24

CHAPTER 3

CHENNAI CITY WATER SUPPLY SYSTEM

3.1 INTRODUCTION

Chennai city, the capital of Tamilnadu state, is located on the coast

of the Bay of Bengal at latitude 13°4” North and Longitude 18°15” East. The

terrain of the city is generally low lying and flat coastal plain known as the

Eastern Coastal Plains, with an average slope of less than 1/1500. Most of the

places are within 4 m to 5 metres above Mean Sea Level (MSL), its highest

point being 60 m. The 368-year-old city is the 31st largest metropolitan area

in the world and fourth largest in India. As of 2000, Chennai city had a

population of 4.2 million, while the total metropolitan population was

6.7 million. The estimated metropolitan population in 2005 is 6.90 million.

The population density of Chennai corporation area is 24,418 per km²

while the overall population density coming under metropolitan area is

5,847 per km².

Two rivers meander through Chennai, the Cooum River in the

central region and the Adyar River in the southern region (Figure 3.1). Both

rivers are heavily polluted with effluents and trash from domestic and

commercial sources. The Adyar, which is much less polluted than the Cooum,

is de-silted and cleaned periodically by the state government. A protected

estuary of the Adyar forms the natural habitat of several species of birds and

animals. The Buckingham Canal, 4 km inland, travels parallel to the coast,

25

linking the two rivers. The Otteri Nullah, an east-west stream runs through

north Chennai and meets the Buckingham Canal at Basin Bridge. Several

lakes of varying size are located on the western fringes of the city. Poondi,

Cholavaram, Red Hills and Chembarampakkam lakes supply Chennai with

potable water. Groundwater sources are mostly brackish.

The geology of Chennai comprises mostly clay, shale and

sandstone. The city is classified into three regions based on geology, sandy

areas, clayey areas and hard-rock areas. Sandy areas are found along the river

banks and the coasts. Clayey regions cover most of the city. Hard rock areas

are Guindy, Velachery, Adambakkam and a part of Saidapet. In sandy areas

rainwater run-off percolates very quickly. In clayey and hard rock areas,

rainwater percolates slowly, but it is held by the soil for a longer time.

3.2 HISTORICAL BACKGROUND

3.2.1 Abstraction of Surface Water

Chennai city map with various water supply reservoirs is shown in

Figure 3.1. Till about 1870, the people of Chennai were dependent on shallow

wells situated in their own houses or on public wells and tanks in the

neighbourhood for their water supply needs. There was no protected water

supply at that time and these sources were not satisfactory. The organised

water supply to Chennai was commenced in 1872, which is the nucleus of the

protected surface water supply system now in existence in Chennai city. The

first major milestone towards protected water supply using filtration and

pumping was achieved during the year 1914. An improved intake tower,

named as Jones tower, was constructed in 1881 at the deepest point in the

Redhills Lake.

26

Figure 3.1 Chennai city map with water supply reservoirs

27

An underground masonry conduit of size 1.52 m x 1.12 m and 11

km long was constructed to convey raw water from Redhills to Kilpauk, with

conveying capacity of raw water at the rate of 104 MLD. Slow sand filters to

purify the water (60 to 70 MLD), four underground pure water storage tanks

(29.50 ML capacity), steam engine driven pumps, an elevated steel overhead

tank (6.75 ML capacity) and 48" diameter steel pumping main from Kilpauk

pumping station to shaft were installed. Subsequently the distribution system

was remodelled and extended to all areas of the city.

Poondi Reservoir (later named as Sathyamoorthy Sagar) was

constructed in 1944 across the Kosathalaiyar River with a capacity of

72.86 Mm3 (2573 Mcft) and placed in service for intercepting and storing

Kosathalaiyar River water. Surplus water flows down the river, which is

again intercepted by Tamaraipakkam anicut and diverted to Cholavaram

Lake. The system was then designed for a supply of 115 LPCD for an

estimated population of 0.66 million expected in 1961. A lined canal known

as Poondi canal was later constructed in 1972 to convey water from Poondi

Reservoir to Cholavaram Lake. Figure 3.2 illustrates the schematic diagram of

surface water supply system for Chennai city.

To meet the immediate needs, various works for conveyance,

treatment and distribution were carried out between 1946 and 1966. Rapid

gravity sand filter treatment facilities with 45 MLD capacity were completed

in 1959. Construction of a second underground masonry conduit (size 1.98 m

x 1.22 m) to convey additional quantity of 146 MLD of raw water from

Redhills to Kilpauk, installations of electrical pumping units at Kilpauk

replacing the 3 steam engine driven pumpsets, 2 additional underground

filtered water tanks of 9 ML capacity each at Kilpauk and expansion and

improvement to distribution system are important works carried out.

28

KESAVARAM AnicutUnlined Canal

Nagari River

Krishna Water

POONDI Reservoir

TAMARAIPAKKAM Anicut

Cooum RiverLink Canal 24.50 Km

Sriperumpudur Tank /Free Catchment Inflow

Bangaru Canal (Unlined)

KORATTUR Anicut

PORUR Lake

CHEMBARAMPAKKAM Reservoir

CHOLAVARAM Reservoir

REDHILLS Reservoir

Kosathalai River

To Chennai CityWater Supply (South) 530 mld

To Chennai CityWater Supply (South) 180 mld +

To Adyar River To Sea

To Chennai CityWater Supply (North)300 + 327 mld (KWW)

To Sea

Poondi-CholavaramDirect Canal(Linedl)15.20 Km.

Upper SupplyCanal (Lined)13.20 Km.

Lower supplyCanal (Unlined)4.20 Km.

FeederCanal10.62 Km

Nandi River

Veeranam Water 235 Km

Created with the Trial Edition of SmartDraw 4.

Figure 3.2 Schematic diagram of surface water supply system for

Chennai city

The construction of a lined channel from Poondi to Tamaraipakkam

for a length of 15 km. to convey water from Poondi to Tamaraipakkam was

completed in 1972 to reduce the transmission loss. The combined capacities

of Cholavaram and Redhills lakes were increased by 19.82 Mm3 (700 Mcft)

by raising the lake bunds. Thus, the combined storage capacity of Poondi,

13.20 Km

29

Cholavaram and Redhills was increased to 178.28 Mm3 (6296 Mcft) against

158.46 Mm3 (5596 Mcft). The irrigation rights of Cholavaram Lake and

Redhills Lake were acquired in 1962 and the entire storage was made

available for the city supply.

Additional 135 MLD capacity rapid sand filter treatment facility

was commissioned in 1969 at Kilpauk. A pre-stressed concrete overhead tank

of 6.8 ML capacity and the 7th underground clear water storage tank with

10 million-litre capacities were constructed at Kilpauk Water Works. The

city distribution system was divided into 12 zones, each zone to feed by a

separate trunk main radially from Kilpauk Water Distribution Station. During

1962, a separate water distribution station was constructed at Anna Poonga to

serve the northern portion of the city and at Thiyagaraya Nagar; the Southern

head works were constructed during 1973 to serve the southern zones. The

existing Kilpauk water distribution station was serving the central portion of

the city.

The Chennai Metropolitan Water Supply and Sewerage Board

(CMWSSB) was constituted as a statutory body in August 1978 for

exclusively attending to the growing need of, and for planned development

and appropriate regulation of water supply and sewerage services in the

Chennai Metropolitan Area with particular reference to the protection of

Public Health and for all matters connected thereto. The CMWSS Board is

vested with the responsibility of planning, construction, operation and

maintenance of water supply and sewerage system in Chennai Metropolitan

Area (CMA). Though its operation is limited to Chennai municipal

corporation area in general, the Board is also extending its services to the

surrounding urban local bodies (with about 7.88 km2. in extension areas and

Manali new town) and has already initiated measures to provide services for

30

the entire metropolitan area. The master plan for the management of water

supply and sewerage for the city, which was prepared in the year 1978, was

revised in the year 1991 and updated in 1997. Improvement and expansion

works are being carried out as per the master plan proposals. The

implementation of master plan proposals has been taken up in stages. At

present, water is distributed to the Chennai city through 16 water distribution

systems. Table 3.1 illustrates the growth profile of the CMWSS Board since

its formation.

Table 3.1 Chennai city water supply, growth profile of CMWSSB

Details 1978 2007

Operational AreaCity170 km2.

City + Surrounding areas(175.18+7.88 km2.)

Population 30 Lakh About 53.75 Lakh

Water Produced (Normal Years) 240 MLD 645 MLD

Area covered with piped supply 80% 99%

Treatment capacity 182 MLD 750 MLD + 530 MLD

Length of water mains 1250 km. 2,887 km.

No. of consumers 1,16,000 4,35,755

Distribution stations 3 Nos. 16 Nos.

3.2.2 Abstraction of Ground Water

Based on the United Nations Development Programme (UNDP)

studies carried out during 1966 to 1969, ground water aquifer was identified

at Tamaraipakkam, Panjetty and Minjur in the Araniar-Kosathalaiyar Basin

(A.K. Basin) located north of Chennai. These three Well fields were

developed for abstracting water at an estimated yield of 125 MLD. Ground

31

water abstracted through bore wells from these well fields was supplied to

Industries in Manali from 1969 by the PWD Ground Water Wing, later on;

this water was partly diverted to city's water supply system from

1981. Chennai city map with various well fields is shown in Figure 3.3.

Figure 3.3 Chennai city map with various well fields

During 1983-86, additional ground water sources were established

based on studies conducted under the UNDP. These include Poondi,

Floodplains and Kannigaiper well fields. The wells in these aquifers were

designed to yield 54 MLD. Along with this, the Thiruvanmiyur coastal

aquifer in the Southern Chennai was also taken over by CMWSSB from the

32

Tamilnadu Water Supply and Drainage Board (TWAD), which supplemented

about 6.80 MLD. The private tanker operators drew water indiscriminately

from this aquifer. Over exploitation of this aquifer has now been prevented by

CMWSSB by enforcement of groundwater regulation act (Madras

Metropolitan Area Groundwater Regulation Act 1987), which provides

licensing for water transport through vehicles.

The continuous extraction of groundwater from the well fields

forced the water table to fall down rapidly. The periodical observation of

electrical conductivity of groundwater shows that the wells nearer the

seacoast in the Minjur area are affected by seawater intrusion. A few

production wells were abandoned due to this seawater intrusion. The sea

water – fresh water interface in the Minjur aquifer which was identified to

exist at 3 km west of the sea shore during the year 1967 was found to have

moved 9 km inland during 1987 (Ramakrishnan 1996), which shows the over

extraction from the aquifer.

All these information on groundwater sources shows the limited

potential and over exploitation of aquifers. The over exploitation of

groundwater sources change the fresh water aquifers into polluted water

aquifers. Once an aquifer is polluted it is very difficult to recover / restore the

aquifer to its original condition. The attempt made by CMWSSB to recover

the seawater-intruded aquifer by means of fresh water injection is in vain due

to several reasons. The Government agencies are trying to augment and

conserve the available water in many ways like exporting water from other

places, desalination of sea water, rain water harvesting etc. All these attempts

have eased water supply shortages of the Chennai city to some extent.

33

3.3 HYDROLOGY OF THE SYSTEM

3.3.1 Climate

Chennai lies on the thermal equator and is also coastal, which

prevents extreme variation in seasonal temperature. For most of the year, the

weather is hot and humid. The hottest part of the year is late May and early

June, with maximum temperatures around 38–42 °C (100–107 °F). The

coolest part of the year is January, with minimum temperatures around

19–20 °C (66–68 °F). The lowest temperature recorded is 15.8 °C (60.40 °F)

and highest temperature in 100 years with Nungambakkam registerings 45 °C

(113 °F) in 30 May 2003. The last time this temperature was recorded on

May 21, 1910, also in Nungambakkam. Table 3.2 shows the weather averages

for Chennai city.

Table 3.2 Weather averages for Chennai city

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec AnnualMaximumTemperature°C

28 31 33 36 38 37 35 34 34 32 29 28 32.90

MinimumTemperature°C

20 21 23 26 27 27 26 26 25 24 22 21 24

Precipitationmm 27.9 33 5.1 12.7 38.1 71.1 121.9 137.2 160 290.5 239.2 152.4 1289.1

MaximumTemperature°F

83 87 91 96 100 99 95 94 93 89 85 83 91.20

MinimumTemperature°F

68 70 74 79 81 81 78 78 77 75 72 70 75.25

Precipitationinch 1.1 1.3 0.2 0.5 1.5 2.8 4.8 5.4 6.3 11.4 9.4 6.0 50.8

34

3.3.2 Rainfall

The average annual rainfall is about 1,300 mm (51 inches). The city

gets most of its seasonal rainfall from the northeast monsoon (from October to

December) and southwest monsoon (from June to September). Percentage of

normal rainfall components for Chennai basin is shown in Figure 3.4.

Table 3.3 shows the average monthly rainfall over Chennai basin.

The average southwest monsoon rainfall of the basin is 422 mm which is

37.30% of the average annual rainfall. The average northeast monsoon

rainfall is 598 mm which is 52.90%. The contribution by the summer and

winter rainfall is insignificant (IWS, 1994). Figure 3.5 illustrates the yearly

rainfall over Chennai basin. Highest annual rainfall recorded is 2,570 mm

(101 inches) in 2005.

NorthEastMansoon52.90%

SouthWestMansoon37.30%

Summer7.00%

Winter2.80%

Figure 3.4 Percentage of normal rainfall components for Chennai basin

35

Table 3.3 Monthly rainfall at Redhills, Cholavaram, Chembarampakkam

and Poondi (in mm)

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total1965 0 11 0 24 0 25 43 186 95 59 422 285 1149

1966 1 0 0 76 5 90 153 239 203 310 492 150 1720

1967 30 0 97 0 52 97 106 223 79 137 122 372 1314

1968 0 0 0 68 0 80 22 14 151 131 140 185 792

1969 0 0 0 0 15 49 117 119 10 656 420 177 1564

1970 0 19 0 5 66 86 495 145 168 171 443 7 1604

1971 14 0 49 26 45 31 156 44 101 497 266 110 1339

1972 34 0 0 0 65 127 51 58 111 506 156 377 1485

1973 0 0 0 0 9 29 73 194 155 261 66 243 1029

1974 8 0 0 0 26 119 112 138 253 109 217 1 983

1975 0 0 0 0 7 48 158 295 231 300 468 1 1508

1976 0 0 0 2 5 109 177 197 9 263 679 7 14491977 4 16 75 27 135 94 476 405 7 12391978 9 17 1 38 145 95 213 98 268 504 13891979 91 30 71 59 133 124 554 78 11391980 12 141 181 18 57 540 172 11211981 16 17 43 38 149 120 135 292 108 89 10061982 2 10 23 81 73 172 79 172 238 9 8591983 18 109 362 329 227 51 308 14041984 18 274 2 34 148 33 232 103 456 117 14171985 51 3 59 161 62 149 115 465 44 11091986 203 61 25 42 51 47 48 238 128 61 9041987 4 20 14 33 33 106 70 178 197 230 8861988 1 17 18 10 103 209 126 70 356 153 10631989 11 9 55 134 22 115 79 343 124 8911990 9 6 7 7 307 54 74 65 171 377 307 50 14341991 8 5 234 75 107 118 284 594 1 14261992 6 29 58 46 86 103 96 305 119 8481993 2 53 50 84 215 116 277 342 206 13451994 2 15 28 17 93 106 58 335 406 222 12821995 84 13 250 9 107 234 200 347 321 1 15661996 59 8 635 34 113 189 394 309 382 21231997 25 10 22 106 57 71 300 250 948 380 21691998 31 5 57 134 147 108 227 401 224 13341999 2 11 7 9 11 45 39 232 216 52 6242000 244 4 40 76 72 162 57 218 96 92 10612001 3 155 18 49 82 80 135 372 242 264 14002002 56 61 42 95 110 159 279 307 20 11292003 5 5 6 26 141 139 103 231 98 56 8102004 30 7 229 50 51 37 191 275 297 5 11712005 0 0 9 101 32 52 84 119 207 590 514 501 2208

Average 21.17 32.00 11.10 22.32 47.00 72.03 103.61 129.05 135.63 253.98 334.22 155.76 1275.44

36

Total Rainfall

1149

1720

1314

792

15641604

13391485

1029983

15081449

12391389

113911211006

859

14041417

1109

904886

1063

891

14341426

848

13451282

1566

21232169

1334

624

1061

1400

1129

810

1171

2208

0

500

1000

1500

2000

2500

1965

1967

1969

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

Year

Rai

nfal

l in

mm

Rainfall CurveLinear (Rainfall Curve)

Figure 3.5 Yearly rainfall over Chennai basin

3.3.3 The Rivers and Reservoirs

Surface water sources such as reservoirs at Poondi, Cholavaram,

Redhills, Chembarampakkam, Veeranam Lake, Rettai Eri, Porur Lake and

Kandaleru Reservoir in Andhra Pradesh under Krishna water supply scheme

are the main sources of water supply for Chennai city and the adjacent urban

areas. The main source of supply for Poondi, Cholavaram, Redhills and

Chembarampakkam reservoir is the river Korataliyar across which Poondi

reservoir is constructed. Tamarapakkam anicut across the river located 30 km

downstream of Poondi serves to divert the flows through the upper supply

channels to Cholavaram tank which in turn is linked to Redhills by the lower

supply channel. From Redhills tank, raw water is conveyed through conduits

to Kilpauk water works where water is treated and supply to north Chennai

city. Through link canal water from Poondi reservoir is diverted to the

Chembarampakkam tank from where water is treated and supplied to south

Chennai city.

37

Poondi reservoir plays an important role since this reservoir

receives the Krishna water from Kandaleru reservoir through Kandaleru

Poondi canal whose capacity is 28.34 m3 / s (1000 cusecs). The inflow into

Poondi reservoir consists of the inflow from Nandi and Nagari rivers,

diversion from Kesavaram anicut, release from Kandaleru reservoir and its

own catchment area. The free catchment of Poondi reservoir is 1968 km2. As

a part of Krishna water supply project, the full reservoir level (FRL) of

Poondi reservoir is raised by 0.60 m above the present FRL 42.7 m. Hence the

gross storage capacity is increased to 98.07 Mm3 (3460 Mcft) from

78.00 Mm3 (2750 Mcft) and the live storage capacity to 97.80 Mm3

(34.50 Mcft) from 77.66 Mm3 (2740 Mcft) from this reservoir, water will be

released to Cholavaram tank, Redhills tank, and Chembarampakkam tank.

The spill flows through Tamarapakkam anicut through the river reach.

The inflow into Cholavaram tank consists of inflow due to the

release from Poondi reservoir, diversion from Tamarapakkam anicut trough

the upper supply channel, and inflow from its own catchment area. The free

catchment area for Cholavaram tank is 28.16 km². The gross storage capacity

of Cholavaram tank is 25.20 Mm3 (889 Mcft) of which the live storage

capacity is 23.55 Mm3 (631 Mcft). From this tank water will be released to

Redhills tank through lower supply channel.

The Redhills tank supplies water through closed conduits to

Kilpauk water works for treatment and supply to North Chennai city. The

inflow into the tank consists of release from Poondi reservoir through the link

canal and then through feeder canal, release from Cholavaram tank and its

inflow from its own catchment area. The free catchment area for Redhills tank

is 37.955 km². Under the proposed system, the full tank level (FTL) of this

tank is raised by 0.60 m above the present FTL, thereby increasing the gross

storage capacity from 80.78 Mm3 (2850 Mcft) to 93.54 Mm3 (3300 Mcft)

38

and the live storage capacity from 7.12 Mm3 (2509 Mcft) to 8387 Mm3

(2959 Mcft).

The Chembarampakkam tank supplies water to the south Chennai

city since 2001. Before that it was supporting irrigation in the surrounding

areas. The inflow into this tank consists of the inflow due to the release from

Poondi reservoir, diversion from Korattur anicut and the inflow from its own

catchment area. The free catchment for Chembarampakkam tank is

77.10 km². The Full tank capacity of this tank is proposed to raise by 0.60 m

above the present FTC of 25.43 m (83.40 ft). Hence the gross as well as the

live storage capacity is to go from 88.44 Mm3 (3120 Mcft) to 103.32 Mm3

(3645 Mcft). The domestic water supply system has always remained

perpetually under the state of water stress and the constraint felt in the limited

storage capacity of the reservoirs to store the flash floods. Several schemes

were put forth from time to time to augment the resources such as Krishna

Water Supply Project (KWSP), New Veeranam Water Supply Project

(NVWSP), Brakish Water based reverse Osmosis Plants and Sea Water

Desalination Plant etc. Ground water from the well fields developed in the

Araniyar - Kortaliar river basin and Southern coastal aquifer is other source of

water supply.

3.4 KRISHNA WATER SUPPLY PROJECT

As per this project, water is drawn from the Srisailam reservoir

when Krishna river is in flood in the month of July-October and January-April

and conveyed to the Somasila reservoir on Pennar river through an open

channel. A reservoir at Kandaleru is linked to the Somasila reservoir by

another canal. From Kandaleru reservoir a canal is run to Poondi reservoir.

This gravity canal flow system backed up by large reservoirs at Srisailam,

Somasila and Kandaleru will enable drawing and holding the flood flows for

irrigation an extent of 2.33 lakh hectares in Andhra Pradesh and a regulated

39

supply of 340 Mm3 (12 TMC) of water per annum at the Tamilnadu border

for Chennai city water supply. During the months from July to October

21.33 m3 / s will be delivered and during the months from January to April

10.93 m3 / s will be delivered. Table 3.4 shows the pattern of receipt of

Krishna water. Andhra Pradesh released Kandaleru water for the first time on

29.9.1996. Further, for the first time, water received under Krishna Water

Supply Project was conveyed to Chembarampakkam Lake during

January 2007.

Table 3.4 Pattern of receipt of Krishna water

Months Total (Mm3)Total after losses

(Mm3)July to October (Mm3) 280 227

January to April (any two months)(Mm3)

140 113

Total 420 (15 TMC) 340 (12 TMC)

Table 3.5 Quantum of water released from Kandaleru and quantity

realized at Tamilnadu border

YearWater released fromKandaleru into K.P.

Canal (in TMC)

Water realized atTamilnadu

border (in TMC)

Percentrealization

1996-1997 0.610 0.076 12.50

1997-1998 4.339 2.290 52.80

1998-1999 4.077 2.810 69.00

1999-2000 3.990 1.830 45.86

2000-2001 17.790 6.688 37.59

2001-2002 1.108 0.400 36.10

2002-2003 9.461 3.262 34.48

40

0

Krishna River

Srisailam Reservoir 8784.00 x106 m3

Pothireddipadu Head Regulator

Banakacherla Regulator

Pennar River

Tamil Nadu / Andhra Pradesh Border

To Chennai City Water supply

To Adyar RiverTo Sea

Velugodu Reservoir 480.00 x106 m3

Brahmmgarimadam Reservoir 502.00 x106 m3

Chennamukkupalli Regulator

Somasila Reservoir 2108.00 x106 m3

Kandaleru Reservoir 1675.00 x106 m3

Poondi Reservoir 98.07 x106 m3

25.275 Km

Cholavaram Reservoir 25.20 x106 m3

Red Hills Reservoir 93.54 x106 m3

ChembarampakkamReservoir 103.32 x106 m3

To Chennai City Water supply

To Chennai City Water supply

Porur Lake0.425 x106 m3

24.50 Km

(15.20 + 13.20) Km

4.20 Km

NOTE: The values with the reservoirnames are the cross storage capacities.

Created with the Trial Edition of SmartDraw 4.

Figure 3.6 Schematic diagram of Krishna water supply project

During 2006-2007, water was received from Kandaleru reservoir in

Andhra Pradesh under Krishna Water Supply Scheme in two spells i.e. 2.869

TMC from 19.08.2006 to 06.11.2006 and 2.315 TMC from 14.12.2006 to

08.02.2007 and the total quantity received is 5.184 TMC. This helped in

41

maintaining the city water supply continuously at the rate of about 645 MLD

even though the inflow in the reservoirs due to the Northeast monsoon was

not appreciable.

Table 3.5 shows the quantum of water released from Kandaleru

dam and quantity realized at Tamilnadu border. During 1991, a proposal for

two new reservoirs, one at Ramancheri and the other at Thirukandalam was

mooted to store excess Krishna Water and flood water but due to land

acquisition problem it had been dropped out. Figure 3.6 shows the schematic

diagram of Krishna Water Supply Project.

3.5 VEERANAM WATER SUPPLY PROJECT

The Veeranam Water Supply Project was implemented as

additional source of water to Chennai city and is aimed at bringing water from

Veeranam Lake situated about 235 km south of Chennai in Cuddalore district.

This lake receives water from Cauvery River system through Kollidam,

Lower Anicut and Vadavar Canal besides rainwater from its own catchment

area. The capacity of the lake is 41.48 Mm3 (1465 Mcft). The lake water is

treated at Vadakuthu Water Treatment Plant by pumping raw water at a

distance of 20 km from Sethiathope to Vadakuthu through 1775 mm diameter

mild steel pipe. The treated water is then pumped at a distance of 8 Km to

Break Pressure Tank at Kadampuliyur through 1750 mm diameter mild steel

pipe and from there the water is conveyed to a distance of about 200 Km

through the mild steel pipe of 1875 mm and 1500 mm diameter by gravity to

Porur Water Distribution Station near Chennai. From Porur Water

Distribution Station, water is pumped to a distance of 1.2 km and distributed

to Chennai city through Trunk mains and Water Distribution Stations.

Veeranam lake particulars are given in Table 3.6.

42

Table 3.6 Veeranam Lake particulars

Veeranam LakeLocation Cuddalore district, Tamilnadu, South India

Coordinates 11°20 10 N 79°32 40 E Coordinates

Lake type Reservoir, intermittent

Catchment area 25 km2

Maximum length 11.2 km

Maximum width 4 km

Veeranam water supply project would bring about 180 MLD to

Chennai city. This is about one third requirement of water in Chennai city per

day. The full supply of 180 MLD of water to Chennai city through the New

Veeranam Project commenced on 13.10.2004 has greatly reduced dependency

on distant sources. During the years of deficit rainfall, water in the Veeranam

Lake may not be sufficient. Hence, it was decided to implement a project

called the New Veeranam Extension Project to draw sub surface water in

Kollidam riverbed and pump the same to Sethiathope and then to Chennai

through the New Veeranam Project infrastructure. The proposed scheme is to

draw 150 MLD sub surface water from the Kollidam river by constructing 6

Nos. of collector wells between mileages 39/3 and 59/0 in the Kollidam river.

This proposal envisages that the water from the Collector Wells will be

pumped to a sump and then conveyed by the pipeline to Sethiathope raw

water pumping station constructed under the Chennai water supply

augmentation project-I (New Veeranam Project) for onward transmission to

Chennai city through the pumping and pipeline arrangements of Chennai

water supply augmentation project – I. Figure 3.7 illustrates the Veeranam

lake and pipeline route map.

43

Figure 3.7 Map illustrates the Veeranam lake and pipeline route of

Veeranam water supply project

44

3.6 SEA WATER DESALINATION PLANT

Keeping in view the chronic problem of water scarcity in

Chennai and adjoining areas due to frequent failure of the monsoons,

it had been decided to set up a Sea Water Desalination Plant as a viable

source for all seasons for supply of potable water to the residents of Chennai

and adjoining areas. Accordingly CMWSS Board has proposed to construct a

Sea Water Desalination Plant of 100 MLD / 200 MLD capacity at Minjur on

Design, Build, Own, Operate and Transfer (DBOOT) basis at the northern

outskirts of Chennai city near Minjur.

3.7 DATA BASE OF THE SYSTEM

Future water considers data as a key issue in any water

supply system and many of our endeavors focus on collecting

data required for further analysis. At the same time decision makers /

managers see data as a starting point and they have broad experiences

in transforming data to information and use this information to explore

options for the future. Future water needs expertise in data-mining, where

data from different global domain sources, satellites, and local sources are

used or convert to the required information. Information, from investigations,

is used for allocating water among multiple users and resolving water

disputes. The salient features of Chennai city’s existing water supply system

are given in Table 3.7.

45

Table 3.7 Salient features of Chennai city’s existing water supply

reservoirs

Name of Reservoir

FullTankLevel(m)

Storage atsill level(Mm3)

Waterspread areaat sill level

(Mm2)

Storageat F.T.L(Mm3)

Waterspread area

at F.T.L(Mm2)

Poondi 42.06 0.28 0.12 98.07 10.79Cholavaram 19.66 0.00 0.67 25.20 6.56Red Hills 14.69 9.67 2.09 93.54 21.55Chembarambakkam 26.04 0.00 0.00 103.32 25.57

Total 11.54 2.88 320.13 64.41

The Salient features of Chennai city’s combined reservoir are given

in Table 3.8. Figure 3.8 represents water spread area and storage details of

Chennai city’s combined reservoir. The ground water supply to the Chennai

city varies between 2 Mm3 to 5 Mm3 per month.

Table 3.8 Salient features of Chennai city’s combined reservoir

Water Spread Areain Mm2

Total Storage inMm3

Live Storage inMm3 Remarks

0.0000 0.002.8800 11.54 0.00 Dead Storage

10.3700 51.54 40.0018.4180 91.54 80.0026.4660 131.54 120.0034.5140 171.54 160.0042.5620 211.54 200.0050.6100 251.54 240.0058.6580 291.54 280.0062.6820 311.54 300.0064.4100 320.13 308.59 Full Tank Level

46

0.0011.54

51.54

91.54

131.54

171.54

211.54

251.54

291.54311.54 320.13

0

50

100

150

200

250

300

350

0.00 2.89 10.37 18.42 26.47 34.51 42.56 50.61 58.66 62.68 64.41

Water spread area in Mm2

Stor

age

in M

m3

Figure 3.8 Chennai city’s combined reservoir’s water spread area and

storage curve

To compute evaporation loss, water spread area corresponding to

combined reservoir’s storage and evaporation rate corresponding to a

particular month are used. For example, computation of evaporation loss as

shown in Equation 3.1 for the month January is achieved as follows:

Evaporation loss = [(Water spread area for the available beginning storage in

the reservoir) * (Average monthly evaporation rate for

the month of January)] (3.1)

Salient features of Chennai city water supply canals are given in

Table 3.9. Figure 3.9 illustrates the average monthly evaporation rate from the

Chennai city’s water bodies.

47

Table 3.9 Salient features of Chennai city’s water supply canals

DescriptionLength Capacity Remarks

km Miles Cumecs CusecsPoondi-cholavaram directchannel

35.20 9.50 2.83 100 Lined

Upper supply channel 13.20 8.25 34.00 1200 Unlined

Lower supply channel 4.20 2.63 25.50 900 Unlined

Redhills-kilpauk conduits

I 11.00 6.88 1.22 43 Masonry

II 11.00 6.88 1.22 43 Masonry

III 11.00 6.88 1.22 43 Masonry

0.1166

0.1361

0.1752

0.1935

0.2189

0.19170.1779

0.16550.1506

0.1345

0.1086 0.1094

0.00

0.05

0.10

0.15

0.20

0.25

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMonth

Evap

orat

ion

rate

in m

/ m

onth

Evaporation rate in m / month

Figure 3.9 Average monthly evaporation rate from the Chennai city’s

water bodies

48

3.8 PRESENT WATER SUPPLY SYSTEM

The present water supply system consists of surface storage at

Poondi, Cholavaram, Redhills and Chembarampakkam. The main source of

supply for this reservoir is the river Korataliyar across which Poondi reservoir

is constructed. Tamarapakkam anicut across the river located 30 km

downstream of Poondi serves to divert the flows through the upper supply

channels to Cholavaram tank, which in turn is linked to Redhills by the lower

supply channel. From Redhills tank raw water is conveyed through conduits

to Kilpauk water works, where water is treated and supplied to North Chennai

city. Through a link canal, water from Poondi reservoir is diverted to the

Chembarampakkam tank from where water is treated and supplied to south

Chennai city.

As per the Krishna Water Supply Project (KWSP), a regulated

supply of 340 Mm3 of water per annum is to be released at the Tamilnadu

border for Chennai city.

The Veeranam Water Supply Project, which was commissioned in

October 2004, provided a lifeline for the Chennai city. This project brings

about 180 MLD of water through steel tube to Chennai; this is about one third

requirement of water in Chennai per day.

Chennai Metro Water Supply and Sewerage Board (CMWSSB) has

developed 7 numbers of well fields namely, 1. Poondi, 2. Tamaraipakkam,

3. Flood Plains, 4. Kannigaiper, 5. Panjetty, 6. Minjur, and 7. Southern

Coastal Aquifer, in which about 74 numbers of deep bore wells are in

existence. Apart from this, CMWSSB has executed water purchase agreement

49

with private agricultural owners. From both the sources about 100 MLD water

is extracted for augmenting Industrial and City water supply.

Unfortunately, till date, there is no specific operation policy for the

Chennai city water supply system except flood control and flood warning

guidelines. In this situation, comparison can be made possible by deriving an

optimal operation policy from the past release records and based on the

derived rule. The past releases are made mainly based on the experience of

the Engineers. The release data for the combined reservoir is collected from

the Chennai Metro Water Supply and Sewerage Board (CMWSSB) for a

period of twenty-three years, January 1985 to December 2007. With the

available data, the monthly release made from the combined reservoir is

plotted against the respective beginning storage for each month. The plots are

shown in Figures 3.10 to 3.21.

0

2

4

6

8

10

12

14

16

8 40 4 2 4 8 53 53 62 6 4 72 82 9 6 10 4 10 9 132 14 6 152 175 178 19 1 19 6 199 2 4 4 26 8Beginning storage in January in M m3

Rel

ease

in Ja

nuar

y in

Mm

3

Figure 3.10 Operation practiced from 1985 to 2007 in January

50

0

2

4

6

8

10

12

14

6 28 3 5 4 2 44 53 57 6 6 67 68 9 6 97 10 5 12 1 14 9 155 16 2 16 4 175 18 0 184 18 8 2 52Beginning storage in February in Mm3

Rel

ease

in F

ebru

ary

in M

m3

Figure 3.11 Operation practiced from 1985 to 2007 in February

0

2

4

6

8

10

12

14

16

4 20 3 2 3 8 45 53 54 58 61 6 8 8 5 86 9 2 106 13 6 146 14 7 14 9 156 158 170 19 2 2 30Beginning storage in March in Mm3

Rel

ease

in M

arch

in M

m3

Figure 3.12 Operation practiced from 1985 to 2007 in March

51

0

2

4

6

8

10

12

14

16

6 13 2 5 3 3 3 5 4 7 48 4 9 51 59 72 83 9 0 9 0 12 1 124 12 5 13 1 132 13 3 134 14 7 151Beginning storage in April in Mm3

Rele

ase

in A

pril

in M

m3

Figure 3.13 Operation practiced from 1985 to 2007 in April

0

2

4

6

8

10

12

14

16

4 9 2 0 3 0 33 3 8 38 4 1 4 2 53 6 1 66 78 92 10 5 106 10 7 10 9 111 111 119 12 4 13 6Beginning storage in May in M m3

Rel

ease

in M

ay in

Mm

3

Figure 3.14 Operation practiced from 1985 to 2007 in May

52

0

2

4

6

8

10

12

14

16

18

4 4 16 2 0 29 3 0 33 3 4 4 1 44 4 9 54 6 1 85 8 6 8 7 87 9 1 103 10 3 113 12 3 12 4Beginning storage in June in Mm3

Rel

ease

in Ju

ne in

Mm

3

Figure 3.15 Operation practiced from 1985 to 2007 in June

0

2

4

6

8

10

12

14

16

18

0 3 12 14 21 2 3 25 2 8 31 34 4 5 49 6 7 70 71 73 86 8 7 89 10 8 113 119 13 4Beginning storage in July in Mm3

Rel

ease

in Ju

ly in

Mm

3

Figure 3.16 Operation practiced from 1985 to 2007 in July

53

0

2

4

6

8

10

12

14

16

18

0 1 9 10 18 18 20 2 2 2 4 2 5 3 9 40 55 58 58 6 2 73 76 76 8 6 8 9 9 7 10 4Beginning storage in August in Mm3

Rel

ease

in A

ugus

t in

Mm

3

Figure 3.17 Operation practiced from 1985 to 2007 in August

0

2

4

6

8

10

12

14

0 0 6 8 13 15 15 16 18 2 0 3 1 3 3 46 50 59 6 0 6 4 6 6 6 6 82 9 7 10 3 112Beginning storage in September in Mm3

Rel

ease

in S

epte

mbe

r in

Mm

3

Figure 3.18 Operation practiced from 1985 to 2007 in September

54

0

2

4

6

8

10

12

14

0 0 5 7 9 11 15 17 19 2 3 28 2 9 39 4 2 51 55 56 71 72 9 1 115 13 4 2 03Beginning storage in October in Mm3

Rel

ease

in O

ctob

er in

Mm

3

Figure 3.19 Operation practiced from 1985 to 2007 in October

0

2

4

6

8

10

12

14

3 6 7 9 11 2 0 26 3 3 3 5 3 8 43 4 8 55 58 69 71 8 0 12 3 134 13 5 178 20 2 2 32Beginning storage in November in Mm3

Rel

ease

in N

ovem

ber i

n M

m3

Figure 3.20 Operation practiced from 1985 to 2007 in November

55

0

2

4

6

8

10

12

14

16

8 25 3 6 38 4 5 4 8 50 59 60 6 6 94 111 118 14 5 149 150 180 18 4 185 19 4 2 21 23 6 2 37Beginning storage in November in Mm3

Rel

ease

in N

ovem

ber i

n M

m3

Figure 3.21 Operation practiced from 1985 to 2007 in December

0

20

40

60

80

100

120

140

160

180

12.1

8

37.7

7

40.5

6

68.3

8

68.4

5

72.2

4

97.6

0

101.

95

111.

61

115.

90

119.

81

130.

26

130.

57

149.

26

153.

15

160.

93

193.

43

213.

88

322.

85

326.

63

419.

02

511.

41

555.

82

Yearly Inflow in Mm3

Yea

rly A

ctua

l Rel

ease

in M

m3

Figure 3.22 Inflow Vs Release – Operation practiced from 1985 to 2007

Beginning storage in December in Mm3

56

It is a general understanding that the release will be proportional to

storage available and it cannot be low release with high storage or vice versa.

The Figure 3.10 to Figure 3.21 shows that in few months the releases are

topsy survey, because with higher storage, comparatively less water was

released, or with lower storage comparatively more water was released. For

example, in Figure 3.10 in January 1987 the beginning storage is 42.28 Mm3

and the release was 6.87 Mm3, whereas in January 1988 the beginning storage

of 63.99 Mm3 but the release made was only 3.84 Mm3.

Similarly from Figure 3.22 it has been observed that in 1999 the

total inflow is 101.95 Mm3 and the total release was 147.02 Mm3 whereas in

1985 the total inflow is 322.85 Mm3 and the total release made was only

86.20 Mm3. These facts justify the necessity of a well-framed operating policy

and guidelines for equitable distribution of available surface water to

Chennai city.