydrau-lic conductivity. The values determined by pumping tests have been used as initial val-ues of hydraulic conductivity and other parameters. Hydraulic conductivity values rate of 10-3 m/s have been adopted for the area characterized by distribution of glaciofluvial, alluvial and terrace sediments, while hydraulic conductivity values rate of 10-6 m/s have been adopted for the south part of the plain in the Skadar Lake area, where limnoglacial sediments are distributed. The data on hydraulic conductivity of the second layer are scarce, thus conclusions can be drawn on the basis of the existing knowledge which in-dicates that the part where the granular aquifer appears is heterogeneous, whilst almost completely impermeable sediments (Pl) are distributed in the south part of the plain, below the first layer.

The groundwater flow regime is conditioned above all, by the precipitation regime, the water levels of the Morača, the Cijevna, the Sitnica, the Ribnica, the Urelja and other rivers, the water level of Skadar Lake, by the regime of groundwater exploatation, etc.

The boundary conditions of the conceptual hydrogeological model are schematized by external (divides, lake, rivers at the entering sections) and the internal boundaries (rivers accross the area of the model, rivers (“drains”) of the southern edge, abstraction wells, natural springs, etc.). One of the aims of developing the regional model was to avoid “the artificial”, i.e. hydraulic boundaries when making detailed models of the area around the well for which the protection zones are determined.

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Fig. 59. Conceptual hydrogeological model of the the Zeta Plain region (Radulović M.M. et al. 2010); Legend: 1. Granular aquifer, 2. Karst aquifer, 3. Impermeable sediments, 4. Stream, 5. Spring, 6. Groundwater flow direction, 7. Upper layer, 8. Lower layer, 9. Precipitation, 10. Evapotranspiration, 11. Inflow from surface waters, 12. Subterranean Inflow from the karst aquifer to the granular aqui-fer, 13. Subterranean outflow from granular aquifer to the karst aquifer, 14. Outflow from granular aquifer to the lake, 15. Hydraulic conductivity for glaciofluvial sediments, 16. Hydraulic conductiv-

ity for limno-glacial sediments.

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The boundaries of the second layer, i.e. of the karst aquifer are mostly divides (wa-tersheads) of the immediate catchment area of the Zeta Plain determined on the basis of the geomorphological, geological and hydrogeological criteria. However, the boundaries of the model do not represent the complete basin of the Zeta Plain, which would include the complete basins of the Morača, the Cijevna and the Sitnica as well, but only up to the points from which these rivers begin to sinking in such a way that their have influence to the flow pattern of the the Zeta Plain granular aquifer. Therefore, the northest bound-ary for the Morača River is placed in the zone of the Duga Monastery, at which point the Morača starts to sink. Upstream from this point, according to the available findings, the Morača cannot influence the flow pattern of the Zeta Plain granular aquifer, since it has an impermeable bed. Following this principle the entering points are determined for the Cijevna River (begins to sink in the zone of Trgaj) and the Sitnica River (from Komanski Most) as well. The karst aquifer is bordered by Skadar Lake to the south in Hot and Hum bays, as well as by Malo Blato, where the aquifer discharge takes place, while part of the karst aquifer waters have the possibility to continue flowing, below Skadar Lake. Besides the above mentioned external borders of the second layer, there are also internal boundaries represented mainly by the Morača River (on the section from the Duga Monastery up to Smokovac, i.e. entrance to the valley) and the Cijevna (from Trgaj to Dinoše). Moreover, the internal borders are represented by karst springs such as Ribnica springs, Milješ spring and Krvenica spring, among others, as well as by Straganica spring. Therefore, the mentioned karst springs are also the points through a discharge of karst aqiufer may take place in the rainy period of the year.

The outside boundary of the first layer, i.e. the granular aquifer, is mainly a geo-logical border with the karst aquifer from which the granular aquifer is also recharged. Skadar Lake represents the southern boundary of the granular aquifer. The internal boundaries are defined by Morača River, Cijevna River, Sitnica River, Ribnica River and Urelja River, out of which only the Morača River does not dry up during the dry period. Besides the mentioned rivers, the boundary of the first layer follows smaller streams along the southern edge, which are schematized as the “drains” of the granular aquifer. The artificial discharge of the aquifer takes place through many abstraction wells which one should also have in mind when defining the interior boundary conditions.

As for the water balance elements, the atmospheric water infiltration value has been relatively well known (effective infiltration - Ief), which is assessed by subtracting the calculated evapotranspiration (ET) from the quantity of the measured precipitation (P). The data from the climatologic station “Podgorica” are used for defining the atmospher-ic water infiltration for the first layer, and for the second layer the data from the “Ora-hovo” precipitation station. The effective infiltration (recharge rate) for the first layer, i.e. for the granular aquifer, is assessed by calculating evapotranspiration (it amounts to around 50% of water from precipitation), whereas for the second layer the value of 70 % is adopted based on the results obtained in previous research in the neighbouring karst terrains (Radulović M. M. 2009). The artificial discharge of the granular aquifer by ab-straction of the groundwater from drilled wells (Qexp) is also a parameter which can be approximatelly determined on the basis of the data from the records of the biggest users (Watersuppy System Podgorica, the Aluminium Plant Podgorica, Agrokombinat, etc.).

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The other elements of the water balance are mostly obtained in the process of develop-ment and calibration of the mathematical model, and in this case they include: inflow from surface waters (Qdpv), outflow to surface waters (Qopv), discharge into the Lake (Qoj), subterranean recharge from the karst aquifer to the granular aquifer (Qok), subterrane-an discharge from the granular aquifer into the karst aquifer (Qdk), etc.

Selection of the appropriate computer code for developing the mathematical model

The groundwater mathematical (numerical) model is a system with n differential equations of groundwater flow and with as many unknowns. For resolving such a system of equations it is necessary to use an adequate computer program by which equations are solved in a so-called numerical way. In this case, the Finite difference model is opted for, so that the differential equations are replaced by finite differences and solved using nu-merical methods. For the purpose of developing a groundwater mathematical model of the Zeta Plain area, the best known finite difference model (the MODFLOW) developed by the USA Geological Istitute (McDonald and Harbaugh 1988) has been selected. The MODFLOW belongs to a group of so-called “block-centered” models, the reason being that the equation of groundwater flow refers to the center of each block, i.e. cell.

Data procession and preparation of adequate files formats

All the data obtained through studying the documentation and through the field wark needed to be processed and prepared in adequate formats suitable for direct entry into the model, so as to assign in a simple way a special value of the appropriate param-eter to each cell. Therefore, special digital files for each spatially variable parameter were created, as follows:

– topography, i.e. the upper boundary of the first layer, – the bottom of the first layer, i.e. the top of the second layer (Paleorelief map),– recharge from precipitation,– initial groundwater levels, specialy for the first and the second layer,– hydraulic conductivity, effective porosity, specific yield, etc. The data from the documentation have been prepared in digital formats, first within

files containing the coordinates (X, Y) in the first two columns, and the examined pa-rameter (elevation, initial GWL, etc.) in the third column. Files prepared in this way have been used for interpolation by using the “kriging” method, with appropriate sub-jective corrections. The final files to be entered cover the whole area of the layer for which the data have been entered. Fig. 60 shows a visual display of the raster elevation file for the bottom of the first layer.

Development of a groundwater mathematical model

The total modeled area covers the surface of about 593 km2. The Zeta Plain covers an area of around 297 km2. The area of the model has been discretized in a plan view by a grid with calls 200 x 200 m to 400 x 400 m. The total area of both layers has been divided in about 10600 active cells.

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Development of a mathematical model primarily comes down to converting a Con-ceptual hydrogeologic model (Fig. 59) into a numerical model.

After discretization of the area of the model, all the cells that were left outside the selected boundaries of the karst aquifer have been marked as innactive cells (Fig. 61). As mentioned before, the model is divided into two layers. The first (upper) layer is rep-resented by a granular aquifer so that it is defined as the unconfined layer. The second

Fig. 60. Digital elevation model of the bottom of Zeta Plain granular aquifer (Radulović M.M. et al. 2010)

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(lower) layer is represented by a karst aquifer, which is mostly the unconfined aquifer (“Unconfined – T Varies”). In the part where impermeable sediments (Pl) are present below the granular aquifer, innactive cells are defined for the second layer.

Fig. 61. The mathematical model grid with the defined boundary conditions for layer 1 (upper layer) (Radulović M.M. et al. 2010). Legend: 1. Cells defined through the River Package, 2. Cells defined by the General Head Boundary Package (GHB), 3. Cells defined by the Drain Package, 4. Cells defined

by the Well Package, 5. Inactive cells

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Absolute bottom and top elevations of the first and second layer have been defined for each cell, by using files prepared in advance. As the bottom elevation of the model, i.e. of the second layer the elevation of -200 m has been selected.

Fig. 62. The mathematical model grid with the given boundary conditions for the layer 2 (lower lay-er) (Radulović M.M. et al. 2010). Legend: 1. Cells defined through the River Package 2. Cells defined through the General Head Boundary Package (GHB), 3. Cells defined through the Drain Package,

4. Inactive cells.

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As for the time discretization, the model has been marked as transient, and divided into 12 periods (“Stress Periods”), with the duration of each period of about 30 days (“Period Length”), and each period has been divided in 3 time steps (“No. Time Steps”).

Horizontal and vertical hydraulic conductivities have been entered for each cell of the model. For the area of glacio-fluvial and alluvial sediments distribution, the value for the horizontal hydraulic conductivity Kf= 9.3 x 10-3 m/s has been established by cali-bration. The effective porosity values of 0.25 have also been specified.

The model boundary conditions have been specifed so as to simulate as realistically as possible the boundary conditions of the conceptual hydrogeological model. However, given the complexity of the natural conditions in general, there are no software pack-ages which could map the real picture from the terrain entirely.

For simulating the bahaviour of the rivers Morača, Cijevna, Sitnica, Ribnica and Urelja the so called River Package has been used with reference to the perennial mean monthly water levels from the hydrometric stations “Zlatica” and “Podgorica” on the Morača and “Trgaj” on the Cijevna (The Hydrometeorological Institute of the Repub-lic of Montenegro). For simulating Skadar Lake behaviour the so-called General Head Boundary Package, GHB has been used, which determined the perennial mean monthly water levels of the lake measured at the hydrometric station “Plavnica” (The Hydrome-teorological Institute of the Republic of Montenegro). The behaviour of small rivers of the southern edge (the Plavnica, the Zetica, the Gostiljska River, the Mala Mrka, the Velika Mrka, the Raičevića Žalica, etc.), through which the Zeta Plain granular aquifer discharges, has been simulated using the Drain Package. The same package was used for simulation of the karst springs on the investigated area. The abstraction of the ground-waters of the granular aquifer of the Zeta Plain has been simulated by using the Well Package, and only those groups of the wells have been included which can significantly influence the flow pattern in the ratio under consideration. The aquifer recharge from precipitation (effective infiltration) has been simulated by using the Recharge Package and the perennial mean monthly precipitation from the climatologic station “Podgor-ica” have been used (WMMPM 2001) for the area covered by the granular aquifer, and for the area covered by karst aquifer on the terrain surface the same data from the rain-fall gauging station “Orahovo” (WMMPM 2001) have been used.

The Results of the Model

The groundwater levels of the Zeta Plain have been computed using a calibrated and verified regional mathematical model. On the basis of this model, it is possible to per-form different hydraulic analyses of groundwater flow such as: hydraulic analyses for the needs of opening new and extending the existing sources for water supply of settle-ments, hydraulic analyses of impact of the planned facilities on the levels of groundwa-ter of the Zeta Plain, delineating the protection zone of the water sources in the area of the Zeta Plain, as well as for, which is especially important in this particular case, water balance assessment of the granular aquifer discharge into the lake (Qoj) (Section 8.4.8). However, for the purpose of more detailed groundwater hydraulic studies, it is neces-sary to develop more detailed mathematical model specially calibrated for the explored

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localities. Given all the advantages of hydraulic analyses on the basis of the mathemat-ical modelling, one should still bear in mind that this is a model which does not offer a possibility of complete mapping of exceptionally complex natural conditions. There-fore, all future analyses based on this model should be carefully conducted. A flow pat-tern obtained by mathematical modelling for the granular aquifer of the Zeta Plain has been presented in Fig. 63.

7.4.9. INFLOW INTO THE LAKE FROM THE ZETA PLAIN GRANULAR AQUIFER

The Zeta Plain granular aquifer mostly discharges alongside its southern edge where a great number of shorter streams are formed, some of which are: the Plavnica, the Zet-ica, the Gostiljska River, the Svinješ, the Pjavnik, the Velika and Mala Mrka. Discharge measurements of all these streams are very difficult to conduct since run off is diffused and takes place on a wide section.

For the needs of assessing the water discharge to Skadar Lake from the northern coast the results of the previously developed mathematical model of groundwater flow in the area of the Zeta Plain (Radulović M.M. 2010) have been used. On the basis of the mathematical model, developed according to a procedure as described before (Section 8.4.7.), the obtained value of the mean annual water discharge to Skadar Lake from the granular aquifer is 11.62 m3/s. Having in mind the complexity of defining the ground-

Fig. 63. Calculated contours lines of groundwater levels obtained by mathematical modeling of the Zeta Plain granular aquifer (for December).

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water balance, the obtained result should be used with a sense of caution, since in cases like this it is always realistic to expect a certain degree of error.

7.5. ASSESSMENT OF THE GROUNDWATER INFLOW INTO HUM AND HOT BAYS

This Section examines the water inflow to Hum and Hot bays from the part of the terrain which belongs to the territory of Montenegro. The hydrogeological conditions in this area (the eastern edge of the Zeta Plain) are much more complex than the condi-tions in the previously described terrains, thus the obtained value of the subterranean discharge into Hum and Hot bays comes to a level of rough estimate.


Hum and Hot bays are located at the far northeastern edge of Skadar Lake (Fig. 9). The whole Hum Bay belongs to the territory of Montenegro, while Hot Bay is shared between Montenegro and Albania. The road Tuzi – Božaj follows the northeastern coast along Hum and Hot bays.

7.5.2. HYDROGRAPHIC CHARACTERISTICS

The most significant river in the area of the eastern edge of the Zeta Plain is the Cijevna River.

The Cijevna River originates on the territory of Albania, at the altitude of about 325 m.a.s.l. In its upstream part drains the impermeable terrains constituted of shale, marl and sandstone. After 7.7 km it flows in the territory of Montenegro, where it has cut into a canyon, first in limestone and dolomite and then in the fluvio-glacial sediments of the Zeta Plain, after which it discharges into the Morača River, at about 14 m.a.s.l. The length of the Cijevna River flow on the Montenegrin territory amounts to about 32.3 km. The mean annual discharge of the Cijevna River at the hydrometric station “Trgalj”, immediately before entering the Zeta Plain, amounts to about 26 m3/s. The maximum mean mounthly discharge of the Cijevna River at this hydrometric station is registered in May, and amounts to around 43 m3/s, while the minimum mean mounthly discharge, registered in July, amounts to around 5 m3/s. In the driest period of the year the dis-charge on this section may decrease to as low as 1m3/s. The waters of the Cijevna River, in the summer period, dry out completely in the part of the flow through the Zeta Plain. It is known that the Cijevna River recharges a great number of karst springs alongside the plain edge, as well as the granular aquifer of the Zeta Plain.

7.5.3. GEOLOGICAL CHARACTERISTICS

The eastern edge of the Zeta Plain is built up of Mesozoic carbonate rocks. On the basis of the data of the Basic Geological Map 1:100,000 sheet “Titograd”, the carbonate rocks are represented by:

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– limestone, dolomitic limestone and dolomite of the Medium and Upper Jurra-sic (J2,3) i (J3

2,3). These sediments form the core of Dečić massif located north from Hum Bay;

– Lower Cretaceous limestone, dolomite limestone and dolomite which have the widest distribution in the hinterland of Hum and Hot bays, as well as in the Cije-vna canyon zone;

– dolomite, dolomitic limestone and limestone of Albian-Cenomanian (K1,2). These sediments occur on the right side of the Cijevna canyon from Dinoša eastward to the border with Albania;

– dolomite, dolomitic limestone and limestone of Turonian (K22). These sediments

also occur within a narrow zone from the point where the Cijevna leaves the can-yon up to the border with Albania;

– limestone, dolomitic limestone and dolomite of Senonian (K23). These are distrib-

uted north of the Cijevna canyon and they build up the broader Fundina area.The wider area of the investigated terrain belongs to the regional geotectonic zone,

in the literature known as the Visoki Krš, i.e. to a tectonic unit the Stara Crna Gora. In the wider study area, besides the fold structures such as the anticline of Dečić,

east of Tuzi, there are numerous faults, among which the Kuči reverse fault stands out. Along this dislocation Cretaceous limestone overlie Eocene flysch sediments from the northeast. Moreover, numerous shorter faults are registered in this area as well, mostly of a general southwest-northeast strike.

The thickness of the carbonate rock complex along the edge and in the paleo-relief of the Zeta Plain is relatively high, and it is assumed to reach several thousand meters. Those are terrains which belong to the holokarst of the external part of the Southeastern Dinarides, known for a great number of surface and subsurface karst landforms (karren fields, dry valleys, canyons, dolines, uvalas, swallow holes, caves, etc.).

7.5.4. HYDROGEOLOGICAL CHARACTERISTICS

The karst aquifer, characterized by combined fracture and conduit porosity, is com-posed of Mesozoic limestone, dolomite limestone and dolomite. It streches out along the edge of the Zeta Plain (Fig. 64), as well as in its bottom. These rocks are separated by numerous discontinuities, such as: interbed planes and numerous joints and fractures. The discontinuities led to high degree of karstification of these rocks. Therefore, they feature a plethora of various caverns variable in size and spatial distribution.

This leads to a very high porosity of the investigated terrains. The atmospheric waters fall on the very permeable terrains and recharge the spacious and rich in water karst aquifer.

In the area of occurence of the karst aquifer many hydrogeological phenomena oc-cur such as: temporary and permanent karst springs, sublacustrine springs, estavelles, caves with and without water, smaller springs and numerous swallow holes.

Karst Springs

Permanent karst springs are very rare in these terrains. In the wider study area the most significant spring is Ribnica spring, located north from the Cijevna canyon

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(the eastern edge of the Zeta Plain; between Dinoša in the south and Masline in the north). This spring zone emerges within a 5 km long section, at the altitudes from 49 to 65 m.a.s.l. Only the most downstream springs, which emerge from limestone on the right side of the Ribnica bed, are permanent. Several springs discharge on this stretch in the dry period of the year with a minimum yield of about 10 l/s. All the other more upstream springs, along the channel of the temporary stream of the Ribnica flow only after abundant precipitation in the area of Kuči and in the basin of the Cijevna. Dur-ing the hydrological maximum almost all these springs are overflowed by waters of the Ribnica, whose discharge then amounts to over 50 m3/s.

Fig. 64. Excerpt of the Hydrogeological Map of Montenegro 1:200,000 (legend given in the Section 7.2)

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From the aspect of the main aim (assessment of the groundwater discharge into the lake), karst springs and sublacustrine springs that occur along the shore of Hum and Hot bays are very important. Along Hum Bay, heading from the west to the east, a minor spring horizon of unknown yield is first encountered (42°18’48.24”N, 19°21’28.92” E). After that in the nortwestern part of Hum Bay one finds the sublacus-trine spring Ploče (42°19’14.22” N, 19°21’21.72”E), whose yield is also unknown. The biggest spring horizon is represented by the springs and sublacustrine springs of Vitoja (42°19’30.54”N, 19°22’4.44”E), which appear in the northeastern part of Hum Bay. In the dry period of the year, when the water level of the lake significantly decreases, two springs on the surface of the terrain can be noticed in this location (Fig. 65), while under the lake water three more karst sublacustrine springs remain that discharge at the depth of around 5 m. The last known sublacustrine springs in this part of the lake shore is called Funija (42°18’14.60”N, 19°22’21.78”E). It is located at the very headland between Hum and Hot bays. This is a typical sublacustrine springs which discharges at about 300 m distance from the shore, from the depth of around 10 m. In addition to the known locations of the mentioned karst springs and sublacustrine springs, it is realistic to expect that they discharge at other places along Hum and Hot bays as well, which have not be detected so far.

The most significant temporary karst springs in the study area are Mileš springs and Krvenica spring, which emerge at the edge of the plain, south of the Cijevna can-yon. In the rainy time of the year, Mileš springs is a spring horizon on a several hundred meters long section, which generate several m3/s of water, and out of which the Rujela stream is formed. The Krvenica is a periodical karst spring that discharges from the

Fig. 65. Sketch of the sublacustrine spring horizon Vitoja (left) and the sublacustrine spring Funija (right) (Szerszeń 2008)

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eponymous cave situated in limestone in the southwestern edge of Dečići. In the rainy period of the year the discharge of this spring is several m3/s.

Smaller permanent karst springs occur along the fault which extends in a north-east-southwest strike, from Trabojina over Helmica and Skorač, further on towards Vuksanlekići.

Besides a considerable number of temporary karst springs, permanent springs oc-cur here as well, some of which are Gornji and Donji Nabom, and the springs in the Helmica area. The minimum yield of these springs is below 2 l/s.

Estavelles

From the hydrogeological aspect the estavelle horizon of the Cijevna River at the eastern edge of the Zeta plain is very important. It is part of the Cijevna bed from the altitude of 100 m.a.s.l to the altitude of 80 m.a.s.l. from which, during the rainy period of the year groundwaters discharge, while in the dry part of the year the waters of the Cijevna River sink, recharging Ribnica springs, Milješ spring, Krvenica spring, as well as the springs along the edge of Hum Bay (sublacustrine springs of Vitoja). This is the part of the Cijevna River bed from the area of the villages Pikalj and Privt to the point where the Cijevna enters into the Zeta plain.

The estavelle horizon appears also at the northwestern edge of Dečići massif, at the contact point of Mezosoic limestone of Dečići and glaciofluvial sediments of Rogamsko Polje. In the rainy part of the year, waters discharge in quantities of even over 10 m3/s along this horizon, whereas during spring and autumn waters of the most upstream Mileš spring sink. The changes of the level of groundwaters of the karst aquifer of the eastern edge of the Zeta Plain have been monitored through the well in Mileš and by the water level in the Krvenica cave. In these hydrogeological phenomena the vertical oscillations of the groundwaters during the year amount to 5-8 m.

Caves

In the karst hinterland of the eastern part of the Zeta Plain there is great number of caves with and without water. The most significant among them is the already men-tioned Krvenica out of which the groundwater periodically discharge. In certain au-tumn and spring intervals this cave becomes a swallow hole recharging from the Mileš springs water, through the branch of the Urelja River. In the dry period of the year it is a cave filled with water.

Swallow holes

Most waters which flow in this karst terrain usually sink after a short distance. The most important swallow holes zone in the dry period of the year is the already men-tioned estavelle horizon located near the place where the Cijevna River leaves the lime-stone canyon (in the vicinity of Dinoše). The hydrogeological watersheds in this part of the terrain are determined on the basis of the results of tracer test performed over the Cijevna bed swallow holes and in the area of Traboina. It is very important to emphasize that the waters of the Cijevna, upstream of Dinoše, outflow in two directions (table 17):

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1. Towards Skadar Lake, through Mileška vrela, the Krvenica and the Vitoja springs, and

2. Towards the Ribnica springs.

7.5.5. PROBLEM OF DEFINING THE GROUNDWATER INFLOW INTO HOT AND HUM BAYS

Given the very complex hydrogeological conditions in this part of the terrain, which are reflected primarily in the occurence of water bifurcation from the mentioned swal-low holes of the Cijevna River towards the four discharge zones, out of which only one is in Hum Bay (Vitoja springs), it is not possible to precisely determine the inflow of groundwater from this terrains. For the Karuč catchment area and the catchment area of the southwestern edge of Skadar Lake the borders are relatively well determined and it was possible to apply water balance methods. However, this is not the case here. More-over, on the basis of the existing data it is not possible to reliably assess the quantities of the sinking of the Cijevna River (one could determine them by succesive hydrological measurements at the two sections – upstream and downstream from the swallow hole), nor is it possible to determine the percentage of those waters flowing towards Hum Bay.

Having in mind the area of the eastern edge of the Zeta Plain from the Cijevna River to Hum and Hot bays, the quantity of precipitation in that area, the estimated capacity of the swallow hole in the Cijevna riverbed and the number of springs where the water discharges, only a rough assessment of the mean annual inflow of the groundwater into Hum and Hot bays can be obtained. That value is assessed at 2.5 m3/s.

7.6. OVERVIEW OF THE GROUNDWATERS INFLOW INTO SKADAR LAKE

To conclude, five areas have been identified from which the inflow of groundwaters into the lake occures. Every area has separately been analyzed so as to give as complete as possible assessments of the subterranean inflowes. By adding the assessed groundwa-ter inflowes from all the 5 areas, it has been concluded that the total groundwater inflow into the Skadar Lake from the territory of Montenegro amounts to 42.12 m3/s (table 18).

Table 17. Table of the hydraulic conections determined by artificial tracer tests (Radulović V. 1989)

No. Location of tracer

injection

Time of tracer

injection

Location of tracer

appearance

Time of tracer

appearance

Differ-ence in altitude

Dis-tance(m)

Velocity of tracer

(cm\s)

1. Ponor – Dinoša in the Cijevna riverbed 16. 09. 1965. Mileš springs –

Mileš 17. 09. 1965. 33 2775 2.75

2. Ponor – Dinoša in the Cijevna riverbed 16. 09. 1965. Spring from the

Krvenica cave18. 09. 1965. 53 5800 3.07

3. Ponor – Dinoša in the Cijevna riverbed 16. 09. 1965. Sublacustrine

spring Vitoja21. 04. 1965. 80 8500 2.05

4. Ponor – Dinoša in the Cijevna riverbed 06. 11. 1965. Ribnica

springs 13. 11. 1965. 37 5125 0.87

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Table 18. Overview of the groundwater inflows into Skadar Lake from the territory of Montenegro

Areas from which groundwaters inflow into Skadar Lake Inflow (m3/s)Southwestern edge of the lake 9,25Karuč Bay 7,0Malo Blato Bay 11,75North edge of the lake (discharge of the granular aquifer of the Zeta Plain) 11,62

Hum and Hot bays 2,5Total groundwater inflow into Skadar Lake from Montenegrin side 42,12

In addition to the mentioned areas, it is realistic to expect inflow of groundwaters from other locations as well, which have not been detected yet. Only a few more areas have been known so far, but since there were no enough data, the discharge could not be assessed in a satisfactory way. These are the following locations: sublacustrine springs near the island of Vranjina, a short stream of Šegrtnica near Ponari, the sublacustrine springs Njivica and Gušeljevo near Dodoši, sublacustrine springs Ploče and Grab in the lower part of the submerged flow of the Crnojevića River, as well as the sublacustrine springs (Modra springs) that discharge in the section from the Poseljanska River to Virpazar.

From these areas a considerably lower discharge is to be expected (up to 3 m3/s in total). Apart from the groundwater inflow from the territory of Montenegro, when analyzing the total water inflow into the lake, the surface inflow from the territory of Montenegro should also be taken in consideration (Morača River, Crnojevića River, Poseljanska River, Orahovštica River and Crmnička River), the surface and groundwa-ter inflow from the territory of Albania, as well as the overall quantities of precipita-tion which fall directly onto the lake surface.

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[85] Radulović V, 1997: Geogeneza basena Skadarskog jezera, Zbornik radova ‘’Prirodne vri-jednosti i zaštita Skadarskog jezera’’, Naučni skupovi, knjiga 44.

[86] Radulović V, (2005): Projekat detaljnih hidrogeoloških istraživanja voda zbijene izdani u terenu parcele br. 14.297/6 kojoj je vlasnik Dejan T. Suškavčević – Zeta, Fond ‘’Geoservis’’ – a D. O. O. Podgorica.

[87] Radulović V. (2006): Geneza, hidrogeološka svojstva i funkcija fliševa u terenima Crne Gore, Crnogorska akademnija nauka i umjetnosti, Podgorica.

[88] Radusinović S., Protić D., Dević N., Jovanović B. (2011): Corine Land Cover Projekat u Cr-noj Gori – Primjena na slivu Skadarskog jezera. Crnogorska akademija nauka i umjetno-sti, Podgorica

[89] Stepanović B. (1957): Skica hidrogeoloških provincija Jugoslavije. Doktorska disertacija, Rudarsko-geološki fakultet, Univerzitet u beogradu, pp. 106, Beograd.

[90] Stepanović B. (1962): Principi opšte hidrogeologije. Posebno izdanje Zavoda za geološka i geofizička istraživanja. Beograd.

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[91] Stepanović B. (1965): Metode hidrogeoloških istraživanja (skripta). Rudarsko-geološki fa-kultet, Beograd

[92] Stevanović Z., Balatov A., Petrović B. (2007a): Elaborat o izvorištu Bolje Sestre – rezulta-ti dopunskih hidrogeoloških istraživanja izvorišta Bolje sestre (Malo blato, Skadarsko je-zero), podloge za rešavanje problema vodosnabdevanja crnogorskog primorja. Fondovska dokumentacija preduzeća IK Konsalting, Beograd

[93] Stevanović Z, Radulović M, Shammy Puri, Radulović M. M. (2007b): Karstno izvorište „Bolje sestre” – optimalno rešenje regionalnog vodosnabdjevanja Crnogorskog primorja. Srpska akademija nauke i umjetnosti, Zbornik radova Odbora za kras i speleologiju, br. 9, str. 33–64, Beograd

[94] Stevanović Z., Radulović M. (2007c): Elaborat o dopunskim hidrogeološkim istraživanji-ma izvorišta Bolje sestre (Malo blato, Skadarsko jezero) za vodosnadjevanje Crnogorskog primorja za nivo Glavnog projekta, Fondovska dokumentacija preduzeća IK Konsalting, Beograd

[95] Stevanović Z., Milanović S., Radulović M. M., Ignjatović D. (2010): Rezultati terestrič-kih termovizijskih snimanja na Skadarskom jezeru (neštampani materijal), Podgorica – Beograd

[96] Szerszen A. (2008): Karst springs of skadarsko jezero – Expedition report, Grupa Nurków Jaskiniowych, Warsaw.

[97] Tietze E. (1880): Zur geol. d. karsterscheinungen. Jhrb. d. geol. R. A. 1880. XXX.[98] Tietze E. (1884): Geologiche uebersicht von Montenegro. Jahrb. d. geol. R. A. Wien[99] Torbarov K., Radulović V. (1965): Regionalna hidrogeološka istraživanja Crne Gore i

istočne Hercegovine. Fond stručne dokumentacije Zavoda za geološka istraživanja SR Crne Gore, Sarajevo

[100] USGS (2000): Shuttle radar topography mission STRM, U. S Geological Survey[101] Vlahović V. (1975): Kras Nikšićkog polja i njegova hidrogeologija. Društvo za nauku i

umjetnost Crne Gore, Titograd [102] VOCG (2001): Vodoprivredna osnova Crne Gore, Izradio: Institut Jaroslav Černi – Beo-

grad, Vlada Republike Crne Gore, Podgorica.[103] Zogović D. (1964/65): Kritički osvrt na dosadašnje tretiranje hidrološke uloge dolomi-

ta u dinarskom karstu. Vesnik Zavoda za geološka i geofizička istraživanja, knj. 4, 5. Se-rija B, Beograd.

[104] Zogović D, 1978: Ćemovsko polje, hidrogeološka studija, Fond „Energopro jekt”-a, Beograd.

[105] Zogović D. et al. (1992): Završni izvještaj o izvedenim hidrogeološkim istraživanjima izvorišta Karuč, Fondovska dokumentacija, Energoprojekt, Beograd.

[106] Živaljević M., Pajović M., Đokić M., Škuletić D. (1967): Osnovna geološka karta lista Ti-tograd 1:100.000, k. 34–51. Savezni geološki zavod. Beograd.

[107] Živaljević M., Pajović M., Đokić M., Škuletić D. (1973): Tumač za list „Titograd”, k. 34–51, Osnovna geološka karta 1:100.000. Savezni geološki zavod, Beograd.

[108] Živaljević R., Bošković M. (1984): Rezultati hidroloških istražnih radova u slivu Ora-hovštice. Republički Hidrometeorološki Zavod (RHMZ), Titograd.

[109] Živaljević R. (1992): Hidrogeološka analiza kretanja kraških voda na primjeru sliva rije-ke Crnojevića, Doktorska disertacija, Univerzitet „Veljko Vlahović”. Građevinski fakul-tet, Titograd.

STUDY ON CLIMATE AND HYDROLOGICAL FEATURES

OF THE MONTENEGRIN PART OF THE SKADAR LAKE BASIN

I CLIMATE FEATURES IN THE AREA OF THE SKADAR LAKE BASIN

INTRODUCTIONThe area of the Skadar Lake basin is characterized by different climate types. It

ranges from a mildly warm climate without the dry period over the year, on the East and North of the basin, over a moderately warm climate without a pronounced dry period over the year with dry summers and at least four months annually with aver-age temperatures higher than 10oC (northwestern, western, and southwestern part of the basin), to the Mediterranean-Adriatic climate with dominant hot summer period (a moderately warm rainy climate with dry and hot summers and a pronounced summer dry period, with the average temperature of the warmest month of over 22oC) in the lit-toral region and the Zeta-Bjelopavlići Plain.

(According to Koppen’s classification of climate, the area of the Skadar Lake basin is characterized by Csa and Csb climate types).

1. AIR TEMPERATUREThe average air temperature in the most part of the Skadar Lake basin ranges from

14 to 16oC (the area of the Zeta-Bjelopavlići Plain and to the south from the Lake). Tem-perature decreases towards the north and in the mountainous part on the north and east of the basin it ranges between -2 oC and 0 oC, while in the northwest it is about 6-8oC.

The average summer air temperature ranges from 8-10oC in the north to 15oC in the east (up to 8oC in the highest parts), 18-19oC in the northwest, 18-22oC in the south and in the warmest part of the basin – the Zeta-Bjelopavlići Plain it amounts to around 25oC.

The highest air temperatures in Montenegro were measured in this area (Zeta-Bjelopavlići Plain, in August 2007, 44.8oC). High summer temperatures and long dry periods during summer cause huge evaporation from vast water bodies, whereas small-er waterways completely dry up.

In winter (December, January, February), average winter air temperatures range from -8oC to -6oC in the north, which is the coldest, 1-3oC in the highest regions in the northwest, 2-6oC in the Lake area and further southwards, around 6oC in the Zeta-Bjelopavlići Plain, up to 9 oC in the south of the basin.

The average number of days when the air temperature does not exceed 0oC (cold days) in the Zeta-Bjelopavlići Plain (alongside the valleys of the Zeta and the Morača) and

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to the south from the Lake is 0-5 days, towards the north this number increases and in the regions on the left and right side of the river Morača it amounts to 50-70 days, while in the west it is 20-40 days. The warmest month is July, whereas January is the coldest.

Figure 1 shows the spatial distribution of the mean annual air temperatures.

2. THE AMOUNT OF PRECIPITATIONThe average amount of precipitation in the area of Skadar Lake basin ranges from

1600 to 3500lit/m2 per year; 1600-1800lit/m2 in the area of the Zeta Bjelopavlići Plain, 1800lit/m2 in the north and northwest, 1800-2200lit/m2 in the lake area, 2200lit/m2 in the highest areas on the east up to 3500lit/m2 in the southwest.

The amount of precipitation in summer accounts for 8% (in the south-western part of the basin) to 12% of the overall annual precipitation amount, and ranges, on average, from 180lit/m2 in the south and in the area of the Zeta Bjelopavlići Plain, to 220lit/m2 in the rest of the basin, up to 300lit/m2 maximum in the southwestern part of the basin.

Slika.1. prostorna raspodjela prosječne godišnje temperature vazduha. Fig. 1. Spatial distribution of average annual air temperatures

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The average amount of precipitation during the winter period (December, January, February) ranges from 450lit/m2 in the north, 600-800lit/m2 in the Zeta Bjelopavlići Plain, on the east and the northwest of the basin, to around 850lit/m2 in the Skadar Lake area and around 1300lit/m2 in the south-western part of the basin. The amount of winter precipitation accounts for 30–38% of the average annual amount of precipitation. November is the month with the highest precipitation rate (November precipitation ac-counts for between 13% and 16% of the average annual precipitation) in the entire basin, and the lowest precipitation is recorded during summer months (July and August ac-count for 2-3% of the overall annual amount), which is the feature of the Mediterranean precipitation regime.

The spatial distribution of the mean annual amount of precipitation is shown in Figure 2.

Fig. 2. Spatial distribution of the mean annual amount of precipitation

Sl. 2. prostorna raspodjela prosječne godišnje količine padavina.

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The average number of days with precipitation ranges between 110 and 120 days in the area of the Zeta-Bjelopavlići plain and in the south of the basin, around 130 days on the northwest, west and southwest, and 140-160 days on the north and east of the basin. The mean number of days with precipitation ≥10lit/m2 varies from 50-55 days along the river Morača, 60-70 days alongside the Zeta valley and in the south of the basin, up to about 80 days in other parts of the basin.

In the part of the basin with the highest average amount of precipitation, which is the western and south-western part, the average annual number of days with pre-cipitation >50lit/m2 amounts to about 20 days, >100lit/m2 amounts to about 5 days, and >150lit/m2 amounts to about 4 days.

3. THE MAXIMUM HEIGHT OF SNOW COVER Snow cover is formed in the cold period of the year and the mean maximum thick-

ness ranges from 20 to 40cm in the area of the Zeta-Bjelopavlići Plain and the southern part of the basin and 50-70cm to 120cm on the highest summits in the west of the basin.

Fig.3 The spatial distribution of the mean maximum height of snow cover

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Towards the north the mean maximum thickness of the snow cover increases both on ther left and the right side of the Morača, reaching at the highest summits the thickness of 150 to 200cm.

The formation of the snow cover starts in October and lasts until April, whereas in the higher mountainous regions in the north and east it lasts even longer.

The mean annual number of days with snow cover ≥10cm ranges from 5-10 days in the southern basin and in the Zeta-Bjelopavlići Plain, through the Zeta and Morača Val-leys. Towards the north the number of days with snow cover increases and amounts to 120-150 days, which is the same as in the eastern part of the basin. In the northwest the number of days with snow cover ranges from 20-40 days, whereas on the southwest of the region at higher altitudes the number of days with snow cover ranges from 60 to 90 days.

The mean annual number of days with -snow cover ≥30cm in the southern part of the basin and in the Zeta-Bjelopavlići Plain amounts to around one day, and alongside the Zeta Valley around 5 days. Towards the north, alongside the Morača Valley the amount increases from 5 to 20 days, whereas in the higher areas to the west and east from the flow of the Morača it ranges from 70 to100 days, while on the west and south-west of the basin the number of days with snow is 20-40.

The mean annual number of days with the snow cover ≥50cm in the north, along-side the Morača Valley ranges between 1 and 10 days, towards the mountain peaks to the left and right of its flow around 100 days, 5 and 10 days in the western part of the basin, while in the south-western part it amounts to as many as 40 days.

Figure 3 shows the spatial distribution of the mean maximum height of snow cover.

4. CLOUDINESS AND SUNSHINEThe mean annual cloudiness expressed in tenths of (the coverage of) the whole sky

with clouds ranges from 4.5 tenths in the south to 6.5 tenths in the north and the east, that is, from 45% of the sky cloud cover in the south to 65% in the north and east.

The mean annual number of sunshine hours is 1400 in the highest parts in the east, 1600 in the north, 2500 in the area of the Zeta-Bjelopavlići Plain, 2000-2200 in the northwest, and 2000-2400 in the south.

The highest number of sunshine hours is in July when the daytime duration is the longest and the lowest in December.

5. THE WINDIn the area of the Skadar Lake basin wind is conditioned by orography and chan-

nelled along the river streams. Northerly and southerly winds are prevalent. In the east-ern part of the basin it is a northwesterly wind (most frequently at the speed of 1-3m/s, 8% and the speed of 3-5m/s, 6%) and south-westerly wind (most frequently at the of speed of 1-3m/s, 10%. In the western part of the basin the winds have a prevailing north-easterly and south-easterly direction, while in the area of the Zeta-Bjelopavlići Plain the most prevailing are the winds with a northerly direction at the speed of 3-5m/s and 5-10m/s, and with a southerly direction at the of speed 5-10m/s.

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Probability of occurrence of a particular wind direction in a particular speed interval for Podgorica.

direction /

class intervals (m/s)

0.1–0.5 0.5–1.0 1.0–3.0 3.0–5.0 5.0–10.0 >= 10.0 Total

1 N 0.0% 0.4% 4.1% 6.5% 5.3% 0.0% 16.3%2 NNE 0.0% 0.5% 2.6% 0.8% 0.4% 0.0% 4.3%3 NE 0.0% 0.1% 0.4% 0.1% 0.0% 0.0% 0.7%4 ENE 0.0% 0.3% 1.4% 0.1% 0.0% 0.0% 1.8%5 E 0.0% 0.1% 0.4% 0.1% 0.0% 0.0% 0.6%6 ESE 0.0% 0.2% 2.3% 1.0% 0.3% 0.0% 3.8%7 SE 0.0% 0.1% 1.0% 1.4% 0.4% 0.0% 2.9%8 SSE 0.0% 0.1% 3.6% 2.9% 0.3% 0.0% 7.0%9 S 0.0% 0.2% 4.2% 4.2% 0.4% 0.0% 8.9%10 SSW 0.0% 0.3% 3.0% 0.3% 0.0% 0.0% 3.5%11 SW 0.0% 0.1% 1.0% 0.3% 0.0% 0.0% 1.5%12 WSW 0.1% 0.2% 3.7% 0.4% 0.0% 0.0% 4.5%13 W 0.1% 0.1% 1.4% 0.1% 0.0% 0.0% 1.7%14 WNW 0.3% 0.5% 7.0% 1.1% 0.0% 0.0% 8.9%15 NW 0.2% 0.3% 2.9% 1.3% 0.1% 0.0% 4.9%16 NNW 0.4% 1.0% 9.0% 2.8% 0.8% 0.0% 14.0% Subtotal 1.3% 4.4% 47.9% 23.5% 8.1% 0.0% 84.0% Silences 15.0%

Wind Rose for Podgorica for the period 1995-2003

Ruža vjetra Podgoricu

period 1995-2003.

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LEGEND:

N North NNE North-northeastNE North-east

ENE East-northeastE East

ESE East-southeastSE Southeast

SSE South-southeastS South

SSW South-southwestSW Southwest

WSW West-southwestW West

WNW West-northwestNW Northwest

NNW North-northwest

6. CONCLUSION The Skadar lake basin is located in the zone with high rainfall. The intensities of

precipitation are quite high in this area and in a relatively short time, in certain me-teorological situations with a strong cyclonic activity and strong southerly wind flow, heavy rainfall occurs.

II HYDROLOGICAL FEATURES OF THE SKADAR LAKE BASIN

1. PHYSICAL CHARACTERITICS OF THE SKADAR LAKE BASIN

1.1. MAIN FEATURES OF THE CATCHMENTSkadar Lake is located on the territory of Montenegro and Albania and by the sur-

face it covers it is the biggest lake on the Balkan Peninsula. The largest natural body of water in Montenegro is a complex system, which due to its great hydraulic and eco-nomic importance requires special attention, both on the part of Montenegro and on the part of Albania.

The Skadar Lake basin accounts for about 90% of the total basin of the Adriatic Sea in Montenegro.

The biggest inflow to the Skadar Lake comes from the Morača River with its tribu-taries, while the Lake is discharged through the Bojana River.

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For around 18 km the Bojana runs as an Albanian river and at a stretch of about 25 km up to its mouth into the Adriatic Sea, represents a border watercourse between Montenegro and Albania.

The Drim river, which runs on the Albanian side and flows into the Bojana immedi-ately after its outflow from the lake, has a great impact on the Skadar Lake water regime, because at a high water level it slows hidraulically the outflow from the lake, whereas at extremely high floods the water from the Drim flows partially towards the Lake.

1.2. HYDROGRAPHYThe complex geological, lithological and geomorphological relations on the area of

the Skadar Lake, its immediate surroundings and the catchment area influenced very complex hydrogeological, hydrological and hydrographical conditions of the Lake and of the whole basin.

The geological structure of soil and tectonic relations conditioned that most of the waters of the topographic catchment area of Skadar Lake either on the surface or underground, discharge into Skadar Lake. Certain devia-tions of the hydrological ba-sin from the topographic one have been determined, in the area of Golija, and it is pre-sumed that there exist certain deviations also in the border regions of the Katunski Karst.

Nevertheless, in spite of certain findings on the issue, mismatching between topo-graphic and hydrogeological watersheds, which is not char-acteristic of this area only, de-mands serious and thorough hydrogeological research. Groundwaters appear in the fluvio glacial alluvium, but also in numerous channels and fissures in limestone and dolomite, which have their outlets on the lake bottom or on its rim. They develop from Figure 1. The Skadar Lake basin on the territory of Montenegro

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precipitation, from the inflow from the surrounding catchment areas, as well as from the rivers flowing through the plain area.

The level of groundwaters increases when moving from the Lake northwards so that it amounts to 30m in the period of minimum, while in the maximum period it reaches 36m above sea level (Zagorič). In the areas closer to Skadar Lake the ground water levels range from 6-8m.a.s.l in the minimum period to 8-10m.a.s.l in the maximum.

As for the surface courses the Morača contributes most of the discharge into the Lake. The river source is located in the area of Gornja Morača, at an altitude of around 1000 m.a.sl, where it is formed by merging of the Koritski Potok and Javorski Potok.

Until the point where it flows into Skadar Lake, the Morača receives numerous trib-utaries. In the table to follow data are given for those watercourses on which observa-tions and measurements are performed or were performed.

Table 1. Data on the Morača and its tributaries for which measurements exist

No. Watercourse HS Catchment surface (km2)

Specific run-off (l/skm2)

1 Morača

Ljevišta 46.3 ***Požnja 119.5 59.4Pernica 440.9 66,2Zlatica 985.3 60,4

Podgorica 2628 60,1Tributaries

2 Koštanica Djurdjevina 19.3 64,73 Mrtvica Međuriječje 207.7 69,14 Sjevernica Sreteška Gora 68.3 61,3

5 Mala rijeka Nožica Nožica 36.3 39,3Brskutski p Brskut 33.8 18,0

6

ZetaDuklov Most, 342.2 54,4Danilovgrad, 1215.8 64,7

Sastavci *** ***Tributaries of the Zeta

Sušica Gornje Polje 175 30,8

Gračanica Morakovo 68.2 11,3 Glušje 133 15,3

7 Cijevna Trgaj 357 70,58 Ribnica Podgorica 58.3 48,39 Sitnica Komanski Most *** ***

*** No data

Besides the Morača, the following watercourses flow into Skadar Lake from the west, whose balance is controlled by hydrological stations of which the one on the Rijeka Crnojevića is still active.

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Table 2. The data on other rivers of the Skadar Lake basin for which there are measurements

Watercourse HS Catchment surface (km2) Specific run-off1 Rijeka Crnojevića Brodska Njiva 79.3 83,1

2 Orahovštica Opačac Most 53.2 49,6Orahovo 56.6 54,5

The density of the sources in the Skadar Lake basin is highly uneven. Permanent, intermittent and periodical sources appear in the basin. Some karst springs, in the dry period of the year, become aquifers (izdansko okno) or even caves or pits filled with water. Some karst springs in the period of hydrological minimum start “swallowing” water acting as estavelles.

The most significant are permanent karst springs. The most abundant are those in Nikšićko Polje and the Bjelopavlići and the Zeta Plain, Crmničko Polje and in the bed of the Morača with its tributaries.

The most abundant spring in the Skadar Lake basin is Glava Zete (74 m.a.s.l) situ-ated at the very north-west rim of the Bjelopavlići Plain and with it begins the Donja Zeta, the most important tributary of the Morača.

There are numerous underground springs (“vruljas”) along the rim of Skadar Lake among which the most significant are the following:

– Ploče, Vitoja Funija, towards the border with Albania.– Velja Šujica, Mala Šujica, Krakola, Crno, Bilo and Biotsko Oko – along the rim of

Malo Blato – Volač, Karuč, Đurovo and Kaluđerovo Oko, Modra Oka, Raduško Oko, Krnjačko

Oko, Đuravci, Topluha…– Raduško Oko is the deepest one being over 60 m deep.The outflow from the lake is enabled through the Bojana river, where at the HS Fras-

kanjel and HS Reč (until 2003) only water levels measurements are made.

1.3. TOPOGRAPHYThe highest point in the Skadar Lake Basin is in the area of the topographic water-

shed between the Morača and the Tara on Sinjajevina Mountain (Babin Zub at 2277 m above sea level).

On its southern and south-western side the Skadar Lake basin borders on the basin of the Montenegrin Coast. The watershed between these basins begins on the far south-east of the Lake, from the point where the Bojana flows out of the Lake, and stretches towards the west and northwest through Rumija, Sutorman, Sozina and Paštrovići mountains, continuing from the eastern side of Brajići further towards the northwest and north through the southeastern and eastern branches of Lovćen. This is an under-ground watershed and the topographic and the hydrogeological watersheds for the most part do not correspond one to the other. Such a character and position of the watershed is conditioned by the hydrogeological properties of the terrain.

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The watershed continues over Stara Crna Gora to the north over Pusti Lisac Moun-tain, then over Crvena Kita Mountain in which the watershed lies between the basins of Skadar Lake, Montenegrin Coast and the Trebišnjica River.

The watershed between the Skadar Lake basin and that of the Trebišnjica River lies also underground and for the most part is topographically and hydrogeologically incompatible. It begins with Crvena Kita Mountain and stretches towards the north through the karst terrains of Rudine and Banjani, over Vardar Mountain, turning then towards the northeast alongside Njegoš Mountain all the way to of Crni Vrh, where the watershed of the three catchment areas lies (the Skadar Lake, the Trebišnjica river and the Piva River catchment areas).

The watershed between the Skadar Lake basin and the Piva basin begins, as stated, on the massif of Crni Vrh, turning over Golija Mountain to the east through the terrains of Vojnik Mountain and then to the southeast in the direction of Žurim Mountain. From here the watershed turns abruptly in a direction of northeast over Zebalac and Semolje Mountains, then towards the southeast to Veliko Gradište. This watershed, too, lies partially under ground.

Towards the northeast the Lake basin borders on the basin of the Tara River. The watershed begins in the area of Veliko Gradište and continues in a direction of southeast over the mountains Vučje, Crkvine, Ostrovica and Planinica, all the way to the area of Lake Rikavačko. The watershed of this part of the basin lies underground only at the beginning through the limestone massifs of Veliko Gradište and Vučje, while further on it is mostly on the surface (the topographical and hydrogeological watersheds match).

On a short stretch towards the northeast, the terrains of the Skadar Lake basin bor-der on the terrains of the Lim basin. The watershed spreads over Žijova Mountain pass-ing through the territory of Albania across Prokletije Mountain to Mi I Snikut where the watershed lies between the Lake basin on the north and the northwest, the Lim basin on the north and the Drim basin on the east and the southeast.

The watershed of the Skadar Lake basin and the Drim basin is situated on the ter-ritory of Albania.

2. HYDROLOGICAL STATISTICS The analysis of the quality of input data is the precondition for all future activities

related to the water regime in the Skadar Lake basin. In this part of the study standard statistical procedures will be applied on series of observed and calculated data for hy-drological stations at which there are data series long enough for application of math-ematical statistics methods.

For the reason of its importance, this chapter will also provide an analysis of the minimum guaranteed ecological discharge on the Podgorica hydrological station on the Morača, taking into consideration the plan of constructing hydro energy facilities with reservoirs on it, which, inter alia, implies seasonal regulation of discharge.

The data used in these analyses have been collected exclusively by the Institute for hydrometeorology and seismology of Montenegro.

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2.1 COLLECTION AND PROCESSING OF DATA 2.1.1 DATA EVALUATION

It can be stated that the collection of basic hydrological data and the level of hydro-logical findings on Skadar Lake and the rivers belonging to its basin are not in accordance with the complexity and intensity of the problem along the rivers and at the very lake.

In the Montenegrin part of the catchment area of Skadar Lake, the basis of the hy-drographical network consists of the rivers Morača and Zeta.

The hydrological stations on this waterflows are part of the basic network of the Institute for Hydrometeorology and Seismology of Montenegro. Within a network of water level monitoring and discharge measurement performed regularly by the Institute for Hydrometeorology and Seismology of Montenegro these waterways are studied and defined in terms of balance.

The other waterflows of the basin which were hydrologically examined, or are still within the basic network are: Koštanica, Mrtvica, Sjevernica, Mala Rijeka, Rib-nica, Sitnica and Cijevna as tributaries of the Morača, the waterflows of the Sušica and Gračanica as tributaries of the Zeta, and the Crnojevića Rijeka and Orahovštica, which flow directly into Skadar Lake.

As for the very Skadar Lake, it has been covered both in earlier and present monitor-ings by the three gauging stations: Vranjina, Plavnica and Ckla.

The Bojana River is the only river flowing out of Skadar Lake which drains into the Adriatic Sea. The fact that the discharge measurements are not performed on the Montene-grin side, because the river in the longitude of around 25 km follows the borderline with Al-bania, demonstrates the infeasibility of accurate defining of the balance of the Bojana River.

The water levels on the Bojana River were monitored in the past at the two gauging stations – Fraskanjel and Reč, and at present only the Fraskanjel station remains active.

Table 3 provides an overview of all the existing hydrological stations, including those at which measurements and monitoring are not anymore performed in the Ska-dar Lake basin.

The data on water levels and discharges for the stations indicated in the table are processed and recorded in the databases of the Institute for Hydrometeorology and Seis-mology of Montenegro.

In order to provide a better overview of the simultaneous work of the hydrological sta-tions in the Lake and the river Bojana basin, a graphical map has been developed, from which one can easily detect the operation periods of the stations and the existing data for them.

As can be observed from Table 3 and Figure 2 there are ten (10) currently active hy-drological stations in the analyzed catchment area, six of which are on the Morača with its tributaries, one on the Crnojevića River and one on the Bojana, while two of them are on the very lake.

Since the HS Podgorica on the Morača controls the balance of the entire Morača with tributaries, those waters will be analyzed in this study through the balance of this hydrological station. As for the Skadar Lake stations, the HS Plavnica is analyzed, which is the only one with an uninterrupted series of monitoring on the lake, and for the Bo-jana the HS Fraskanjel data are analysed.

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The hydrological stations Podgorica and Plavnica share the identical monitoring period (1948-2012) while the HS Fraskanjel was put in operation in 1960

The map of the basin shows the position of the ten currently existing gauging sta-tions in the basin of Skadar Lake and the Bojana.

Table 3. The overview of the existing hydrological stations in the Skadar Lake basin

No. Station Watercourse Basin Km from conf luence

Basin surface Period

Morača1 Ljevišta Morača Skadar lake 87.5 46.3 1986–19922 Požnja Morača Skadar lake 79 119.5 1990–19923 Pernica Morača Skadar lake 72.4 440.9 1948–20124 Zlatica Morača Skadar lake 15.5 985.3 1983–20125 Podgorica Morača Skadar lake 31.4 2628 1948–2012

Tributaries of Morača6 Đurđevina Koštanica Morača 0.5 18.7 1985–19937 Međuriječje Mrtvica Morača 0.2 207.7 1948–20128 Sreteška Gora Sjevernica Morača 1.1 68.3 1985–19939 Nožica Nožica Morača 2.88 36.3 1984–199610 Brskut Brskutski potok Morača 0.9 33.8 1986–199611 Podgorica Ribnica Morača 1 58.3 1949–200212 Komanski Most Sitnica Morača 9 * 1971–198013 Trgaj Cijevna Morača 20.4 357 1949–198614 Sastavci Zeta Morača 18.7 * 1980–199815 Duklov Most Zeta Morača 12.3 342.2 1955–201216 Danilovgrad Zeta Morača 27 1215.8 1948–200117 Morakovo Gračanica Zeta 20.5 68.2 1964–199418 Glušje Gračanica Zeta 8.5 133 1967–2002

19 Gornje Polje Sušica Zeta 3.1 175 1948–2004,2007–2012

Tributaries of Skadar Lake20 Brodska Njiva Rijeka Crnojevića Skadar lake 3.03 79.3 1987–200321 Opačac Most Orahovštica Skadar lake 3.4 53.2 1991–199522 Orahovo Orahovštica Skadar lake 2.1 56.6 1965–2001

Skadar lake23 Vranjina Skadar lake Skadar lake * * 1965–1995

24 Ckla Skadar lake Skadar lake * * 1950–2002, 2007–2011

25 Plavnica Skadar lake Skadar lake * * 1948–2012 Bojana

26 Reč Bojana Adriatic Sea 10.8 * 1952–200327 Fraskanjel Bojana Adriatic Sea 20 16520 1960–2012

132Pr

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As can be seen from Figure 2. (An overview of the operation of hydrological stations in the Skadar Lake basin), there is a certain incongruity concerning the periods of op-eration of the Skadar Lake hydrological stations.

One period saw a very good coverage with a network of hydrological stations. How-ever, out of 27 hydrological stations, which were initially installed, only about ten are active nowadays.

The number and the dynamics of measuring discharge on the rivers represent a spe-cial problem. The problem has especially been pronounced over the last 15 years, dur-ing which the number of measurements has decreased by many times, thus, there were several succesive years without a single measurement performed. It resulted in non-updated discharge curves and non-updated evidence on actual changes in the river bed.

With regards to the Bojana River, in spite of its key importance, no discharge meas-urements are performed on any of the sections on its about 25km-long, borderline flow

Slika 3. položaj postojećih vodomjernih stanica u slivu Skadarskog jezera i Bojane. Figure 3. Position of the current gauging stations

in the basin of Skadar Lake and the Bojana

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with Albania. Discharge measurements are performed only at the stations Skhodra and Dajchi in Albania, whereas monitoring of the waterlevel on the Montenegrin side is performed at the Fraskanjel station. Consequently, it has been possible so far to analyze only the water level regime on Skadar Lake and the Bojana River.

The approximate discharge values of the Bojana, taken from the available reports, can only be given as a rough estimate. The table of such a balance of Skadar Lake with the inflow and outflow values is shown below.

Table 4. The balance of the water inflow and outflow from the lake

Montenegrin side inflow Q (m3/sec)– Morača – Podgorica 160 – Morača – Botun 170 – Cijevna – Trgaj 25 – Rijeka Crnojev. – Brodska Njiva 6 – Orahovštica – Orahovo 3 – Sitnica – Podgorica 7 – Surface flows with no measurements – estimateassesment 10 – Direct precipitation into the lake 20 Total surface inflow 241

Albanian side inflow– Vraka and Reliska 10 – Inflow from „vruljas“ and underground springs 53 Total water inflow to the Lake 304

Outflow from the Lake– Bojana Skadar outflow from the Lake 304Inflow from the Drim to Bojana– The Drim Bahčelek 311The Bojana with the Drim in total 615

The analysis of the weater level of Skadar Lake is based on a 65 years long moni-toring of water level at the hydrological station Plavnica, from 1948 to 2012. Among the characteristical water levels, as significant for further analysis the following can be distingushed:

Table 5. Characteristic water levels of the lake based on measurements results– Minimum water level 4,54 masl– Mean low flow level 5.11 masl– Mean level of the lake waters 6.42 masl– Mean high-flow level 8.44 masl– Maximum water level in the analyzed period 10.44 masl– Maximum amplitude of water level variation 5.86 masl– Mean amplitude of water level variation 3.33 m

The useful amplitude of the lake between the mean levels of the minimum and maximum waters (18.44-5.11 masl) is 3.33 m, and the maximum amplitude of the al-teration of the lake water within the extreme levels (10.4-4.54 masl) is 5.86m. These data should be compared with the ones of the lake monitoring, registered on the Albanian

135

side, since, according to some data, the difference in levelling between Montenegro and Albania is about 9 cm.

These water levels correspond to certain surface and volume values of the Lake wa-ter. These values have been obtained on the basis of the surface and volume curve giv-en in the 1976 WMMPoM.

The estimated values of the area and volume of the Lake for characteristic water levels are given in Table 6.

Table 6. Values of the area and volume of the lake for characteristic water levels

Z (masl) Surface (m2) Volume (m3)– Mean maximum water level 8.44 514 x 106 3,57 x 109

– Maximum lake level 10.4 548 x 106 4.59 x 109 – Mean level of the lake water 6.42 472 x 106 2,57 x 109

– Mean minimum water level 5.11 421 x 106 2,00 x 109

In the Drim river basin there are six reservoirs, which exert a certain impact on the river water regime. The Fierza reservoir has the greatest impact on the water regime (Vu=2.300 hm3), and it is managed by a floodway.

An interesting comparative analysis of the changes in the low, medium and high water levels of the lake, after the “Fijerza” reservoir in Albania has been put in operation is given in Table 7.

Table 7. Characteristic water levels of the lake after the “Fierza” reservoir has been put in operation

Z(masl)

Period 1948–1980

Period1981–2012

Period 1948–2012

ΔH(m)

Deviation (%)

Low water levels 5,20 5,10 5,109 0.01 0.196%Medium water levels 6,63 6,20 6,42 0.43 6,7%

High water levels 8,68 8.20 8,44 0.48 5.69%

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1000 2000 3000 4000 5000 6000

100 200 300 400 500

V (hm3)

P ( km2 )

Linija povrsine

Linija zapremine

SKADARSKO JEZEROZ (mnm)

Figure 4. Area and volume curves of Skadar Lake

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On the basis of the data presented in the table above, one can conclude the following:– The assumption that after the construction of a series of reservoirs on the Drim,

due to sediment decrease, the Bojana river bed would cut deeper and, therefore, the river’s low water level would decrease, did not prove as correct, that is, the ac-tual state has remained unchanged.

– As for the medium and high water levels of the Lake, they have also remained within the range of earlier values, and the identified differences can be explained as the change in water volumes of the period, since the last 20 years are known to have been generally dry.

– The expectations that significant changes of the regime of the Bojana and the lake would occur, as a consequence of a more adequate water management in the res-ervoirs on the Drim, were not fullfilled, which was proved by the floods on the Skadar Lake in January 2010. The extreme points of flood flows on the Lake and the Bojana exceeded the recorded absolute maximums, whereas the water levels of the Morača were below the absolute maximum water levels , i.e. they were third in the row of the maximums recorded in the whole observation period.

From all the above mentioned it becomes clear that if one wants to solve problems in the Skadar Lake and the Bojana basin, the balance assessment should be replaced with the real (measured) balance. The indicated shortcomings will quite certainly represent the main problem in the future activities related to the design of studies and projects dealing with the water regime of the Skadar Lake basin.

This speaks in favor of the fact that the importance of this body of water as the pri-mary developmental resource of our country and as one of the key ecological factors, has not been completely recognized, which can be succesfully preserved and valorized only if both its components – the quantity and the quality – are properly studied.

2.2 HYDROLOGICAL STATISTICAL METHODS After examining the duration and continuity of the available data from the hydro-

logical stations in the Skadar Lake basin, a statistical analysis will be conducted on se-ries of hydrological data for three stations: HS Podgorica on the Morača, HS Plavnica on the Skadar Lake and the HS Fraskanjel on the Bojana. The reasons why we opted for these three stations are as follows:

– Over 55% of the waters which inflow into Skadar Lake are monitored on the HS Podgorica on the Morača

– HS Plavnica is the only HS on Skadar Lake at which monitoring has been contin-ually performed since the hydrological station was put in operation in 1948 till the present day.

– Although only the water levels on the Bojana are measured on the Montenegrin side they will be analysed both because of its importance in terms of water man-agement and the role the Bojana has in the functioning of the system Skadar Lake – the Drim – the Bojana.

The main features of these three profiles, given in detailed maps and tables, are:

137

Main features of the water gauge stationSkadar Lake HS Plavnica

No. FeaturesGeographic coordinatesLongitude Latitude 42º 16́ 17´́ 19º 11́ 45́ ´

1 Distance from the river confluence (km) -----

2 Catchment area (km2) -----

3 Elevation “0” of water gauge station (masl ) 4,56

4 Station equipment Automatic station5 Period analyzed 1948–2012

Main features of the water gauge stationRiver: Bojana HS Fraskanjel

No. FeaturesGeographic coordinatesLongitude Latitude 41º 58´ 15́ ´ 19º 23´ 17´́

1 Distance from the river confluence (km) 20

2 Catchment area (km2) 16520

3 Elevation “0” of water gauge station (masl ) -0.07


Main features of the water gauge stationRiver: Morača HS Podgorica

No. FeaturesGeographic coordinatesLongitude Latitude

42º 27´ 05́ ´ 19º 15́ 58´́

1 Distance from the river confluence (km) 31,4

2 Catchment area (km2) 2628

3 Elevation “0” of water gauge station (masl ) 24,6


138

2.2.1 TEST OF HOMOGENEITY AND CYCLICALITY OF THE HYDROLOGICAL DATA SERIES

In order to apply the standard statistical methods it is necessary first to verify the spatial homogeneity and the cyclicality of data.

Cyclicality is tested in order to discover the trends of abrupt changes in data series. Methods, such as moving averages and the two way summary curve are used to this end.

For the three selected hydrological stations– HS Podgorica on the Morača– HS Plavnica on Skadar Lake, and– HS Fraskanjel on the BojanaThe diagrams of 5 year moving averages and the trend lines of mean monthly dis-

charge (HS Podgorica), that is, mean monthly waterlevels at the HS Plavnica and the HS Fraskanjel, respectively, have been analyzed.

– HS Podgorica on the Morača

The basic statistics of the series

Table 8. Basic statistical data of the monitored data series

Statistics of the series

Mean annual discharge

Maximum annual discharge

Minimum annual discharge

Ussr (m3/s) 157.7 1259.2 15.86Cv (-) 0.247 0.292 0.302Cs (-) 0.384 0.534 0.870

The variation coefficient, as a nondimensional exponent of dispersion, represents deviation from the mean value of a certain series. In the particular case, we can see that these deviations are not great and, therefore, may be considered as acceptable.

As for the asymmetry coefficient, it serves to determine the degree of symmetry and flattening of the frequency curve.

The values of the asymmetry coefficient which we obtained for the analyzed series demonstrate that for the series of mean annual discharges the asymmetry is medium, while the asymmetry of low and high annual discharge is high. The asymmetry in hy-drology, according to the classification which we have applied, is usually medium and, often, even extremely high.

By analyzing the trend of the mean annual discharge at HS Podgorica we can con-clude that since 1980 it has shown a negative trend. If we analyze those two periods, we can see that the discharge for the period since when the negative trend began has decreased by around 17% on this hydrological station.

From Figure 6 (Five-year moving averages) we can conclude that the moving aver-ages (The diagram shows the point which marks the mean value for the past 5 years) vary within a relatively broad range.

139

Thus, for example, the minimum average occurred in the period 1989-1993 and it amounted to 120.3 m3/s whereas the highest average was registered in the period 1977-1981, and it amounted to 201.0 m3/s.

Maximum annual discharges at the HS Podgorica (Figure 7. Analysis of the trends of maximum annual discharge at the HS Podgorica) show a moderately positive trend which began in 1979.

At first sight, this contradicts the data obtained from the other two hydrological sta-tions which we have analyzed. Before making the final conclusion on whether the maxi-mum discharges have really increased, or they are the consequence of a combination of several factors, ranging from climate, anthropogenic to inevitable errors occurred when balancing the waters with torrential flows, as is the case with ours, analyses that are beyond the scope of this study should be done.

However, one cannot overlook the fact at which many hydrologists point, that even despite the pronounced dry period over the last 20 years, pronounced extremes occur both with the minimum and the maximum, which means that the trend of maximum waters at the HS Podgorica really is as described.

The duration of flood flows at the HS Podgorica is mainly very short, and it is not illogical to have medium waters showing a negative trend, while the trend of maximum waters increases.

By analysing the low waters Figure 8. (An analysis of the trend of minimum annual discharges at HS Podgorica) at the hydrological station Podgorica it has been concluded that minimum annual discharges show a stationary trend, i.e. that there are no stronger tendencies to change.

Srednji godišnji proticaji HS Podgorica (1948 - 2012)

60

80

100

120

140

160

180

200

220

240

260

280

300

1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Q (m

3 /s)

Osmotreni podaciQsr,visLinear (Osmotreni podaci)

Qsr,viš = 157.7 m3/s

Figure 5. Analyses of the trends of mean annual discharge at the HS Podgorica

140

Petogodišnji pokretni prosjeciHS Podgorica

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Q (m

3 /s)

Osmotreni podaci

Petogodišnji pokretni prosjek

Figure 6. Five-year moving averages

Figure 7. An analysis of the trends of maximum annual discharges at the HS Podgorica

Maksimalni godišnji proticaji HS Podgorica (1948-2012)

300

500

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1300

1500

1700

1900

2100

2300

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1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Q (m

3 /s)

Osmotreni podaciSeries3Linear (Osmotreni podaci)

Qmax,viš = 1259 m3/s

141

– HS Plavnica on Skadar Lake

Basic statistics of the series

Table 9. Basic statistical indicators for HS Plavnica

Series statistics Mean annual water levels Maximum annual water levels

Minimum annual water levels

Zsr (masl) 6.423 8.4 5.109Cv (-) 0.058 0.075 0.053Cs (-) 0.059 0.279 0.238

On the basis of the series statistics it can be said that the deviation from the mean value of the series is low. For the series of the mean and minimum annual water levels the asymmetry coefficient is < 0.1, which practically means that the frequency curve is symmetrical. For the maximum annual water levels CS is 0.279, which indicates the mean asymmetry of these data.

The trend of the mean annual water levels (Figure 9.) at the HS Plavnica on Skadar Lake is negative for the period analyzed. Identically as with the HS Podgorica, the neg-ative trend on the Morača has begun since 1980.

The five-year moving averages (The diagram shows the point that marks the mean value for the last 5 years) vary within the range of 0.932 m. The lowest average occurred in the period 1989-1993 and it amounted to 5.971 m.a.s.l, whereas the highest average

Figure 8. An analysis of the trend of minimum annual discharges at HS Podgorica

Minimalni godišnji proticaji HS Podgorica (1948 - 2012)

0

4

8

12

16

20

24

28

32

36

40

1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Q (m

3 /s)

Osmotreni podaciQ min,višLinear (Osmotreni podaci)

Qviš,min = 15.86 m3/s

142

Srednje godišnje kote HS Plavnica (1948-2012)

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5

6

7

8

9

10

1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Z (m

nm)

Osmotreni podaciZsrLinear (Osmotreni podaci)

Zsr = 6.42 mnm

Figure 9. An analysis of the trend of mean annual water levels at the HS Plavnica


Petogodišnji pokretni prosjeciHS Plavnica - Skadarsko jezero

4

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5

5.5

6

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7

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8

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9

1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

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Osmotreni podaci

Petogodišnji pokretni prosjeci

143

Figure 11. Analysis of the trend of maximum annual water levels at the HS Plavnica

Figure 12. An analysis of the trends of the minimum annual water levels at the HS Plavnica

Maksimalne godišnje kote HS Plavnica (1948-2012 )

6

6.5

7

7.5

8

8.5

9

9.5

10

10.5

11

1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Z(m

nm)

Osmotreni podaciZsr,maxLinear (Osmotreni podaci)

Zsr,max = 8.44 mnm

Minimalne godišnje kote HS Plavnica (1948-2012)

4

4.2

4.4

4.6

4.8

5

5.2

5.4

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6

1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Z(m

nm)

Osmotreni podaci

Zsr,minLinear (Osmotreni podaci)

Zsr,min = 5.11 mnm

144

was registered in the period 1968-1972, when it amounted to 6.903 m.a.s.l (Figure 10. Five-year moving averages).

The maximum and the minimum water levels of the Lake at the HS Plavnica (Fig-ures 11. and 12.) show a slightly negative trend.

The analysis of mean, maximum and minimum levels of Skadar Lake has shown that for the whole observation period they had a slightly negative trend for all the three analyzed series of characteristic water levels. This trend is not much pronounced, thus, we may say that there are no significant deviations from the usual periodical alternation of dry and wet periods.

The maximum that occurred in 2010 was due to a combination several factors act-ing simultaneously, from an extremely rainy series to inadequate management of res-ervoirs on the Drim.

– HS Fraskanjel on the Bojana

Basic statistics of the series

Table 10. The basic statistical indicators for the HS Fraskanjel on the Bojana

Series analysis Mean annual water levels Maximum annual water levels

Minimum annual water levels

Zsr (masl) 1.764 4.7 0.4Cv (-) 0.250 0.175 0.296Cs (-) 0.407 -0.431 -0.284

The values of the variation coefficients indicate that there are no significant devia-tions from the mean series values.

For the mean annual water levels the asymmetry is medium. However, the maxi-mum and minimum water levels asymmetry coefficients are negative, meaning that the occurrence of values in the series higher than the mean values is more frequent.

The mean annual water levels (Figure 13.) at the HS Fraskanjel show a negative trend as well. This hydrological station was put in operation in 1960, thus the analysed series belongs to the period 1960-2012. The negative trend began in 1985, which, with regards to the two previously described stations, is a consequence of a different processing period.

As for the five-year moving averages (Figure 14. Five-year moving averages) the low-est average occurred in the period 1989-1993 and it amounted to 1.226 m.a.s.l, whereas the highest average was registered in the period 1976-1980, when it amounted to 2.180 m.a.s.l. Therefore, the variation of the maximum and the minimum five-year average amounts to 0.954 m.

The maximum annual discharges in relation to the mean value show a slightly nega-tive trend as well.

Contrarily to the mean and maximum annual level trends, the minimum annual levels at the HS Fraskanjel show a positive trend. (Figure 16. An analysis of the trend of minimum annual water levels at the HS Fraskanjel)

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These data should be regarded with considerable caution, especially because the Bojana has to be analyzed also on the basis of the discharge, but these are the data we are unfortunatelly not able to provide. The conclusions on the impact of reservoirs

Srednje godišnje koteHS Fraskanjel (1960 - 2012)

0

0.5

1

1.5

2

2.5

3

3.5

1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Z(m

nm)

Osmotreni podaciZsr,godLinear (Osmotreni podaci)

Qsr = 1.764 mnm

Figure 13. An analysis of the trends of the mean annual water levels at the HS Fraskanjel


Petogodišnji pokretni prosjeciHS Fraskanjel (1960-2012)

0

0.5

1

1.5

2

2.5

3

3.5

1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012God

Z(m

nm)

Osmotreni podaci

Petogodišnji pokretni prosjek

146

built on the Albanian side, the cross-section sediment coverage of the profile on which the observations of the water level were performed would, without field and additional analysis, fall within the category of assumptions. Thus, these will not be examined in this study. The incongruences of the trends confirm the complexity of the system and the need for it to be viewed as an integral system.

Maksimalne godišnje kote HS Fraskanjel (1960-2012)

2

2.5

3

3.5

4

4.5

5

5.5

6

6.5

7

1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Z(m

nm)

Osmotreni podaciZsr,maxLinear (Osmotreni podaci)

Qsr,max = 4.71 mnm

Minimalne godišnje kote HS Fraskanjel (1948-2012)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012

God

Z(m

nm)

Osmotreni podaci

Zsr,min

Linear (Osmotreni podaci)

Qsr,min = 0.41mnm

Figure 15. An analysis of trends of maximum annual water levels at the HS Fraskanjel

Figure 16. An analysis of trends of minimum annual waterlevels at the HS Fraskanjel

147

2.2.3 HOMOGENEITY OF THE DATAThe homogeneity of the data is checked in order to determine if there is a significant

variation of statistical parameters of a hydrological series. In this study we applied the Fisher’s F and Student’s t-test for testing sample vari-

ances. For the purpose of doing tests, the series has been divided into two samples. For the HS Podgorica and the HS Plavnica the first series n1 encompasses the period 1948-1979, while the second n2 encompasses the period 1980-2012.

Such a division was chosen having in mind that with 1979 the positive trend of the mean annual discharges ended.

For the HS Fraskanjel n1 = 1960-1979 and n2 = 1980-2012

Theoretical assumptions

– Student’s t-test (n1, n2 < 30 years).It is assumed that the random variable X=Q follows a normal distribution and that

the variances of the two samples are equal (σx1 = σx2 = σx).The criterion for the evaluation of the mean values is statistics:

21

21

XX

XXt

−

−=σ

where 21 XX −σ

21

11*nnx += σ

The variable t has the Student’s division Sn(t) with n=n1+n2-2 degrees of freedom.

The hypothesis is accepted if 2

12

αα−

<< ttt

– Testing dispersion by the Fisher’s F-testThe condition for the application of this test is that the elements of population are

independent, that the two samples are normally distributed and that the parameters of population are unknown.

The null hypothesis is: 21 xx σσ ≅ . The criterion the for equality of the two disper-sions is the statistics

22

21

x

xFσσ

= (21 xx σσ > )

The t-test shows positive results, that is, according to the definition of the t-test a significant change of the water regime has not occurred on the watercourse.

The results of the F-test, which analyze the change of the variance of the data series (deviation of the data from the mean value) show that there are deviations of the data in the two analyzed series.

An Excel calculation for the adopted tests has been provided below

Student’s t - test

– HS PodgoricaThe assumption is that the variable X follows a normal distribution n and that the

variances of the two samples are equal

148

– HS PlavnicaThe assumption is that the variable X follows a normal distribution and that the

variances of the two samples are equal.

For the period 1948-1979n1= 33

Qsr1= 169.1393St.dev1= 39.76264

v= 32


Qsr1= 6.632938St.dev1= 0.319006

v= 32

For the period od 1960-1979n1= 20

Zsr1= 2.01895St.dev1= 0.386513

v= 19


Qsr2= 146.6793St.dev2 = 35.2095

v = 31


Qsr2= 6.218485St.dev2 = 0.314769

v = 31


Zsr2= 1.610242St.dev2 = 0.402546

v = 32

For the entire periodn = 65

Qsr = 157.7365S t.dev = 37.2776

v = 63


Qsr = 6.422523S t.dev = 0.354776

v = 63


Zsr = 1.764472S t.dev = 0.440803

v = 51

σ = 9.248529 m3/st = 2.428489 the obtained value of the t-test

St. dev1–2= 1.275354α = 0.05

Tkr = 1.998

σ = 0.08802 m3/st = 4.708644 the obtained value of the t-test

St. dev1–2= 1.027108α = 0.05

Tkr = 1.998341

The Ho hypothesis is accepted, the samples are homogenic i.e. from the same population


– HS FraskanjelThe assumption is that the variable X follows a normal distribution n and that the

variances of the two samples are equal.

149

Fisher’s F-test– HS PodgoricaF = 1.275 The obtained value of the F-testFkr = 1.810 The critical value of the F-testF=1.275 < 1.810 There are no significant deviations of the variances of the two analyzed series– HS PlavnicaF = 1.0.7 Obtained value of the F-testFkr = 1.810 The critical value of the F-testF=1.07 < 1.810 There are no significant deviations of the variances of the two analyzed series– HS FraskanjelF = 0.922 The obtained value of the F-testFkr = 0.485 The critical value of the F testF=0.922 > 0.485The results of the F-test, which analyze the change of the variance of the data series

(deviation of the data from the mean value) show that there are deviations of the data of the two analyzed series.

3. FLOOD FLOWIn terms of water management, understanding the flood flow is very important for

construction of objects for protection from floods and for dimensioning of hydrotechni-cal objects. This knowledge is especially important also from the point of view of secu-rity and the economy of construction.

Dimensioning of hydrotechnical objects, performed on the basis of computation-ally underestimated flood flow, leads to an increased risk of flooding and collapsing of objects with all the repercussions of it (Prohaska, 2003).

The term maximum annual discharge implies the highest current value of the river flow on a certain section, registered in the course of a calendar year.

The evaluation of maximum discharges of certain return periods is performed by means of a statistical analysis of the observed discharges at hydrological stations.

While analyzing extreme hydrological values two methods are used: the method of the annual extremes and the peak method (POT-series).

The method of the annual extremes is the most widespread in hydrology and we will also apply it in this study. It is founded on a statistical analysis of the highest observed values in every year (one maximum per year) during the monitored period of N years.

σ = 0.124914 m3/st = 3.271971 The obtained value of the t-test

St. dev1–2= 0.921929α = 0.05

Tkr = 2.007584


150

– HS Podgorica

Figure 17 shows a scale of probability of the maximum annual discharges for the HS Podgorica. The values of the quantiles for ther obtained flood flow vacyclues by prob-abilities of occurrence and by different return periods are shown in the table 11.

For evaluating the flood flow the distribution functions Pirson3, logPirason3, Kricki Menkelja and Gumbel have been used.

Basic statistics series are given in Table 8 within the chapter Hydrological statistical methods.

0200400600800

100012001400160018002000220024002600280030003200340036003800

Q(m

3 /s)

Skala vjerovatnoće max godišnjih proticaja Povratni period (godina)

Vjerovatno ća pojave (%)

Vodotok: MoracaHS: Podgorica

99.9 99 95 90 80 50 30 10 5 1 0.1 0.01

10000 10001002010 2

F-je raspodjele:

― Pirson 3 ― Log Pirson 3 ― Kricki Menkelj x Gumbel

Figure 17 The scale of probability of maximum annual discharges, HS Podgorica 1948-2012

Table 11. Values of flood flow on four distribution functions for HS Podgorica

T P3 LP3 KM GUM1.001 417.0 486.5 403.0 538.6

1.010101 562.8 610.8 552.8 634.91.052632 720.7 747.3 716.7 754.51.111111 816.4 831.7 813.4 854.0

1.25 943.7 946.3 944.6 956.92 1223.5 1209.7 1226.1 1198.8

3.333333 1423.3 1408.3 1423.6 1389.610 1748.0 1751.6 1749.8 1739.820 1919.6 1943.9 1916.8 1946.5

100 2269.7 2361.1 2250.1 2414.61000 2707.4 2931.8 2678.9 3077.1

10000 3104.8 3499.8 3054.8 3605.8

151

The characteristic flood flow, for different return periods for the four distribution functions is given in Table 11.

According to the results obtained, the highest values of the quantiles are obtained by Gumbel Distribution.

– HS Plavnica

The scale of probability of the maximum annual water levels at HS Plavnica 1948-2012, is given in Figure 18., while the value of the quantile is shown in Table 12.

Figure 18 The scale of probability of the maximum annual water levels, HS Plavnica 1948-2012

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

Z (m

nm)

Skala vjerovatnoće max godišnjih kota Povratni period (godina)


Skadarsko jezeroHS: Plavnica

99.9 99 95 90 80 50 30 10 5 1 0.1 0.01

10000 10001002010 2

F-je raspodjele:


Table 12. Values of the flood flow on four distribution functions for the HS Plavnica

T P3 LP3 KM GUM1.001 6.732 6.665 6.244 7.200

1.010101 7.099 7.065 6.662 7.3601.052632 7.452 7.440 7.118 7.5701.111111 7.651 7.647 7.405 7.745

1.25 7.90 7.906 7.726 7.9222 8.414 8.422 8.419 8.340

3.333333 8.754 8.760 8.866 8.66910 9.275 9.269 9.542 9.27320 9.537 9.523 9.879 9.630

100 10.052 10.017 10.555 10.4371000 10.664 10.599 11.610 11.581

10000 11.197 11.102 12.580 12.720

152

The values of the quantiles obtained by all the distributions up to 100 year-maxi-mum water levels are almost identical. For long return periods, or small probabilities of 0.1 and 0.01% the logP3 function yields the lowest results, which is not characteristic of it.

– HS Fraskanjel

The probability scale of the maximum annual water levels at the HS Fraskanjel 1960-2012 is given in Figure 19, and the value of the quantiles in Table 13.

00.5

11.5

22.5

33.5

44.5

55.5

66.5

77.5

88.5

99.510

Z(m

nm)

Skala vjerovatnoće max godišnjih kota Povratni period (godina)


Vodotok: BojanaHS: Fraskanjel

99.9 99 95 90 80 50 30 10 5 1 0.1 0.01

10000 10001002010 2

F-je raspodjele:


Figure 19. Probability scale of the maximum annual water levels, the HS Fraskanjel 1960-2012

Table 13. Flood flow values on four distribution functions for the HS Fraskanjel

T P3 LP3 KM GUM1.001 2.570 2.048 2.430 3.100

1.010101 3.010 2.669 2.923 3.3101.052632 3.445 3.273 3.403 3.6001.111111 3.693 3.605 3.674 3.806

1.25 4.009 4.010 4.009 4.0362 4.665 4.763 4.686 4.578

3.333333 5.108 5.198 5.125 5.00510 5.794 5.757 5.784 5.78820 6.144 5.990 6.113 6.250

100 6.838 6.359 6.725 7.2981000 7.672 6.668 7.454 8.780

10000 8.407 6.847 8.019 9.820

153

For the series of the maximum annual water levels at the HS Fraskanjel, with the negative asymmetry coefficient, the results obtained by logP3 distribution function show a very small difference between the 100-year, 1000-year and 10000 year values.

The maximum value of the quantiles is obtained by Gumbel Distribution. For certain specific purposes (design), before determining the calculation values of

flood flow, the existing series of data have to be separately analysed, that is, the input data have to be tested (parametric and nonparametric tests), detection of exceptions in a series performed and other distribution functions introduced, which would perhaps give more acceptable results and, thus, facilitate the choice of the relevant flood flow.

4. ANALYSIS OF LOW FLOWKnowing the regime and the features of the low flow of a watercourse is very impor-

tant in all branches of water management: supplying of the settlements and the industry with water, discharge of waste-water, irrigation, hydroenergetics... The low flow is also important in river beds regulation, design, building and using of various water manage-ment objects and systems. Understanding law flow is necessary in order to provide water for users downstream from the place in which the water is used for various purposes and to enable convenient conditions for the survival of the flora and fauna in the waterflows.

It is necessary to determine these quantities by hydrological analyses of the water-flow regime in critical dry periods.

– HS PodgoricaThe probability scale of the minimum annual discharge at HS Podgorica 1948-2012,

is given in Figure 20, while the value of the quantiles is given in Table 14.

Figure 20. Minimum annual discharges probability scale, HS Podgorica 1948-2012

0

3

6

9

12

15

18

21

24

27

30

33

36

39

42

45

48

Skala vjerovatnoće min godišnjih proticaja

99.9

Povratni period (godina)

Vjerovatnoća pojave (%)

Vodotok:Mora čaHS:Podgorica

10

99 95 90 80 50 30 10 5 1 0.1 0.01

1000 20100 2 5

F-je raspodjele: ― Pirson 3 ― Log Pirson 3 ― Kricki Menkelj X Gumbel

154

The values of the quantiles for logP3 and the Gumbel Distribution are practically the same; moreover, the results in the compatibility tests are similar. At the same time, they give the maximum values of the quantiles.

– HS Plavnica

The minimum annual discharges probability scale at HS Plavnica 1948-2012 is giv-en in Figure 21, while the value of the quantiles is given in Table 15.

Table 14. Values of the quantiles of low flow on the four distribution functions for the HS Podgorica

T P3 LP3 KM GUM1.001 6.584 6.459 5.894 6.476

1.010101 7.796 7.888 7.537 7.7301.052632 9.322 9.481 9.242 9.2891.111111 10.334 10.481 10.339 10.584

1.25 11.762 11.857 11.823 11.9242 15.174 15.109 15.220 15.074

3.333333 17.789 17.645 17.810 17.55910 22.277 22.206 22.250 22.11920 24.744 24.856 24.656 24.811

100 29.944 30.842 30.110 30.9071000 36.692 39.547 37.194 39.535

10000 42.999 48.791 44.602 48.811

3

3.5

4

4.5

5

5.5

6

6.5

7

7.5

8

Skala vjerovatnoće min godišnjih kota

99.9

Povratni period (godina)


Skadarsko jezeroHS:Plavnica

10

99 95 90 80 50 30 10 5 1 0.1 0.01

1000 20100 2 5


Figure 21 Minimum annual discharges probability scale, HS Plavnica 1948-2012

155

Table 15. Value of the quantiles of the low flow on the four distribution functions for the HS Plavnica

T P3 LP3 KM GUM1.001 4.357 4.380 3.770 4.577

1.010101 4.523 4.537 4.019 4.6801.052632 4.680 4.687 4.312 4.7361.111111 4.768 4.771 4.485 4.810

1.25 4.877 4.877 4.666 4.8862 5.098 5.095 5.082 5.064

3.333333 5.243 5.240 5.364 5.20510 5.463 5.465 5.773 5.46420 5.573 5.579 5.977 5.616

100 5.787 5.806 6.420 5.9621000 6.039 6.080 7.084 6.451

10000 6.256 6.323 7.731 7.060

Taking into account the low asymmetry and the absence of exceptions in the series, the distributions P3 and logP3 give practically the same results. The maximum values of the quantiles are obtained by Gumbel Distribution, whereas the Kricki-Menkel Dis-tribution must be discarded since there is no congruence between the theoretical and the empirical distribution functions.

– HS Fraskanjel

The minimum annual water levels at HS Fraskanjel 1960-2012 are given in Figure 22, and the value of the quantiles in Table 16.

Figure 22. The minimum annual water levels probability scale, HS Fraskanjel 1960-2012

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

Skala vjerovatnoće min godišnjih kota

99.9

Povratni period


Vodotok: BojanaHS:Fraskanjel 10

99 95 90 80 50 30 10 5 1 0.1 0.01

1000 20100 2 5


156

Table 16. Values of the quantiles of the low flow on the four distribution functions for the HS Fraskanjel

T P3 LP3 KM GUM1.001 0.134 0.036 0.105 0.173

1.010101 0.182 0.093 0.161 0.2051.052632 0.234 0.178 0.222 0.2451.111111 0.265 0.235 0.259 0.278

1.25 0.307 0.310 0.306 0.3122 0.400 0.440 0.406 0.392

3.333333 0.466 0.498 0.473 0.45510 0.573 0.541 0.574 0.57120 0.630 0.550 0.623 0.639

100 0.746 0.556 0.720 0.7941000 0.892 0.557 0.829 1.013

10000 1.024 0.558 0.923 1.195

Because of negative asymmetry coefficients and the most probable existence of the exceptions in the series, the function logP3 gives practically the same results for T= 10, 20, 100, 1000 and 10000 years, which is unacceptable. As already mentioned, for some specific purposes (design), before determining the relevant low flow, the existing series of data have to be separately analysed, that is, the input data tested (parametric and nonparametric tests),the existence of the exceptions in the series determined, and other distribution functions introduced in the analysis, adjusted to the analysis of low flow.

5. DETERMINATION OF THE GUARANTEED ECOLOGICAL DISCHARGE

The guaranteed ecological discharge has been determined for the hydrological sta-tion Podgorica on the Morača, because of its future hydroenergetic use and the impact on the system of Skadar Lake and its flora and fauna.

The Law on the Waters of Montenegro (“Official Gazette of Montenegro”, no. 22/08 of April 2, 2008) is not decisive in terms of calculation and the correct selection of the guaranteed ecological discharge, but leaves a fairly wide range of possibilities to the ones processing the data regarding its computation.

In the practice hitherto followed the value of 0.1%Qsr, or 0.15%Qsr for the guaranteed discharge has most often been adopted so far regardless of the period of the year. The reason for the frequent application of this way of computation is reflected in its simplic-ity and in the fact that in such a way lower values of discharge are obtained, which has to be provided to downstream users.

For the purpose of this study, the processors have decided to use the new GEP method for determining the guaranteed ecological discharge (Guaranteed Ecological Discharge), which was developed by Prof. B. Đorđević and T. Dašić.

The GEP method is based on the application of the three parameters:– Mean perennial discharge at the dam, i.e. at the place of water abstraction Q

157

– Low monthly water of the 95% probability, mjesQmin%95

– Low monthly water of the 80% probability,

The following values are adopted for the guaranteed ecological discharge Qekol. gar:

1. In the cold part of the year, which encompasses the period [October - March]

the guaranteed ecological discharge garekolQ . should be chosen so as to fit the quanti-

ty of the monthly low flow of the probability of 95% ( mjesQ

min%95 ), i.e. 30-day low flow of

the same probability (30.min

%95Q ), but such value must neither be lower than 0.1 x Q , nor

higher than 0.15 x Q .

So, in the cold part of the year garekolQ . is chosen on the basis of the relation:

garekolQ . =

×≥×<×≤

<××

×

QQQ

QQQ

iliiliili

QQQ

Qzazaza

QQ

iliQ

Qmjes

mjes

mjes

mjes

15.015.01.0

1.015.0

1.0

30.min%95

30.min%95

30.min%95

.min%95

.min%95

.min%95

30min%95

.min%95

2. In the warm part of the year, which encompasses the period [April - September] the guaranteed ecological discharge garekolQ . should be selected so as to fit the quanti-ty of the monthly low flow of the probability 80% (

mjesQmin

%80 ), i.e. 30-day low flow of the same probability ( ), but such value must neither be lower than 0.15 x Q , nor higher than 0.25 x Q . So, in the warm part of the year garekolQ . is chosen on the basis of the relation:

garekolQ . =

×≥×<×≤

<××

×

QQQ

QQQ

iliiliili

QQQ

Qzazaza

QQ

iliQ

Qmjes

mjes

mjes

mjes

15.015.01.0

1.015.0

1.0

30.min%80

30.min%80

30.min%80

.min%80

.min%80

.min%80

30min%80

.min%80

In case the values of the guaranteed ecological discharges with the defined prob-abilities of the low flow exceed the ranges defined by the above rules and inequations – the yield values are adopted.

– Probabilities of the minimum monthly discharges, HS Podgorica on the MoračaFor determining the guaranteed minimum in our case, the distribution of prob-

abilities of the minimum monthly discharges Table 17 was first determined and the graph of probabilities of minimum monthly discharges developed Figure 23.

158

Table 17. Distribution of the probabilities of the minimum monthly dischargesM

onth P

(%)

1% 5% 10% 30% 50% 80% 90% 95% 99%

I 217 165 140 98.4 75 46.7 36 29 19.6II 190 148 129 94.1 73.9 47.9 37.2 29.8 18.8III 220 171 148 107 83.6 53.5 41.2 32.7 20.3IV 284 225 197 146 116 79 63.4 52.5 36.4V 254 199 172 125 98.9 64.1 49.9 39.9 25.2VI 121 92.4 79.2 56.4 44.1 29.6 24.3 20.9 16.5VII 52.9 41.8 36.7 28 23.3 17.7 15.7 14.4 12.8VIII 31.8 26.5 24 19.4 16.6 13 11.5 10.4 8.74IX 66.3 44.2 35 21.6 16.1 12.3 11.7 11.5 11.5X 186 106 75 33.2 19.9 14 13.6 13.6 13.6XI 236 161 129 75.5 49.4 23.1 15.5 11.6 7.92XII 321 215 170 101 70 43.3 37.3 34.9 33.3

Finally, the guaranteed discharge for the HS Podgorica on the Morača

Period [October – March]

= 11.6 m3/s

0.1 x Q = 15.8 m3/s

0.15 x Q = 23.6 m3/s

Since mjes

Qmin%95 < 0.1 x Q then, for the period [October - March] the GEP should be

adopted so as to equal 15.8 m3/s, that is, For the period [October – March] Qekol gar = 15.8 m3/s

Period [April – September]mjes

Q.min%80 = 12.3 m3/s

0.15 x Q = 23.6 m3/s ⇒0.25 x Q = 39.4 m3/s

Since mjes

Q.min%80 < 0.15 x Q then for the period [April - September] the GEP should

be adopted so as it is not lower than 23.6 m3/s nor higher than 39.4 m3/s, that is,Period [April - September] Qekol gar = 23.6 m3/s

159

REFERENCES[1] Branko Radojičić, Vode Crne Gore[2] M. Bošković, M. Popović, N. Alilović: Prilog o geogenezi Skadarskog jezera, njegovim pri-

hodnim i rashodnim komponentama i istorijatu aktivnosti na njegovoj regulaciji.[3] B. Đorđević, M. Šaranović: Hidroenergetski potencijal Crne Gore[4] B. Đorđević, G. Sekulić, M. Radulović. M. Šaranović: Vodni potencijali Crne Gore [5] Zavod za hidrometeorologiju seizmologiju Crne Gore: Arhivska dokumentacija Hidrološ-

kog sektora

5%

10%

30%

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

I II III IV V VI VII VIII IX X XI XII

Mjeseci

Qsr

(m3 /s

)

50%

90%

99%

1%

OBEZBIJEĐENOST MINIMALNIH MJESEČNIH PROTICAJA

Morača HS Podgorica period: 1948-2012

95%

80%

Figure 23. Probabilities of the minimum monthly discharges HS Podgorica 1948-2012


DEVELOPMENT OF HYDROLOGICAL AND HYDRAULIC STUDY OF

REGULATION OF SKADAR LAKE AND BOJANA RIVER WATER REGIME

IPA PROJECT

Volume I

PrepressBojаn R. Popović

Medeon d. o. o. – Podgoricа

Copies200

Printed byMedeon d. o. o. – Podgorica

2014.

CIP – Каталогизација у публикацијиНационална библиотека Црне Горе, Цетиње

ISBN 978-86-7215-347-7 (Vol. 1)COBISS.CG-ID 25880848

Development of Hydrological and Hydraulic Study of Regulation of Skadar Lake and Bojana River Water...

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