PRIORITIZATION OF MICRO- WATERSHEDS -...
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7.1 INTRODUCTION
Optimal management of natural resources on sustainable basis is of utmost
importance in today’s context. Sustainable increase in production of food grains,
fiber, fodder, etc. is a most to meet the need of increasing population. The
planners face a problem of striking a balance between two competing demands of
development and conservation of natural resources. Therefore, management needs
to address different dimensions related to physical condition of resource,
environmental aspects, economic viability, social acceptability etc. If plans are to
incorporate all parameters discussed above, a holistic approach needs to be
adopted. To generate integrated plans for an area development/management, one
requires information on individual elements as well as the inter-relationships
among different elements of the terrain. This could be achieved if the thematic
maps on land use/ land cover, soil, slope, water resources etc. are seen in an
integrated fashion. One of the difficulties faced by planners relates to the
availability of information on different resources and their accuracies, recentness
of the data, compatibility of different data sets in terms of information details,
scale, format etc, temporal changes with respect to utilization, degradation etc. in
a spatial context. In addition, planners also require a reliable mechanism to assess
the success of the implementation of various schemes. Inputs from science and
technology play a vital role in providing necessary data and in analyzing these
data sets to arrive at optimum solutions.
The growing pressures on land for food, fiber and fodder in addition to industrial
expansion and consequent need for infrastructure facilities due to even increasing
population have given rise to competing and conflicting demands on finite land
and water resources. About 175 Mha of land in India, Constituting about 53 per
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cent of her total geographical area, suffer from deleterious effect of soil erosion
and other forms of land degradation. A country like India that supports 16 per cent
of world population on 2 per cent of the global land area, the problem is serious
enough. Keeping in view of the ever increasing population and need for food
security for the future generation, it is realized that the water and land resources
need to be developed, used and managed in an integrated and comprehensive
manner. It has already been realized that the soil and water conservation measures
carried out on a watershed basin play a prominent role in this strategy of
comprehensive land and water management.
A watershed is an area from which runoff resulting from precipitation flows past a
single point into large stream, river, lake or ocean. Thus, a watershed is the
surface area drained by a part or the totality of one or several given water courses
and can be taken as a basic erosional landscape element where land and water
resources interact in a perceptible manner. Watershed management is the process
of formulation and carrying out a course of action involving modification of the
natural system of watershed to achieve specified objectives. It implies the proper
use of land and water resources of a watershed for optimum production with
minimum hazard to natural resources. Remote Sensing and GIS techniques have
emerged as powerful tools for watershed management programmers.
A watershed is a natural and complete topographical and hydrological entity that
collects and converge all the rainwater falling on it to a common outlet. Therefore
a watershed is an ideal unit for management and sustainable development of its
resources. The basic natural resources of watershed include water, land and
vegetation.
Rapid increase in population, urbanization, expansive and intensive agriculture,
large construction, etc., have resulted in ever increasing demands on land and
water, and caused enormous degradation of environment and forest, loss of
productive soils, depletion and pollution of surface and sub-surface water
resources, and sedimentation of rivers and reservoirs. Therefore the existing
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condition for conservation and improvement of soil is surface and subsurface
water resources and most importantly the forest resources.
Vegetation cover is the most important and most of the environmental degradation
and its harmful effects faced today are mainly due to the degradation of vegetation
cover. Afforestation that is improvement of the vegetative cover naturally
improves the soil conditions, helps in its effective conservation, leads to
improvement in surface and subsurface water resources reducing the adverse
effects such as draught, improving agriculture, and in turn improving the
vegetation and environmental conditions. Topography, the surface configuration
of the terrain is another important attribute in the hydrological processes in a
watershed. Slope of terrain is one attribute of topography that can have very
adverse effect on both soil and water resources as well as on land use development
in a watershed.
The effects of slope, land use that is mainly vegetation cover and soil properties
on the hydrological processes especially soil erosion of a watershed are well
summarized in the literature. As can be seen, amongst the three attributes, viz.
topography, land use and soils topography has the greatest influence. As the slope
steepness increases, runoff velocity and volume increases, with it the kinetic
energy and carrying capacity of the surface flow increase, infiltration decreases,
soil slope stability decreases and the soil displacement down the slope increases.
Vegetation cover protects the soil against the impact and energy of the falling
raindrops and dissipates it. It reduces the velocity, kinetic energy and the volumes
of runoff and increases the infiltration capacities of the soils, thus reducing the soil
erosion. This consequently improves the physical, chemical and biological
properties of the soil.
The deterioration of natural resources is as old as the first man who cut the first
tree to practice arable farming. In India’s post-independence period, the increase
in agriculture using excessive irrigation, over-application of fertilizers and
bringing more area under cultivation has led to serious erosion hazards, water
logging, changing water courses, soil erosion, and deforestation in large areas, soil
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salinity and alkalinity. To compound the problems further, recurrent natural
disasters like drought and floods put constraint to natural resources development.
The population explosion coupled with urbanization, industrialization and the
resultant decrease in arable land available for agriculture have put tremendous
pressure on the land and water resources. In India, 75% of the total cropped area is
un-irrigated and it accounts for 42% of the total crop production. The rainfall in
these areas exhibits wide variations in time and space, introducing an element of
risk, uncertainty and instability in crop production. This is primarily due to the
monsoon nature of rainfall and its inadequacy to meet the demands, in the semi-
arid tropics; the rains are of high intensity and, together with lack of organic
matter like the black soils of India. This results in excess runoff, poor moisture
intake and loss of precious topsoil due to water erosion. This is, further aggravated
by high prevailing temperatures leading to greater evaporation losses. Hence,
accurate and timely mapping, monitoring and assessment of conditions in the
watershed area are essential for assessing land and water resources and their
optimum utilization for sustainable development.
In dry land agricultural areas productivity is lower due to inadequate moisture
availability at crucial stages of crop growth. Soil and water conservation measures
have been long practiced to protect the productive lands. These measures are
suggested based on terrain characteristics like land use, soils slope, hydro-
geomorphology, etc. Remote Sensing and GIS techniques have been used recently
to arrive at cost-effective plans for conservation and development measures for
watersheds.
Several scientist have worked using Remote Sensing, GIS Techniques and
different erosion estimation models, prioritize the watersheds and to find
appropriate location for check dam construction in different areas of entire
watershed. Prioritization of watersheds using remote sensing data by sediment
yield prediction has been carried out by Chakraborti (1991). Site location for
check dam construction by studying runoff in part of Mahi River has been carried
out by Durbude et al. (2001). GIS overlaying techniques has been used to locate
the potential zones of ground water (Murthy, 2000). Chinnamani (1991)
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estimated sediment yield using remote sensing data. Mani et al (2003) carried out
soil erosion studies of part of the world’s largest river island, Majuli River- Island,
using remote Sensing data and ILWIS software.
7.2 REVIEW OF LITERATURE
R.E. Horton and A. E. Strahler (1940s and 1950s) - First initiated
Morphometric studies in the field of hydrology in the 1940s and 1950s.
Determining geomorphic parameters in the past has been a tedious and time
consuming process due to the efforts needed in delineation of watersheds and
calculating the respective watershed areas.
Nautiyal (1994) - Research provides morphometric analysis by focusing on the
analysis of the drainage basin using aerial photographs. Paper evaluates the real
life case study of Khairkuli basin, District Dehradun, India using morphometric
analysis using aerial photographs.
Sujata Biswas, S.Sudhakar and V.R.Desai (1999) have reported on
“Prioritization of Sub watersheds based on Morphometric Analysis of Drainage
Basin; A Remote Sensing and GIS Approach.” They aimed for prioritization of
sub watersheds enveloping the Nayagam Block, Midnapore District, West Bengal
for soil erosion purpose. They divided the study area in 9 sub watershed. They
used Remote sensing data like FCC of IRS-1C LISS III satellite data, SOI
Toposheeet of 1:50,000 scale and GIS for morphometric analysis. They prioritized
all the sub watersheds and provided a ranking to each sub watershed. All the sub
watersheds were prioritized and ranking to each sub watershed was given based
on soil erosion.
Khan (2001) considered an integral part of the Guhiya basin with a total area of
1614 km2 for his study. Considered an integral part of the Guhiya basin with a
total area of 1614 km2 for his study. The basin contains numerous rivers (the
Guhiya, the Radiya, the Modiya, the Guriya and the Lilri), which finally drain into
Sardar Samand reservoir, located to the southeast of the Jodhpur district of
western Rajasthan, India. Morphologically, geo-morphologically and hydro
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logically the basin had good variations. The priority watershed concept study was
made involving (1) appraisal of natural resources such as landform, storage,
drainage morphometric, and present land-use/ land-cover using topographical
sheets at 1:50,000 scale, satellite data at 1:250,000 and 1:50,000 scale and field
survey and their thematic mapping; (2) delineation of watersheds using same data
source; (3) mapping and assessment of erosion intensity units (EIU) using
Geographical Information System (GIS) procedures, and (4) estimation of
sediment yield index (SYI).
Gopalkrishna (2004) investigated the Hemavathi and Yagachi tributaries to river
Cauvery, India. The drainage system was dendritic to sub-dendritic and the
geomorphology of the area controls the geometric configuration of the aquifer
media. Major structural features observed in the area were Hemavathi-Thirthahalli
mega lineament. The other lineaments were parallel to mega lineament and these
controlled the streams and their flow directions. Hemavathi and Yagachi were
found to be perennial; whereas the remaining streams are seasonal.
Gwod (2004) carried out morphometric analysis and their relative parameters
were quantified for the Peddavanka basin, Anantapur district, Andhra Pradesh,
India. The quantitative analysis of the morphometric characteristics of the basin
included stream order, stream length, bifurcation ratio, drainage density, drainage
frequency, relief ratio, elongation ratio and circularity ratio. The foregoing
analysis clearly indicated by Gwod (2004) for some relations among the various
attributes of the morphometric aspects of the basin and helps to understand their
role in sculpturing the surface of the region.
K.Nookaratnam, Y.K.Srivastava, V.Venkateswararao, E.Amminedu and
K.S.R.Murthy (2005) from Andhra University have already suggested the
methodology of “Check Dam Positioning By Prioritization Of Micro-Watersheds
Using SYI Model And Morphometric Analysis – Remote Sensing And GIS
Prespective.” They prioritized proper sites for check dam construction based on
micro-watershed prioritization using remote sensing data. They have used various
types of remote sensing & GIS data, SOI Topo sheets and NBSS & LUP maps
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which are the basic requirements for carrying out the morphometric analysis and
for estimation of soil erosion. Various thematic maps like LU/LC map, Soil map,
Watershed map, Slope map, Soil erosion map were generated by Arc GIS-9.0
version, which were used in computation of morphometric parameters such as a
bifurcation ratio, drainage density, texture ratio, length of the overland flow,
stream frequency, compactness coefficient, circularity ratio, elongation ratio,
shape factor and form factor. Automated demarcation of prioritization of micro-
watersheds was done by using GIS overlaying technique by assigning weight
factors to all the identified features in each thematic map and ranks were assigned
to the morphometric parameters. Five categories of priority viz. very high, high,
medium, low and very low were given to all the watersheds in both morphometric
analysis and SYI methods. Sixty-two micro-watersheds using SYI method and
twenty-three micro watersheds using morphometric have been prioritized for high
priority. Final priority map had been prepared by considering the commonly
occurring very high prioritized micro watersheds in both SYI and morphometric
analysis. The ranking of micro-watershed directly indicated the soil erosion of
particular micro-watershed under study area.
Nooka Ratnam (2005) aimed for the identification of the proper sites for check
dams construction, based on micro-watershed prioritization by using remote
sensing data, like IRS LISS-III digital data. SOI toposheets of 1:50,000 scales and
other reference maps. With the use of these remotely sensed data and GIS
technique as well as morphometric analysis various thematic maps such as a land
use/land cover, slope drainage, soil had prepared. Morphometric parameters such
as a bifurcation ratio, drainage density, texture ratio, length of the overland flow,
stream frequency, compactness coefficient, circularity ratio, elongation ratio,
shape factor and form factor were computed. Automated demarcation of
prioritization of micro-watersheds was done by using GIS overlaying technique by
assigning weight factors to all the identified features in each thematic map and
ranks were assigned to the morphometric parameters. Five categories of priority
viz. very high, high, medium, low and very low were given to all the watersheds
in both morphometric analysis and SYI methods. Sixty-two micro-watersheds
using SYI method and twenty-three micro watersheds using morphometric have
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been prioritized as very high priority. Final priority map has been prepared by
considering the commonly occurred very high prioritized micro watersheds in
both SYI and morphometric analysis.
Prasad (2006) had worked on the study area of Valagalamanda River rises from
the Valikonda hills and flows eastwards for about 25 KM and joins Swarnamukhi
River at Cheemuru Village. The drainage pattern was dendritic. Quantitative
analysis aspect means morphometric analysis was used for a given drainage
pattern. It was a 6th order basin and elongated in East-West direction. The
bifurcation ratio was 3.8 and hypsometric analysis indicated the mature stage of
development. The stream length ratio was 0.87, area ratio was 4.04, mean
drainage density was 2.41 Km/Sq.Km and stream frequency of the basin was 2.78
per Sq.Km. The general slope of the basin was from West to East. The low slope
regions are potential zones for ground water accumulation.
Jain (2006) selected a study area of Danda Watershed, located in Hindolakhal,
Block of Utterpradesh. The area falls in Survey of India (SOI) Toposheet No. 53
J/12. Details, such as, roads, streams, settlements and spot height, contours etc.
were taken from this toposheet. The Danda watershed had an area of 450.44 ha at
the gauging site (under construction) near Dugyar village. Drainage information
for this map was derived from SOI toposheet and IRS-1C PAN data. In this
watershed, various streams forming a dendritic pattern were presented. The
mapping of drainage pattern was carried out using satellite data. Computation of
the parameters required for morphometric analysis using manual methods like
area measurement using dot grid method or using planimeter and length
measurement using curvimeter were found tedious and time consuming. It is more
difficult if the map is on higher scale like 1:50,000 and 1:25,000. The ordering,
lengths, area and perimeter etc. can be easily estimated using GIS technique. For
quantification of various geomorphological parameters of Danda watershed, the
digitized drainage and interpolated contours maps were used. A database chiefly
derived from remote sensing, on natural resources such as present land use, land
capability, slope, soils, hydro geomorphology were organized in different layers
using Integrated Land and Water Information System (ILWIS) software. An
integrated layer of Composite Land Development Units (CLDU) was created by
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intersecting the resources layers. Sets of decision rules were applied on CLUDs, to
generate action plan map, showing location specific recommendations in the
watershed.
Schmidt et al. (2006) used several computer techniques and models to investigate
the effects of geomorphometry on rainfall-runoff processes at different scales. The
sensitivity of dynamic hydrologic processes to comparatively static boundary
conditions requires different methods for modeling, analysis and visualisation of
different kinds of data. Therefore an approach integrating several
geocomputational concepts, including spatial analysis of different types of geo-
data, static modeling of spatial structures, dynamic 4D-modelling of hydrologic
processes and statistical techniques was chosen. Geomorphometric analysis of the
research areas was carried out with GIS packages (including ARC/INFO and
GRASS), special purpose software and self-developed tools. Soil-morphometric
relationships were modeled within a GIS environment. Hydrologic models (SAKE
and TOPMODEL) were used to simulate rainfall runoff processes. Statistical tools
and sensitivity analysis were applied to gain an insight into the hydrologic
significance of geomorphometric properties.
Price and Leigh (2006) studied the influence of forest conversion on streams of
the southern Blue Ridge Mountains. Two pairs of lightly impacted
(> 90percentage forest) and moderately impacted (70–80 percentage forest) sub-
basins of the upper Little Tennessee River, USA; were identified for comparison.
Reach characteristics (e.g., slope, drainage area, and riparian cover) were aligned
in each pair to isolate contrasting forest cover as the primary driver of any
detected differences in morphology and sedimentology. A suite of standard cross-
sectional and longitudinal data was collected for each reach for characterization of
the sedimentology and morphology of the streams. Difference of means tests was
conducted to identify parameters significantly differing between the lightly and
moderately impacted streams in both pairs.
Amee K. Thakkar, S. D. Dhiman (2007) studied morphometric analysis and
prioritization of mini watersheds in Mohar watershed, Gujarat state, India using
remote sensing and GIS techniques. In this study, morphometric analysis and
prioritization of the eight mini watersheds of Mohr watershed, located between
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Bayad taluka of Sabarkantha district and Kapadwanj taluka of Kheda district in
Gujarat State, India is carried out using Remote Sensing and GIS techniques. The
morphometric parameters considered for analysis are stream length, bifurcation
ratio, drainage density, stream frequency, texture ratio, form factor, circularity
ratio, elongation ratio and compactness ratio. The Mohr watershed has a dendritic
drainage pattern. The highest bifurcation ratio among all the mini watersheds is
9.5 which indicates a strong structural control on the drainage. The maximum
value of circularity ratio is 0.1197 for the mini watershed 5F2B5b3. The mini
watershed 5F2B5a2 has the maximum elongation ratio (0.66). The form factor
values are in range of 0.29 to 0.34 which indicates that the Mohr watershed has
moderately high peak flow for shorter duration. The compound parameter values
are calculated and prioritization rating of eight mini watersheds in Mohr
watershed is carried out.
S. Srinivasa Vittala, S. Govindaiah and H. Honne Gowda (2008) studied the
Prioritization of sub-watersheds for sustainable development and management of
natural resources: An integrated approach using remote sensing, GIS and socio-
economic data. It has been taken up for prioritization based on available natural
resources derived from satellite images and socio economic conditions, including
drainage density, slope, water yield capacity, groundwater prospects, soil,
wasteland, irrigated area, forest cover and data on agricultural labourers, SC/ST
population and rainfall. On the basis of priority and weightage assigned to each
thematic map, the sub-watersheds have been grouped into three categories: high,
medium and low priority.
Akram Javed, Mohd Yousuf Khanday, Rizwan Ahmed, (2009) carried out
prioritization of sub-watersheds based on morphometric and land use analysis
using remote sensing and GIS Techniques. The present study makes an attempt to
prioritize sub-watersheds based on morphometric and land use characteristics
using remote sensing and GIS techniques in Kanera watershed of Guna district,
Madhya Pradesh. Various morphometric parameters, namely linear and shape
have been determined for each sub-watershed and assigned rank on the basis of
value/relationship so as to arrive at a computed value for a final ranking of the
sub-watersheds.
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Sangita Mishra S., Nagarajan R. (2010) had done a case study on Morphometric
analysis and prioritization of sub-watersheds using GIS and Remote Sensing
techniques in Odisha, India. Poor soil cover, sparse vegetation, erratic rainfall and
lack of soil moisture characterize the study area for most part of the year.
Recurring drought coupled with increase in ground water exploitation results in
decline in the ground water level.
Vipul Shinde, K. N. Tiwari and Manjushree Singh (2010) carried out
prioritization of micro watersheds on the basis of soil erosion hazard using remote
sensing and geographic information system. In this study universal soil loss
equation (USLE) interactively with raster-based geographic information system
(GIS) has been applied to calculate potential soil loss at micro watershed level in
the Konar basin of upper Damodar Valley Catchment of India. Micro watershed
priorities have been fixed on the basis of soil erosion risk to implement
management practices in micro watersheds which will reduce soil erosion in
Konar basin.
Dhruvesh P. Patel (2011) used geo-visualization concept for positioning water
harvesting structures in Varekhadi watershed consisting of 26 mini watersheds,
falling in Lower Tapi Basin (LTB), Surat district, Gujarat state. For prioritization
of the mini watersheds, morphometric analysis was utilized by using the linear
parameters such as bifurcation ratio (Rb), drainage density (Dd), stream frequency
(Fu), texture ratio (T), length of overland flow (Lo) and the shape parameter such
as form factor (Rf), shape factor (Bs), elongation ratio (Re), compactness constant
(Cc) and circularity ratio (Rc). The different prioritization ranks were assigned
after evaluation of the compound factor. 3 Dimensional (3D) Elevation Model
(DEM) from Shuttle Radar Topography Mission (SRTM) and DEM from topo
contour were analyzed in Arc Scene 9.1 and the fly tool was utilized for the
Geovisualization of Varekhadi mini watersheds as per the priority ranks.
Combining this with soil map and slope map, the best feasibility of positioning
check dams in mini-watershed no. 1, 5 and 24 has been proposed, after validation
of the sites.
V. B. Rekha, A. V. George and M. Rita (2011) carried out morphometric
analysis and micro-watershed prioritization of Peruvanthanam sub-watershed, the
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Manimala River Basin, Kerala, South India. A critical evaluation and assessment
of morphometric parameters and prioritization of micro-watersheds based on
water holding capacity of Peruvanthanam subwatershed have been achieved
through measurement of linear, aerial and relief aspects of basins by using remote
sensing and GIS techniques, and it necessitates preparation of a detailed drainage
map. For prioritization, 9 micro-watersheds are delineated and parameters such as
Rb, Dd, Fs,T, Lof and C are calculated separately and prioritization has been done
by using the Raster calculator option of Spatial analyst.
Vipul Shinde & Arabinda Sharma & Kamlesh N. Tiwari & Manjushree
Singh (2011) studied Quantitative Determination of Soil Erosion and
Prioritization of Micro-Watersheds Using Remote Sensing and GIS. The present
study focuses application of most widely used Universal Soil Loss Equation
(USLE) to determine soil erosion and prioritization of micro-watersheds of Upper
Damodar Valley Catchment (UDVC) of India. Geographic Information System
(GIS) is applied to prepare various layers of USLE parameters which interactively
estimate soil erosion at micro-watershed level.
Binay Kumar, Uday Kumar (2011) studied micro watershed characterization
and prioritization using Geomatics technology for natural resources management.
A Composite Suitability Index (CSI) has been calculated for each composite unit
by multiplying weightages with rank of each parameter and summing up the
values of all the parameters. Categorization of the CSI is achieved by ranging the
CSI into classes, where each range indicates the amount of limitation acceptable
for each class.
T.A.Kanth and Zahoor ul Hassan (2012) researched on Morphometric analysis
and prioritization of watersheds for soil and water resource management in Wuler
catchment using geo-spatial tools. The quantitative analysis of morphometric
parameters is found to be of immense utility in watershed prioritization for soil
and water conservation and natural resources management at micro level. The
present work is an attempt to carry out a detailed study of linear and shape
morphometric parameters in nineteen watersheds of Wular catchment and their
prioritization for soil and water resource management.
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Santanu Sharma , Trivani Saikia (2012) carried out prioritization of sub-
watersheds in Khanapara–Bornihat Area of Assam–Meghalaya (India) based on
land use and slope analysis using remote sensing and GIS. The present study
makes an attempt to prioritize the sub-watersheds for adopting the conservation
measure. The prioritization is based on land use and slope analysis using Remote
Sensing and GIS techniques in Khanapara–Bornihat area of Assam and
Meghalaya state (India). The study shows the significance changes in land use
pattern especially in settlement and forest lands from 1972 to 2006. Slope map of
the sub-watersheds prepared from the contour values in the toposheets show the
wide variation of slope in the area ranging from 0° to 87°. Based on the
extent/nature of land use/land cover changes over time and land use/land cover—
slope relationship analysis, the sub-watersheds are classified into three categories
as high, medium and low in terms of priority for conservation and management of
natural resources.
Dhurvesh P Patel,Chintan A Gajjar, Prashant K Shrivastav, (2012) carried
out prioritization of mini-watersheds by morphometric analysis using the linear
parameters such as bifurcation ratio, drainage density, stream frequency, texture
ratio, and length of overland flow and shape parameters such as form factor, shape
factor, elongation ratio, compactness constant, and circularity ratio. The different
prioritization ranks are assigned after evaluation of the compound factor. Digital
elevation model from Shuttle Radar Topography Mission, digitized contour and
other thematic layers like drainage order, drainage density, and geology are
created and analyzed over ArcGIS 9.1 platform. Combining all thematic layers
with soil and slope map, the best feasibility of positioning check dams in mini-
watershed has been proposed, after validating the sites through the field surveys.
Ajoy Das, Milan Mondal, Bhaskar Das, Asim Ratan Ghosh (2012) - A case
study had been done by Analysis of drainage morphometry and watershed
prioritization in Bandu Watershed, Purulia, West Bengal through Remote Sensing
and GIS technology. Due to heavy runoff the main problem of this area is scarcity
of water as well as soil erosion. It has been accepted that for sustainable rural
livelihood water and soil conservation is a must. The most suitable way to achieve
this is micro-watershed development. But there is an acute shortage of
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technical manpower to handle such a huge volume of survey related work.
For that reason, application of Remote Sensing and GIS has become a
necessity. Moreover since fund is limited, watershed prioritization is highly
required.
Sridhar. P, Chandra Bose. A.S, Giridhar. M.V.S.S, Viswanadh. G.K (2012) -
Analysed the Prioritization of mini watersheds based on Morphometric analysis
using GIS . The highest Bifurcation ratio is found to be 11.95 for 4E3C5a. The
Maximum values of Circularity ratio of 0.642 and Drainage density of 3.510 have
been found in Lothuvara mini watershed. The Maximum values of Stream
frequency of 7.25 and Texture ratio of 15.81 have been found in Dorlavagu mini-
watershed. Ranks have been assigned to each parameter based on their value with
highest value as I rank and the rank values of all parameters have been cumulated
to obtain compound parameter. Priorities are arrived at based on compound
parameter values. The mini-watershed with the lowest compound parameter value
is given the highest priority and vice versa.
Hasan Raja Naqvi, Laishram Mirana Devi, Masood Ahsan Siddiqui (2012) -
Soil Loss Prediction and Prioritization Based on Revised Universal Soil Loss
Estimation (RUSLE) Model Using Geospatial Technique had been done. The
present study aims to identify the soil loss estimation, to prioritize the micro
watersheds on the basis of mean soil loss values and to suggest best conservation
measures for the Nun Nadi watershed employing Revised Universal Soil Loss
Estimation (RUSLE) model. This micro level study provides accurate results in
the context of soil loss prediction.
Swati Uniyal and Peeyush Gupta, (2013) analysed the Prioritization based on
Morphometric Analysis of Bhilangana Watershed using Spatial technology.
Various morphometric parameters, namely linear and shape have been determined
for each micro-watersheds and assigned ranks on the basis of value/relationship so
as to arrive at a compound value for a final ranking of the watershed. For the
study stream network along with their order was extracted from ASTER DEM 30
m in geospatial environment. Based on morphometric analysis, the watershed has
been classified into three categories as high medium and low in terms of priority
for conservation and management of natural resources.
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7.3 SCOPE AND OBJECTIVE OF THE PRESENT STUDY
A watershed is the surface area drained by a part or the totality of one or several
given water courses and can be taken as a basic erosional landscape element
where land and water resources interact in a perceptible manner (Swati Uniyal
and Peeyush Gupta, 2013). In fact, they are the fundamental units of the fluvial
landscape. A watershed is an ideal unit for management of natural resources like
land and water and for mitigation of the impact of natural disasters for achieving
sustainable development (T.A. Kanth and Zahoor ul Hassan, 2012). Watershed
is an ideal unit for management and sustainable development of natural resources
(Patel et al, 2012). It is a natural hydrological entity which allows surface runoff
to a defined channel, drain, stream or river at a particular point (Chopra et al,
2005). Watershed management is the process of formulation carrying out a course
of action that involves modification in the natural system of watershed to achieve
specified objectives (Johnson et. al. 2002). It further implies appropriate use of
land and water resources of a watershed for optimum production with minimum
hazard to natural resources (Osbrone and Wiley, 1988; Kessler et al, 1992).
Land and Water resources are limited and their wide utilization is imperative,
especially for counties like India, where the population pressure is increasingly
continuous. These resource development programmes are applied generally on
watershed basis and thus prioritization is essential for proper planning and
management of natural resources for sustainable development (S. Srinivasa,
Vittala, S. Govindaiah and H. Honne Gowda, 2008).
Watershed prioritization is the ranking of different micro-watersheds of a
watershed according to the order in which they have to be taken up for
development (Binay Kumar, Uday Kumar, 2011).
Holistic integrated planning, involving remote sensing and GIS has been found to
be effective in planning for regional development based on watershed approach.
Earlier, prioritization of watersheds using remote sensing and Geographical
Information System (GIS) data has been successfully attempted by several
workers. Remote sensing and geographical information system help in the
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190
creation of a database for the watershed which is very much useful for carrying
out spatial analysis thereby helping the decision makers in framing appropriate
measures for critically affected areas (Thakkar and Dhiman 2007; Magesh et al.
2011; Srivastava et al. 2011, 2012a, 2012c, Mukherjee et al. 2007, 2009). It is
an effective tool for integration of spatial data to derive useful outputs and for
modeling (Gupta and Srivastava 2010; Srivastava, et al. 2010; Pandey et al.
2012; Srivastava et al. 2012b, d; Thakur et al. 2012). Nooka Ratnam et al.
(2005) has carried out check dam positioning by prioritization of micro-
watersheds using morphometric analysis. By prioritization of watersheds, one can
conclude which watershed can lead higher amount of discharge due to excessive
amount of rainfall (Thomas et al. 2012). Recently, Patel et al. (2012) has
reported a case study to select suitable sites for water harvesting structures in
Varekhadi Watershed, a part of Lower Tapi Basin (LTB), Surat district, Gujarat
State, India by overlaying of Digital Elevation Model (DEM) and Shuttle Radar
Topography Mission DEM, Soil map and Slope map using RS and GIS approach.
The present study is focused on prioritization of micro-watersheds of Hathmati
watershed of Idar taluka of Sabarkantha district, Gujarat State, India, based on
GIS concept through morphometric analysis. The prioritization concept is helpful
to understand the morphology of individual watersheds (Hlaing et al. 2008;
Javed et al. 2011; Brooks et al. 2006; Strahler 1957), whereas GIS is useful in
positioning the ideal site for water harvesting structure (Gupta et al. 1997;
Chowdary et al. 2009; Kumar et al. 2008), Morphometric analysis and
prioritization of watersheds are very important for water resource modeler and
flood management (Youssef et al. 2011; Miller and Craig Kochel 2010; Bali et
al. 2012).
Through prioritization, prediction and estimation of discharge in a particular
watershed could be calculated during the high rainfall event. The erodibility of
catchment can also be estimated as it is depended on the rainfall and discharge
occurring over a catchment (Bagyaraj et al. 2011; Dawod et al. 2012). These
results are of utmost importance to conserve water and soil and can also be used
for designing efficient water harvesting structures in a watershed. The positioning
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191
of water harvesting structures through GIS and RS will save a lot of expenses,
labor and analysis, particularly for the remote areas. These structures directly
check the excessive water coming from the watersheds and hence lead the soil and
water conservation. Thus, study envisages suitability for water harvesting
structures in watershed, which can help to increase water potential for irrigation
and domestic purpose as well as for controlling the excess runoff which
sometimes takes a form of floods. The study area constitute a part of an arid or
semi-arid region in Gujarat State, India having low rainfall with high intensity of
rainfall were excessive runoff and soil erosion have caused low moisture intake
leading to poor crop production and which needs adoption of soil and water
conservation measures.
The present study aims at identification of suitable sites for water harvesting
structures (Check Dam, Nallah/Gully plugs, and Boulder bunds) based on micro-
watershed prioritization by using remote sensing data, GIS techniques and also
through morphometric studies. The methodology to be adopted is presented in
Fig. 7.1.
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192
Fig. 7.1 : Methodology for Location of Water Harvesting Structures
Chapter 7 : Prioritization of Micro-Watersheds
193
7.4 STUDY AREA
The Hathmati watershed of Idar taluka of Sabarkantha district is selected as a
study area having 1082.62 km2 areas. Hathmati River is the principal tributaries of
Sabarmati river. The Hathmati River rises from the Gujarat Malwa hills south
western foothills of the Rajasthan range near Godad at north latitude of 23°55' and
an east longitude of 73°29' in Sabarkantha district. After traversing a course of 98
km, it meets the Sabarmati River near Ged, 20 km south west of Himatnagar in
Sabarkantha district. The two main tributaries of Hathmati are Bodoli and Guhai
having catchment areas of 119 km2 and 505 km2, respectively. The average annual
rainfall in the catchment is 860 mm. The study areas falls in Survey of India (SOI)
Topographical maps (Toposheets) No. 46-A-13, 46-A-14, 46-E-01, 46-E-02, 46-
E-05 and 46-E-06. Following table shows general features of the Hathmati basin.
Table 7.1 General Features of Hathmati Watershed
Geology Rocks followed by alluvial plains
Physiography Gently sloping pediments to gently sloping
alluvial plain
Runoff High to low
Water Holding Capacity Good
Groundwater Formation Semi confined to and unconfined aquifers
Irrigability Good
Forests Traditionally well forested, now degraded
Main Community Caste based agrarian communities
dominated by Patidars and Chowdharies
The Wet seasons sets in by the middle of June and withdraws by the middle of
October. About 90% of the rainfall occurs during the Wet season (June-October)
and during the rest of the year (dry season) there is very little rainfall with no
regular pattern. Typical tropical climate prevails in the basin for better part of the
year. For practical considerations two seasons dry (December-May) and Wet
(June-November) seasons exist in the area. Mean annual runoff in the catchment
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194
is 123 Mm3. The catchment is of "leaf or fern type" which is having gently sloping
pediments to gently sloping alluvial plain. The river basin has various land use
patterns, of which agricultural land use (double crop-35%; single crop-25%),
forests (15%), waste land (15%) and mixed land use (10%) are the important land
use classifications. Number of villages under submergence is one partial and six
full. The river and its tributaries flow through different terrain having varied land
use activities, soil conditions, vegetation and agricultural practices. The water
potential of the river Hathmati is mainly used for drinking, industries, irrigation
and flood control. Refer location maps (Fig. 7.2 to 7.4)
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Fig: 7.2 Location Map
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Fig: 7.3 District Map
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Fig. 7.4 Taluka Map
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Fig: 7.5 Hathmati River map
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7.5 GENERATION OF THEMATIC MAPS
As a scientific study of the earth advanced, so new material needed to be mapped.
The developments in the assessment and understanding of natural resources like
Geology, Geomorphology, Soil science, Ecology, and Land that began in the 19th
century and have continued to this day provided new material to be mapped.
Whereas topographical maps can be regarded as general purposes because they do
not set out to fulfill any specific aim (i.e., they can be interpreted for many
different purposes), maps of the distribution of rock types, soil series or Landuse
are made for more limited and specific purposes.
The specific purposes maps are often referred to as “Thematic” maps because they
contain information about a single subject or themes. To make the thematic data
easy to understand, thematic maps are commonly drawn over a simplified
topographic base by which user can orient themselves.
Various thematic maps were prepared for the study area from SOI Toposheet,
Satellites data and other ancillary data. These maps have been prepared at
1:50,000 scales. These have been compiled and studied individually as well as in
relation to each other.
7.6 GENERAL METHODOLOGY FOR PREPARATION OF
THEMATIC MAPS:
Various thematic maps were prepared for the study area from SOI Toposheets,
Satellites data and other ancillary data. These maps have been prepared at
1:50,000 scales. In this study, IRS P6 PAN + LISS IV geocoded data were used.
With the help of image interpretation or recognition element such as tone, texture,
size, shape, association, feature, etc. various thematic classes were identified and
verified with the ground truth. The interpreted thematic details were transferred
and finally the following particular thematic maps were prepared.
Base map
Drainage map
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Watershed map
Slope map
Land use/Land cover map
Contour map
Elevation map (DEM)
7.6.1 Base map
This map is prepared directly from the SOI Toposheets maps Fig. 7.6 and 7.7
which is used to derive the basic information of the study area such as Road
networks, Rail networks, River, Settlements, Tanks, Canals, etc. This information
is updated with the Satellite images. The basic information thus prepared shows
the study area boundary and other information.
7.6.2 Drainage map
Drainage map of the study area has been delineated using Toposheet and satellite
imagery. All the drainages were traced out and map was prepared. Then this
drainage is super imposed with satellites images data and the changes in the
drainage courses were mapped. The drainage map was shown in Fig. 7.8. The
drainage map has been later used to delineate watershed boundaries.
7.6.3 Watershed map
Watersheds are natural hydrological entities that cover a specific areas extent of
landform which rainwater flow to a defined gully, stream or river at any particular
point. The size of the watershed depends upon the size of the stream or river and
the point interception of the streams or river and density and distribution of
drainage.
The All India Soil and Land Use Survey, Ministry of Agriculture and cooperation
(AIR & LUS), New Delhi, have developed system watershed delineation like
water resources Region, Basin, Catchments, Sub catchments and watershed. The
surface water bodies have been studied and delineated using satellite imagery.
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Watershed boundaries are delineated using drainage and surface water bodies’
maps. Drainage map with the details of water bodies and watershed boundary is
shown in Fig. 7.9. Table 7.2 shows the watershed wise area.
Table 7.2 : Watershed wise areas
Sr.No. Watershed Code Area (Sq.Km.)
1 MW 1 73.70
2 MW 2 72.72
3 MW 3 54.47
4 MW 4 38.56
5 MW 5 137.00
6 MW 6 106.41
7 MW 7 56.50
8 MW 8 90.80
9 MW 9 66.82
10 MW 10 138.65
11 MW 11 59.05
12 MW 12 25.64
13 MW 13 162.30
Total 1082.62 km2
7.6.4 Slope map
Slope is a very important factor for watershed prioritization. If the slope is higher
degree there is a chance for more run off, infiltration is less, and automatically
erosion is more. In the present study slope is prepared using SRTM data. Slopes
study classified on the basis of the guidelines mentioned in Integrated Mission for
Sustainable Development (IMSD) document. Finally, slope coverage has been
readied as one of the coverage in the integrated analysis. The study area is found
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to be very gently sloping. The slope map is shown in Fig. 7.10, Table 7.3 show
the different slope categories obtained and their areal distribution in the study
area.
Table 7.3 : Percent are under various slope classes
Slope class Slope category Slope %)
1 Nearly level 0 – 1
2 Very gently sloping 1 – 3
3 Gently sloping 3 – 8
4 Moderately sloping 8 – 15
5 Strongly sloping -
6 Moderately steep to steeply sloping -
7 Very steep sloping -
7.6.5 Land use /Land cover map
To evaluate the land use /land cover condition of the study area satellite imagery
is used. The interpretation and correlation of imagery with object involved the
comparison of spectral response of each type of object with tinge characteristics.
Monoscopic visual interpretation of IRS-P6 LISS III geo-coded FCC of 2010 on
1:50,000 scales are done for identification of different land use/land cover classes.
The interpreted details are checked on ground to verify the Interpretation and
doubtful areas. Based on the ground verification, boundaries of the different land
use/ land cover units are finalized. Double-cropped area is largely lying in areas
where irrigation facilities are available. The land use/land cover map is shown in
Fig.7.11. Various land use categories present in the study area are described
below:
Habitation:
This class of land is identified as mixed type of residential urban or rural cover,
which includes low rise and detached buildings and slums. Here industrial area is
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203
found as the main business for the people living there. Habitation is identified as
mottled gray with coarse texture.
Agriculture land :
This class of land is broadly defined as the land, which is used primarily for
production of field crops. Tobacco, paddy, wheat, etc. are the major crops grown
in the study area. Agricultural land is further classified into (a) double cropped
(Kharif and Rabi) area, (b) single cropped (Kharif) area. Double cropped area is
defined as the area, which is cultivated more than once in a year. Single cropped
area is defined as the area, which is cultivated during one season in the year,
agriculture land is identified mainly on basis of pinkish- red tone, fine texture and
its pattern.
Waste land
Wasteland can be broadly defined as the land which is degraded due to various
factor such as erosion, salinity, water –logging, mining, desertification, etc., there
by a posing problem to ecological balance in that area. Wasteland is further
classified into:
(a) Waste land with scrub
(b) Waste land without scrub
Wasteland with scrub is area with scant scrub vegetation. Wasteland without scrub
in the study area is an area without any vegetation.
Water bodies
This class of land includes ponds, lakes, depression storage, perennial
rivers/stream, etc. water bodies are identified mainly on the basis of dark
blue/black tone.
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Fig. 7.6 Grid Map
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Fig. 7.7 Toposheets Map
Chapter 7 : Prioritization of Micro-Watersheds
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Fig. 7.8 Drainage Order Map
Chapter 7 : Prioritization of Micro-Watersheds
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Fig. 7.9 Watershed map
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Fig 7.10 Slope map
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Fig. 7.11 Land use / Land cover Map
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Fig. 7.12 Contour Map
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Fig. 7.13 DEM Map
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212
7.7 MORPHOMETRIC ANALYSIS
Morphometric analysis of a watershed provides a quantitative description of the
drainage system, which is an important aspect of the characterization of
watersheds (Strahler, 1964). Morphometric analysis refers to the quantitative
analysis of form, a concept that encompasses size and shape. Morphometric
analysis requires measurement of linear features, areal aspects, gradient of channel
network and contributing ground slopes of the drainage basin (Nautiyal, 1994).
The morphometric assessment helps to elaborate a primary hydrological diagnosis
in order to predict approximate behaviour of a watershed if correctly coupled with
geomorphology and geology (Esper, 2008). The hydrological response of a river
basin can be interrelated with the physiographic characteristics of the drainage
basin, such as size, shape, slope, drainage density and size, and length of the
streams, etc. (Chorley, 1969, Gregory and Walling 1973). Hence, morphometric
analysis of a watershed is an essential first step, towards basic understanding of
watershed dynamics. Morphometric is the measurement and mathematical
analysis of the configuration of the earth's surface, shape and dimensions of its
land forms (Clarke, 1996). The morphometric characteristics at the watershed
scale may contain important information regarding its formation and development
because all hydrologic and geomorphic process occur within the watershed
(Singh, 1992). This analysis can be achieved through measurement of linear,
aerial and relief aspects of basins by using the approach of remote sensing and
GIS.
Remote sensing and GIS techniques are currently used for assessing various
terrain and morphometric parameters of the drainage basins and watersheds, as
they provide a flexible environment and a powerful tool for the manipulation and
analysis of spatial information satellite remote sensing has the ability of obtaining
synoptic view of large area at one time and very useful in analyzing the drainage
morphometric (Swati Uniyal and Peeyush Gupta, 2013). Pioneering work on the
drainage basin morphometric has been carried out by Horton (1932, 1945),
Miller (1953), Smith (1950), Strahler (1964) and others. In India, some of the
recent studies on morphometric analysis using remote sensing technique were
carried out by Nautiyal (1994), Srivastava (1997), Nag (1998), Shrimali et al.
Chapter 7 : Prioritization of Micro-Watersheds
213
(2001), Khan et al. (2001), Srinivasa et al. (2004). Chopra et al. (2005) have
carried out morphometric analysis of sub-watersheds in Gurdaspur district,
Punjab. A study on characterization and management of watersheds in
Ganeshapur watershed of Nagpur district was carried out by Solanke et al.
(2005).
Prioritization of sub-watersheds based on morphometric analysis of drainage
basins using RS and GIS techniques, was attempted by Biswas et al. (1999).
Nooka Ratnam et al. (2005) carried out check dam positioning by prioritization
of micro-watersheds using Silt Yield Index (SYI) model and morphometric
analysis using RS and GIS in Midnapur district of West Bengal. Arun et al.
(2005) attempted a rule based physiographic characterization of draught prone
watershed applying remote sensing and GIS techniques in Gandeshwari watershed
in Bankura district of West Bengal. Amee and Dhiman (2007) have carried out
morphometric analysis and prioritization of eight mini watersheds of Mohr
watershed, located between Bayad taluka of Sabarkantha district and Kapadwanj
taluka of Kheda district in Gujarat State, India using RS and GIS techniques.
More recently, Dhruvesh Patel, Chintan Gajjar and Prashant Srivastava
(2012) have carried out morphometric analysis and prioritization of ten mini-
watersheds of Malesari Watershed, situated in Bhavnagar district of Saurashtra
region of Gujarat state, India using RS and GIS techniques. In the present study,
morphometric and land use/land cover analysis have been carried out in Hathmati
Watershed of Sabarkantha district, Gujarat state, India using remote sensing and
GIS techniques.
7.8 MORPHOMETRIC PARAMETERS
The drainage basin morphometric study has to pass through the most important
stage called stream ordering. Various methods have been suggested for this
purpose, but the most popular and most simple ordinal scale of stream ordering
used by Strahler 1964 is being followed here. The characteristics of a basin and of
the streams making up the drainage system can be represented quantitatively using
indices of basin shape and relief and of linkage in the channel network. Many of
the indices are ratios, meaning that they can be used to characterize and compare
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214
basins of different sizes. The details of the drainage morphometric parameters of
the main basin are presented below.
7.8.1 Characteristics of Catchments
The hydrologic behavior of a catchment depends on certain characteristics of the
drainage basin. These characteristics are mainly related to the physical drainage
basin or to the channel. The physical characteristics of a catchment are drainage
area, its shape, slope, centroid etc. The channel characteristics are channel order,
its length, slope, profile and drainage density. Many of these characteristics can be
determined easily with the aid of computers.
7.8.1.1 Drainage-Area Characteristics
The drainage–area characteristics of the basin, as under, are determined from the
Topographic maps, soil maps, crop reports and reconnaissance of the area, i)
proportion of catchment under cultivation, ii) culture, kind and extent of crops
grown, etc, iii) area under forests, iv) grassland area, v) area under habitation,
town and cities.
7.8.1.2 Basin Order and Channel Order
The concept of channel order was introduced by Horton and Strahler to describe
the basins in quantitative terms. This concept is used with the linear dimension of
the channel length. The stream orders are designated to the available channel
network. The first order stream has no tributary. Its flow depends entirely on the
surface overland flow to it (Fig.7.14). The second-order channel is formed by the
junction of two first-order channels and as such has higher surface flow.
Chapter 7 : Prioritization of Micro-Watersheds
215
Fig. 7.14 Channel order
Likewise, the third-order channel receives flow from two second-order channels
and may in addition receive flow from first order channel or second-order channel
which empty directly into it. Thus the drainage basin is described as first, second,
or higher order depending upon the stream order at the outlet. The order of the
basin is the order of its higher-order channel.
7.8.1.3 Basin Area
The flow from a drainage basin is a function of the area of the basin. Basin area is
the area contained within the vertical projection of the drainage divide on a
horizontal plane. It is measured in square kilometer, hectares. The closed drainage
areas such as swamps, lakes that do not contribute runoff to the drainage system
are excluded from the total drainage area to get the affective drainage area.
Likewise, there may be underground leakage from one basin to another which
means larger affective drainage area from the leakage is transmitted. The area of a
basin of a given order is computed by drawing the perimeter of all first, second
and higher order of basins on the topographic map of the basin. The flow from a
basin is related to the area by the relation Q = CAm . It is a very simple but
important relation between the drainage area and discharge.
7.8.1.4 Basin Shape
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216
The catchments may be of symmetrical or irregular forms. The shape may
resemble a Pear shape, U-shape or a V-shape valley as shown in Fig. 7.15 a,b & c.
Fig. 7.15 Basin shapes.
The shape characteristics of a catchment are generally expressed by form factor
and compactness coefficient.
(a) Form factor, Ff
The form factor is an index expressing the relation of average width to the axial
length of basin, to measure the shape characteristics.
2
/
lA
llA
lBFf (7.1)
Where, l = axial length from outlet to the remotest point in the basin, and B=
average width obtained by dividing the area (A) by axial length.
(b) Compactness coefficient, Cc
It is the ratio of perimeter of the catchment to the circumference of a circle whose
area is equal to that of the catchment. This coefficient is independent of the size of
the catchment and is dependent only on the shape.
sin
sin
BaofareathetoequalisareawhosecircleofnceCircumfereBaofPerimeterCc (7.2)
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217
5.02821.0
22 AP
RP
APCc
(7.3)
Where, P = perimeter of basin (km) , A = area of basin (sq. km) and R = radius of
the circle of equivalent area(km).
(c) Elongation Ratio, Re.
Re is defined as the ratio of basin area to the area of circle having the same
perimeter as the basin = 2R/L. The values vary between 0.2 to 0.8.
502 .
be /A
LR (7.4)
Where, Lb is the maximum length (ft) of the basin parallel to the principal
drainage lines.
(d) Basin Length, Lb
Lb is the longest dimension of a basin parallel to its principal drainage channel.
Lb= 1.312A0.568 (7.5)
7.8.2 Drainage Density
Drainage density is expressed as total length of all streams, perennial and
intermittent, per unit area of the basin. It is an index of the a real channel
development in the catchment
Dd = L/A (7.6)
Where, Dd is drainage density (km/sq km), L is total length of all streams in the
catchment (km) and A is area of catchment (km2).
High value of density indicates well developed network and torrential runoff
likely to cause violent flood, while a low value signifies a less developed network
and a modest runoff which is explained by high permeability of the terrain.
Chapter 7 : Prioritization of Micro-Watersheds
218
7.8.3 Average Altitude
Elevation of the basin varies from point to point. The average elevation or altitude
is computed by multiplying each increment of area by its mean elevation and the
sum of the product divided by the drainage area. The weighted mean altitude is
determined by dividing the sum of the product of contour length and respective
elevations by the total length of contours. In the case of large basins, depending on
the scale, the area s divided into square of suitable size, say 1 to 250 km sides and
the elevations at the intersections of all squares are tabulated and averaged. The
median elevation or the elevation at 50 percent area of the catchment is
determined from the area-elevation curve called Hypsometric curve (Fig. 7.16)
The area-elevation curve is obtained by plotting elevation against area, or
percentage of area, above or below a given elevation.
Fig. 7.16 Hypsometric curve
7.8.4 Average Land Slope
The slope of the catchment varies from point to point. The average slope is equal
to the total length of contours multiplied by the contour internal and divided by
Chapter 7 : Prioritization of Micro-Watersheds
219
the area of the catchment. It is a laborious method. The land slope is determined
from a grid established on the contour plan of the catchment generally in north-
south and east-west lines. For smaller catchments of 250 sq.km or less minimum
four grid lines crossing the basin in each direction are required, for large
catchments-more grid lines are required than those indicated for smaller
catchments, and for very large catchments-at least one grid in each direction for
each 250 sq.km of catchment area is required. The length of each line is measured
and number of contours crossed counted. According to Horton, the area whose
slope is to be determined I sub-divided by a grid into a number of squares of equal
size. The number of contours crossed by each sub-dividing line is counted and the
lengths of the grid lines are scaled. The slope of the catchment is given by the
relation,
S = DN/L (7.7)
Where, S = slope of catchment, D = contour interval, N = number of contours
crossed by all the sub-dividing lines, and L = total length of the sub-dividing lines.
7.8.5 Average Stream Slope
Average stream slope is determined by tabulating lengths and elevations of the
stream channel and its major tributaries and a properly weighted mean slope is
computed. Usually, it is taken as total fall between the points divided by the
stream length. A better and realistic mean stream slope is that which has the same
area under it as does the profile.
7.8.6 Basin Centroid
It is the location of the point within the drainage basin that represents the weighted
centre of the basin. It is the first moment of the area about the origin.
7.8.7 Basin Similarity
The drainage-basin similarity may be (i) geometric similarity (i.e., in terms of
basin area, shape, main channel slope, topography), (ii) hydrologic similarity (i.e.,
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220
in terms of snowfall, rainfall, runoff, infiltration, valley storage), and (iii) geologic
similarity (i.e., relating to ground water flow, soil erosion, sediment
characteristics).
7.8.8 Channel Length
It is the length of channels of each order. The first order channels are of short
length and the length increases geometrically, as the order Increases.
7.8.9 Channel Profile
It represents the relationship between the altitude and horizontal distance. It is
determined from topographic map of a basin. Generally the channel profile is
concave upward. The concavity is a function of the basin geology and
precipitation. The upper part of the channel profile is generally steeper than the
lower portion in a drainage basin of fairly uniform geology.
7.8.10 Overland Flow Length
The maximum length of surface flow traversed by rain water flow towards a
channel is called length of overland flow (Lo).
Lo = 1/2Dd, (7.8)
Where Lo is length of overland flow, (km) and Dd is drainage density (km-1).
7.8.11 Drainage Pattern
The pattern of the tributary system depends on various factors such as physical
characteristics of the area, nature of rock formation and their erodibility. The
drainage pattern may be classified, as under, depending on the shape of the
catchment and stream pattern.
1. Tree-like Type
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In homogeneous rocks structure regions there is little variation in the
resistivity of the rock to influence stream pattern, the resulting streams
running in all directions are called dendrites or tree-like type (Fig. 7.17).
2. Rectangular Type.
The region with many rectangular joints and faults results in a system of
valleys joining at nearly right angles. Such a drainage pattern is termed as
rectangular type. It follows no rule with regard to the size and direction of the
stream. Usually it shows two directions, nearly at right angles to each other
(Fig.7.18) and as such there are numerous right angle turns in the river
course, with the tributaries discharging perpendicularly into the next larger
generation.
Fig. 7.17 Tree Type. Fig.7.18 Rectangular Type.
3. Radial Type
It represents the drainage pattern wherein a number of streams usually radiate
outward from a central focus (Fig.7.19). Adjacent channels emptying into
each other form streams system which individually tend to be of parallel type.
Chapter 7 : Prioritization of Micro-Watersheds
222
Fig. 7.19 : Radial Type
4. Trellis Type
In the region where the underlying rock is strongly folded or sharply dipping
a trellis type drainage pattern is developed. The characteristic of the pattern is
that the orientation followed by some streams is towards one side and by
others to the opposite side. The orientation of the other streams being at right
angle to this, likewise towards two directions (Fig.7.20). A simple form of
trellis pattern is called annular pattern wherein the subsequent streams which
form in the weaker strata of a dome mountain define a roughly circular, or
annular pattern. The longer streams are subsequent and follow weaker rock
strata, while the shorter tributaries are either obsequent or resequent.
5. Parallel Type
In this pattern of catchment (Fig.7.21) both the main stream and tributaries
are in parallel because of pronounced inclination or internal geological
structure of the region.
Chapter 7 : Prioritization of Micro-Watersheds
223
Fig. 7.20 Trellis Type. Fig. 7.21: Parallel Type.
7.8.12 Classification of Catchments
Large river basins usually tend to be of fan-shaped or pear-shaped but smaller
basins exhibit greater variation in shape depending on the geological structure of a
basin. The two usual classifications of the catchments are fern-leaf type and fan-
shaped type.
1. Fern-leaf Type.
The fern-leaf type catchment is relatively narrow (Fig.7.22) possessing the
main characteristics such as (i) indicative of smaller peak discharge, (ii) the
discharges are likely to be distributed over a longer period of time, (iii) the
tributaries meet the main stream at almost regular intervals, and (iv) the
tributaries are generally of different sizes and lengths, (v) the peak of the
flood runoff reaches a point on the main stream at different times resulting in
smaller floods.
Chapter 7 : Prioritization of Micro-Watersheds
224
Fig. 7.22 Fern-leaf shaped catchment
2. Fan-shaped Type
The fan-shaped type catchment, as the name implies, extends in the shape of
a fan from a point and is wider (Fig.7.23) possessing the main characteristics,
(i) indicative of incidence of high floods, (ii) time of concentration of runoff
is nearly the same in all tributaries, (iii) the tributaries are nearly of the same
size, (iv) the peak flood from the various tributaries reaches the main stream
approximately at the same time, (v) and the tributaries meet the main stream
approximately at the same place.
Fig. 7.23 Fan-shaped catchment
7.8.13 Classification of Streams
Chapter 7 : Prioritization of Micro-Watersheds
225
The streams are classified according to the base flow components of their
discharge, as under:
7.8.13.1 Perennial Stream
The stream which flows all the year round is called perennial stream. The flow in
non monsoon season may be due to ground water regeneration or snow melt in
high altitudes. The stream bed is below the ground water table to collect ground
water.
7.8.13.2 Intermittent Stream
The stream which flows during monsoon and by regeneration of ground water but
dry up practically in summer is called intermittent stream. The stream bed is
intermittently below the ground water table in wet season and drops below the
water table in dry season
7.8.13.3 Influent stream
The stream which has its bed level lower than ground water table so that seepage
from it feeds the ground water table is termed as influent stream.
7.8.13.4 Effluent Stream
The stream which has bed level lower than ground water table and is fed by high
water table is called effluent stream. Most of the perennial rivers belong to this
category, the base flow being the effluent seepage from the catchment.
7.8.13.5 Ephemeral Stream
The stream which flows only during storm runoff of short duration, as in arid
regions, and dry up completely in non-monsoon period is called ephemeral
stream. A stream which is perennial, intermittent or ephemeral throughout its
course is termed as continuous. The stream which changes its classification in
various reaches of its course is called an interrupted stream.
Chapter 7 : Prioritization of Micro-Watersheds
226
Table 7.4 Morpho Metric Parameters
1 568.0b A312.1L Basin Length
2 A
LDd Drainage Density
3 A
NFu Stream Frequency
4 do D2
1L Length of The Overland Flow
5 1u
ub N
NR
Bifurcation Ratio
6 b
fL
AR Form Factor
7 A
LB
2b
s Shape Factor
8 5.0
be
/A
L/2R
Elongation Ratio
9 22c P
A57.12
P
A4R
Circularity Ratio
10 5.0c A
P2821.0C Compactness Ratio
11 P
NT 1 Texture Ratio
Chapter 7 : Prioritization of Micro-Watersheds
227
Where,
Lb : Basin Length Is In Km
A : Area of the Basin in Km2
P : Perimeter in Km
Dd : Is the Drainage Density
L : Is the Total Length of All Channels of All Order In The Drainage Basin
N : Total no. Of Streams
N1 : Total No. Of First Order Streams
Lo : Length of the Overland Flow In Km
Rb : Bifurcation Ratio
Nu : No. Of Streams of Order
Nu+1 : No. Of Streams of Next Higher Order
Rf : Form Factor (Rf<1)
Bs : Shape Factor (Bs>1)
Re : Elongation Ratio (Re<=1)
Rc : Circularity Ratio (Rc<=1)
Cc : Compactness Coefficient (Cc>=1
Chapter 7 : Prioritization of Micro-Watersheds
228
Table 7.5 : Description of Indicators of Prioritization
Parameter Characteristics
Linear
Stream Order It is defined as a measure of the position of a stream in the hierarchy of tributaries.
Mean Stream Length (Lsm) The mean stream length is the characteristic property related to the drainage network and its associated surfaces. Generally higher the order, longer the length of streams is noticed in nature.
Drainage Texture (T) It is the total number of stream segments of all orders per perimeter of the area
Bifurcation Ratio (Rb) Bifurcation ratios characteristically range between 3.0 and 5.0 for basins in which the geologic structures do not distort the drainage pattern.
Drainage Density (Dd) Drainage density (Dd) shows the landscape dissection, runoff potential, infiltration capacity of the land, climatic conditions and vegetation cover of the basin. High drainage density is the resultant of weak or impermeable subsurface material, sparse vegetation and mountainous relief. Low drainage density leads to coarse drainage texture while high drainage density leads to fine drainage texture.
Stream Frequency (Fs) Stream Frequency is the total number of stream segments of all orders per unit area. Generally, high stream frequency is related to impermeable sub-surface material, sparse vegetation, high relief conditions and low infiltration capacity.
Shape
Form Factor (Ff) Form factor is defined as ratio of basin area to the square of basin length The value of form factor would always be less than 0.7854 (for a perfectly circular basin) Smaller the value of form factor, more elongated will be the basin. The basins with high form factors have high peak flows of shorter duration, whereas, elongated watershed with low form factors
Chapter 7 : Prioritization of Micro-Watersheds
229
have lower peak flow of longer duration.
Circulatory Ratio (Rc) It is defined as the ratio of basin area to the area of circle having the same perimeter as the basin and is dimensionless. Circulatory Ratio is helpful for assessment of flood hazard. Higher the Rc value, higher is the flood hazard at the peak time at the outlet point.
Elongation Ratio (Re) Elongation ratio (Re) is defined as the ratio of diameter of a circle of the same area as the basin to the maximum basin length. It is a very significant index in the analysis of basin shape which helps to give an idea about the hydrological character of a drainage basin. Values near to 1.0 are typical of regions of very low relief
Compactness Co efficient (Cc) Compactness Co efficient (Cc) is used to express the relationship of a hydrological basin with that of a circular basin having the same area as the hydrologic basin.
7.9 METHODOLOGY AND APPLICATION
The remote sensing image presented in chapter 2, is geometrically rectified with
respect to Survey of India (SOI) topographical map on 1:50,000 scale. The
drainage pattern was initially derived from SOI toposheet and later updated using
linearly stretched False Color Composite (FCC) IRS-P6 LISS IV satellite data.
Some of the first order drainage streams were updated from satellite data. The
drainage pattern delineated for watershed was exported to ARC/INFO GIS
software for morphometric analysis. For better accuracy of the thematic map,
ground truth check is done for verification and necessary modifications are made
in thematic maps during post interpretation.
The various morphometric parameters such as area, perimeter, stream order,
stream length, stream number, bifurcation ratio, drainage density, stream
frequency, drainage texture, length of basin, form factor, circulatory ratio,
Chapter 7 : Prioritization of Micro-Watersheds
230
elongation ratio, length of overland flow, compactness coefficient, shape factor,
texture ratio were computed based on the formula suggested by (Horton, 1945),
(Strahler, 1964), (Schumm, 1956), (Nooka Ratnam et al. 2005) and (Miller,
1953) given in Table 7.4.
The stream ordering is carried out using Horton's law. The fundamental
parameters namely; stream length, area, perimeter and number of streams are
derived from the micro watershed layer and basin length was calculated from the
stream length. Bifurcation ratio was calculated from the number of streams. The
other parameters were calculated from area, perimeter, basin length and stream
length.
The linear parameters such as drainage density, stream frequency, bifurcation
ratio, drainage texture, length of overland flow have a direct relationship with
erodibility, higher the value, more is the erodibility. Hence for prioritization of
micro-watersheds, the highest value of linear parameters was rated as rank 1,
second highest value was rated as rank 2 and so on, and the least value was rated
as last in rank. Shape parameters such as elongation ratio, compactness
coefficient, circularity ratio, basin shape and form factor have an inverse
relationship with erodibility (Nooka Ratnam et al., 2005), lower the value, more
is the erodibility. Thus the lowest value of shape parameters was rated as rank 1,
next lower value was rated as rank 2 and so on and the highest value was rated last
in rank. Hence, the ranking of the micro watersheds has been determined by
assigning the highest priority/rank based on highest value in case of linear
parameters and lowest value in case of shape parameters.
The prioritization was carried out by assigning ranks to the individual indicators
and a compound value (Cp) was calculated. Watersheds with highest Cp were of
low priority while those with lowest Cp were of high priority. Thus an index of
high, medium and low priority was produced. Prioritization rating of all the
thirteen micro-watersheds of Hathmati watershed was carried out by calculating
the compound parameter values.
Chapter 7 : Prioritization of Micro-Watersheds
231
Table 7.6 Stream Order of Sub-watershed
Watershed Code No.
1st
Order 2nd
Order 3rd
Order 4th
Order 5th
Order 6th
Order
Total No. of
Streams
MW 1 114 61 31 17 – – 216
MW 2 191 105 39 28 – – 355
MW 3 82 40 30 10 2 – 151
MW 4 70 31 9 20 19 – 147
MW 5 202 95 40 33 20 – 388
MW 6 128 69 37 6 26 – 261
MW 7 59 37 10 2 13 – 116
MW 8 118 68 30 15 2 9 239
MW 9 27 15 7 7 – – 56
MW 10 178 85 69 15 15 5 359
MW 11 42 24 3 14 – – 81
MW 12 45 24 13 7 – – 89
MW 13 241 112 54 18 55 – 478
Chapter 7 : Prioritization of Micro-Watersheds
232
Table 7.7 Morphometric Parameters
Micro- Water-
shed Code No.
Area (A) km2
Peri-meter
(P) km
Total Length of all
streams of all
orders (L) Km
Total No. of
Streams (N)
Total No. of First
orders streams
(N1)
Basin Length
(Lb) km
Bifur-cation ratio (Rb)
Drain-age
Density (Dd) Km/ Km2
Stream Fre-
quency (Fu)
No/Km2
Texture ratio (T)
Length of
overland flow (LO)
Form factor (Rf)
Shape factor (Bs)
Elong-ation ratio (Re)
Compactness
coefficient (Cc)
Circularity ratio (Rc)
MW 1 73.70 57.10 131.75 216 114 15.089 1.887 1.788 2.931 1.996 0.894 0.324 3.089 0.642 1.876 0.284
MW 2 72.72 71.96 189.98 355 191 14.975 1.968 2.612 4.882 2.654 1.306 0.324 3.084 0.642 2.380 0.177
MW 3 54.47 45.08 98.24 151 82 12.708 2.846 1.804 2.772 1.819 0.902 0.337 2.965 0.655 1.723 0.337
MW 4 38.56 64.88 91.05 147 70 10.444 2.059 2.361 3.812 1.079 1.181 0.354 2.829 0.671 2.947 0.115
MW 5 137.00 110.85 234.43 388 202 21.458 1.841 1.711 2.832 1.822 0.856 0.298 3.361 0.615 2.672 0.140
MW 6 106.41 85.75 175.07 261 128 18.589 2.529 1.645 2.453 1.493 0.823 0.308 3.247 0.626 2.345 0.182
MW 7 56.50 64.18 80.90 116 59 12.975 2.612 1.432 2.053 0.919 0.716 0.336 2.980 0.653 2.409 0.172
MW 8 90.80 86.11 146.59 239 118 16.987 2.001 1.614 2.632 1.370 0.807 0.315 3.178 0.633 2.549 0.154
MW 9 66.82 58.70 56.16 56 27 14.272 1.648 0.840 0.838 0.460 0.420 0.328 3.048 0.646 2.026 0.244
MW 10 138.65 104.14 215.74 359 178 21.605 2.642 1.556 2.589 1.709 0.778 0.297 3.366 0.615 2.495 0.161
MW 11 59.05 46.67 69.81 81 42 13.304 3.321 1.182 1.372 0.900 0.591 0.334 2.997 0.652 1.713 0.341
MW 12 25.64 42.08 55.50 89 45 8.283 1.859 2.165 3.471 1.069 1.082 0.374 2.676 0.690 2.344 0.182
MW 13 162.30 109.79 133.04 478 241 23.626 1.888 0.820 2.945 2.195 0.410 0.291 3.439 0.608 2.431 0.169
Chapter 7 : Prioritization of Micro-Watersheds
233
Table 7.8 Compound Value of Morphometric Parameters
Watershed Code No. Rb Dd Fu T Lo Rf Bs Re Cc Rc (=Sum)
Compound Value (Cp) Rank
MW 1 10 5 5 3 5 7 8 6 3 11 63 6.3 4
MW 2 8 1 1 1 1 6 7 7 7 7 46 4.6 1
MW 3 2 4 7 5 4 11 3 11 2 12 61 6.1 2
MW 4 6 2 2 9 2 12 2 12 13 1 61 6.1 3
MW 5 12 6 6 4 6 3 11 3 12 2 65 6.5 5
MW 6 5 7 10 7 7 4 10 4 6 8 68 6.8 7
MW 7 4 10 11 11 10 10 4 10 8 6 84 8.4 11
MW 8 7 8 8 8 8 5 9 5 11 3 72 7.2 10
MW 9 13 12 13 13 12 8 6 8 4 10 99 9.9 13
MW 10 3 9 9 6 9 2 12 2 10 4 66 6.6 6
MW 11 1 11 12 12 11 9 5 9 1 13 84 8.4 12
MW 12 11 3 3 10 3 13 1 13 5 9 71 7.1 9
MW 13 9 13 4 2 13 1 13 1 9 5 70 7.0 8
Chapter 7 : Prioritization of Micro-Watersheds
234
7.10 MORPHOMETRIC ANALYSIS:
The watershed is divided into thirteen micro-watersheds with codes MW 1 to
MW 13.
The various morphometric parameters which have been used in the prioritization
of watershed are calculated and presented in Table 7.7.
Table 7.6 describes the stream order of micro-watershed. Hatmati river has a 6th
order stream covering an area of 1082.62 km2. The micro-watersheds MW-1,
MW-2, MW-9, MW-11 and MW-12 having 4th order streams. The micro-
watersheds MW-3, MW-4, MW-5, MW-6, MW-7, MW-10 and MW-13 having 5th
order streams. The micro-watershed MW-8 and MW-10 having 6th order streams.
The variation in order and size of the sub-watersheds is largely due to physio-
graphic and structural conditions of the region.
Table 7.7 shows the various calculated morphometric parameters which have
been used in the prioritization of micro-watersheds. Table 7.8 shows the 10
parameters, from which compound value (Cp) was calculated for each micro-
watershed. Watershed with lowest Cp value was given rank 1 (MW-2), next lower
value was given rank 2 (MW-3), and so on with highest Cp value was given the
last rank 13 (MW-9).
Fig. 7.24 shows the prioritized micro watersheds map of Hathmati watershed.
Chapter 7 : Prioritization of Micro-Watersheds
235
Fig. 7.24 Prioritized Hathmati Watershed
Chapter 7 : Prioritization of Micro-Watersheds
236
7.11 WATERSHED PRIORITIZATION :
The compound parameter values of all thirteen micro watersheds of Hathmati
watershed are calculated and prioritization rating is shown in Table 7.9. The
watersheds have been broadly classified into three priority zones according to
their compound value (Cp). High (< 7.0), Medium (7.0 - 8.0) and Low (8.0 and
above).
Table.7.9 Final Priority of Micro-Watersheds
Watershed Code No.
Compound Value
(Cp) Rank
Final
Priority
MW 1 6.3 4 High
MW 2 4.6 1 High
MW 3 6.1 2 High
MW 4 6.1 3 High
MW 5 6.5 5 High
MW 6 6.8 7 High
MW 7 8.4 11 Low
MW 8 7.2 10 Medium
MW 9 9.9 13 Low
MW 10 6.6 6 High
MW 11 8.4 12 Low
MW 12 7.1 9 Medium
MW 13 7.0 8 Medium
Watersheds falling under high priority are under very severe erosion susceptibility
zone. Thus need immediate attention to take up mechanical soil conservation
measures gully control structures like check dams and grass waterways to protect
the topsoil loss. While watersheds falling under low priority have very slight
erosion susceptibility zone and may need agronomical measures to check the sheet
and rill erosion. Fig. 7.25 shows prioritized micro watersheds map of Hathmati
watershed.
Chapter 7 : Prioritization of Micro-Watersheds
237
Fig. 7.25 Final Prioritized Hathmati Watershed
Chapter 7 : Prioritization of Micro-Watersheds
238
7.12 SUITABLE SITES FOR CHECK DAMS
The suitability of check dam sites can be confirmed as the site is located on third
order drainage and satisfies the conditions of land use, soil type, and slope as per
IMSD guidelines. The most of the sites in Hathmati watershed were found to be
suitable for check dam but as per ground truth and experience, 7 suitable sites are
proposed to construct the check dam (Fig.7.26). Since it is located in the suitable
land class (Scrub land, River bed), slope (less than 15%) and that serves the
purpose of soil and water conservations and groundwater augmentation. The
proposed check dams could be very useful.
Chapter 7 : Prioritization of Micro-Watersheds
239
Fig. 7.26 Suitable Sites for Check Dams
Chapter 7 : Prioritization of Micro-Watersheds
240
7.13 WATER HARVESTING STRUCTURES DETAILS
7.13.1 Check Dam
These are mostly masonry structures built across ephemeral streams to check the
surface run-off to create surface storage of water in the up-stream side of the
structure even after the monsoon season. (Fig: 7.27 & 7.28).
Fig. 7.27 Check Dam
Fig. 7.28 Check Dam
Chapter 7 : Prioritization of Micro-Watersheds
241
7.13.2 Boulder Bunds
It is a small structure constructed across the first order streams flowing through
mainly crop land area. The purpose of the structure is to prevent soil erosion and
create temporary ponding during the monsoon. It enhances the moisture region in
soil. (Fig 7.29)
Fig. 7.29 Boulder Bunds
7.13.3 Nallah / Gully Plugs
Nallah bunding is suggested at confluence of lower order streams (1st & 2nd) to
check the high velocity surface run-off and allow the water to percolate down.
Mostly these are boulder & earthen structures (Fig 7.30).
Chapter 7 : Prioritization of Micro-Watersheds
242
Fig. 7.30 Nallah/Gully plugs
Fig. 7.31 Concrete Wall
Chapter 7 : Prioritization of Micro-Watersheds
243
7.14 CLOSURE
The chapter presents the methodology for prioritization of the critically affected
watershed of Hathmati river basin of Idar taluka of Sabarkantha district with
erratic rainfall distribution. The generated thematic maps are used in the
evaluation of morphometric parameters such as a bifurcation ratio, drainage
density, and texture ratio, length of the overland flow, stream frequency,
compactness coefficient, circularity ratio, elongation ratio, shape factor and form
factor. Automated demarcation of prioritization of micro-watersheds is done by
using GIS overlaying technique by assigning weight factors to all the identified
features in each thematic map and ranks are assigned to the morphometric
parameters. Three categories of priority viz high, medium, and low are assigned to
all the watersheds.
• • •