chapter 5 formulation of water management strategies...
TRANSCRIPT
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CHAPTER 5
FORMULATION OF WATER MANAGEMENT
STRATEGIES AND ANALYSIS
5.1 INTRODUCTION
Water demand management-controlling and influencing the amount
of water used by consumers in areas where there is a scarcity of water
resources-raises issues for communities, water providers and regulators for
which there is rarely a simple solution. It has become an important element in
integrated policies of water resources development. Multilateral and bilateral
funding agencies involved in the water sector recognize the need for better
understanding of the implications of introducing water demand management
measures and in particular, the impact on the livelihoods of the poor. Thus the
water demand management can be broadly viewed as an interactive approach
that addresses competing community demands placed on a region's water
resources so as to meet defined water quantity and quality objectives.
The principle infrastructure components required to satisfy water
demand management include
• drinkable water supply
• sewage collection, treatment and disposal
• stormwater collection and disposal
• recycled water collection, storage, treatment and re-use.
The various management options that can be adopted include
increasing the urban water use efficiency, conjunctive management of surface
water and groundwater, recycling the municipal waste water, increasing the
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agricultural water use efficiency, desalination, increasing the conveyance
efficiency etc.
5.2 FUTURE WATER REQUIREMENTS FOR CMA
Increasing urban population and urban needs would put more
pressure in future for water. But the current supply position from the surface
sources is nowhere near the need. The solutions to water crisis are quite
closely associated with integrated view of water governance-which
encompasses issues such as long-term perspective and planning and a broad
based partnership and dialogue among all key stakeholders. The present
project strives to work towards contributing to this goal.
The census data for the years 1981, 1991 and 2001 were collected
and the Chennai Metropolitan Area’s future population is forecasted using
geometrical increase method. It is found to be 137.5 lakhs for the year 2025.
Figure 5.1 shows the growth of population in the Chennai Metropolitan Area
for a period of 2001 to 2025. The increase of water demand for the respective
years are showed in Figure 5.2
0
20
40
60
80
100
120
140
160
2001 2005 2010 2015 2025
YEAR
PO
PU
LA
TIO
N (
LA
KH
S)
Populat ion in Lakhs
Figure 5.1 Population Growth in CMA
85
0
200
400
600
800
1000
1200
1400
2001 2005 2010 2015 2025
YEAR
DE
MA
ND
(M
LD
)
Demand in MLD
Figure 5.2 Water Demand in CMA
In CMA, for the year 2025, for the population of 137.5 lakhs, the
total requirement of water will be of the order of 1292 MLD. If the existing
system of water supply is continued, the demand for the growing population
in the Chennai Metropolitan Area cannot be met satisfactorily. Apart from
that, there will be head to tail losses and pressure variations in the distribution
pipelines, difficulty in transporting water from distant sources and
administrative difficulties. To overcome the above problems, the Chennai
Metropolitan Area can be classified into different sectors. Water can be drawn
from the nearby sources, treated and distributed in the sector itself in an
effective manner.
5.3 SECTORIAL CLASSIFICATION OF CHENNAI
METROPOLITAN AREA
For the present study, the Chennai Metropolitan Area is divided into
4 interconnected and independent sectors. They are north sector, central
sector, south sector and west sector. An autonomous body has to be set up in
each sector that manages all the activities including the acquisition, storage,
treatment, quality maintenance and distribution of water for that sector. Thus
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each sector can be made self sufficient to meet its own water demand. This
will help in the equitable distribution of water throughout the sectors.
5.4 AREA CATEGORIZATION IN EACH SECTOR
The categorization of the study area is listed below.
5.4.1 North Sector
The north sector is primarily an industrial area having an areal
extent of 355.94 sq.km. The places that comes under the north sector are
Minjur, Athipattu, Padianallur, Kattivakkam, Ponneri, Polichur,
Chinnasekkadu, Puzhal, Naravarikuppam, Manali, Madhavaram, Tiruvottiyur,
Washermanpet, Fort, Tondiarpet, Royapuram, Harbour, Perambur (Kolathur,
Vyasarpadi), Sembium and Park Town.
5.4.2 Central Sector
Central sector is the commercial heart of the city and the downtown
area. Egmore, Chindadripet, Nungambakkam, Metha Nagar, Mylapore,
Chepauk, Triplicane, Purasawalkam (Villivakkam, Ayanavaram, Aminjikarai,
Kellys), T.Nagar, Teynampet, Ambattur, Avadi, Poonamallee,
Thiruverkadu,Thirunindravur, Nerkundram, Maduravoyal, Anna Nagar,
Mugappair, Thousand Lights and Thirumazhisai are the places coming under
the central sector. The central sector occupies an area of 362.66 sq.km.
5.4.3 South Sector
South sector, a previously predominantly residential area is fast
turning into a commercial area, hosting a large number of IT and financial
companies. Tambaram, Perungalathur, Chitlapakkam, Sembakkam,
Peerkankaranai, Moovarasampettai, Vandalur, Madambakkam,
Meenambakkam, Tirusulam, Pallavaram, Pammal, Anakaputhur,
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Thiruneermalai, Kundrathur, Oggaiyamduraipakkam, Perungudi, Taramani,
Velachery, Thiruvanmiyur, Adayar, Kottivakkam, Palavakkam, Neelankarai,
Karapakkam, Sholinganallur, Kelambakkam, Injambakkam, Alandur,
Madipakkam, Puzhithivakkam, Jalladiampet and Pallikaranai are included in
the south sector having an areal extend of 316.10 sq.km.
5.4.4 West Sector
The west sector is similar to the south sector having mixed land
uses, with inter- mixture of urban and non-urban uses. The west sector also
adjoins the Chennai Municipal Corporation limits and comprises residential
areas that are fastly developing. In addition, it has got several large industrial
and business establishments and has high metropolitan level of health and
higher educational institutions. This sector comprises of middle income, low
income and poor income residents.
The places included in this sector are Guindy, Porur, Ramapuram,
Manapakkam, Nandampakkam, Sikkarayapuram, Valasaravakkam,
Karambakkam, Mangadu, Ekkattuthangal, Kodambakkam, M.G.R. Nagar,
K.K.Nagar, Vadapalani, Nesapakkam and Virugambakkam occupying an area
of 137.30 sq.km. The sectorial classification of Chennai Metropolitan Area is
shown in the Figure 5.3.
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Figure 5.3 Sectorial Classification of CMA
SCALE 1:50000
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5.5 WATER MANAGEMENT STRATEGIES FOR NORTH
SECTOR
The north sector is primarily an industrial area. The Araniar and
Kosasthalaiyar rivers originate in Andhra Pradesh and join the sea near
Chennai. The river basins covers an area of about 1000 sq.km and is situated
about 30 km north to Chennai city. Groundwater is the major source of water
supply in this sector. There are plenty of well fields available in this area. The
major source of the north sector is the Araniar Kosasthalaiyar Basin. This
basin contains enormous amount of water that itself will be sufficient to cater
the water requirements of this sector. During the monsoon period, huge
quantity of water drains to the sea. This enormous source has to be properly
managed by adopting strategies separately for both pre monsoon and post
monsoon periods.
From the population data, the future population for the north sector
is forecasted for the years 2005, 2010, 2015 and 2025 and the demand is
assessed using the TWAD Board norms. The forecasted population and water
demand for the north sector is shown in Table 5.1.
Table 5.1 Population and Demand for North Sector
Year Population
(Lakhs)
Demand
(MLD)
2001 17 177
2005 19 191
2010 20 208
2015 23 229
2025 28 278
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For the year 2025, the population is forecasted as 28 lakhs and the
water demand is 278 MLD. The management strategies to improve the water
supply for the north sector are as follows.
5.5.1 Construction of Reservoir in Araniar Kosasthalaiyar Basin
Generally flood occurs during north east monsoon when there is
heavy rainfall coupled with cyclonic storms formed in the Bay of Bengal
which inundates the basins of Araniar, Kosasthalaiyar and its tributaries.
During monsoon large quantity of water is draining through the Araniar and
Kosasthalaiyar Rivers to Bay of Bengal.
The combined average surplus of the Araniar River at
A.N. Kuppam and Lakshmipuram anicuts was 143 Mm3 (390 MLD) during
the year 1976-2000. It is inferred that at 50% dependability, the surplus
amount of water is 50 Mm3 (136 MLD) and at 75% dependability the surplus
is 28 Mm3 (76 MLD). The average surplus of Kosasthalaiyar River at Vallur
anicut was 202.5 Mm3 (552 MLD) for the period of 1976-2000 and the
surplus amount of water at 50% dependability is 23 Mm3 (62 MLD) and there
is no surplus water at 75% dependability (Institute for Water Studies).
The surplus at 75% dependability of the A-K basin, nearly 28 Mm3
(76 MLD), can be utilized by saving it properly. This can be achieved by
constructing a reservoir of 36.63 Mm3 (100 MLD) near the Araniar
Kosasthalaiyar basin that will improve the water potential of this sector. The
reservoir also serves the adjacent areas by recharging the groundwater thereby
maintaining the ecological balance. Also check dams has to be constructed
across the Araniar and Kosasthalaiyar Rivers to recharge the groundwater.
Already proposals for reservoirs namely Ramanjeri and Thirukandalam across
river Kosasthalaiyar have been made by the government department. Due to
peoples agitation in that area it was given up.
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5.5.2 Stormwater Runoff
In the present study, due importance is given to develop a
stormwater management plan for each sector, that addresses the existing
problems of wastage of water and provides guidance for conservation for the
future. In CMA, the rainwater drained as runoff can be managed and
consumed appropriately, to meet the water scarcity of the growing population.
The north sector has an areal extent of 355.94 sq.km where the
water bodies occupy 45.5 sq.km. Considering the average annual rainfall for
the north sector as 1081 mm, the runoff accounts to 50.35 Mm3 (137 MLD)
for an areal extent of 310.44 sq.km. Measures can be adopted to the store this
runoff generated during the monsoon and can be supplied during the non
monsoon period. The storage can be done by collecting the stormwater
through stormwater drains and storing it in storage structures constructed at
vacant lands of Manali and Palavoyal (Landuse Map and Toposheets) each
with a storage capacity of 21.97 Mm3 (60 MLD). A detailed study has to be
conducted for implementing the recommendation given above.
In addition to the storage structures, the tanks and lakes can also be
used to store the excess runoff. In this sector, apart from Cholavarm and
Redhills Lake that supplies water to Chennai city, Erattai eri having a storage
capacity of 0.98 Mm3 (2.67 MLD) (CMWSSB) can be deepened and
converted to a recharge structure that improves the groundwater status of the
sector.
5.5.3 Additional Well Fields
The Araniar-Kosasthalaiyar basin has a groundwater potential of
690.48 Mm3 (1885 MLD) (Source: Chennai Metro Water Supply and
Sewarage Board) and hence usage of the aquifers to augment the water supply
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to Chennai are huge. Presently about 37.36 Mm3 (102 MLD) is drawn from
the A-K well fields to the Kilpauk water works. This shows that there is
653.12 Mm3 (1783 MLD) of water available in this basin. Additional well
fields has to be drilled to extract the required groundwater during drought.
Self yield should be worked out for each area and accordingly the pumping of
water from the well fields should be limited so as to prevent execess
withdrawal of groundwater. This will also prevent the seawater intrusion.
This can be implemented in an efficient manner by conducting appropriate
hydrogeological investigations.
5.5.4 Water Treatment Plant at Ponneri
The water potential in the north sector is so high that if provisions
are made to store and treat the water in this sector itself, the difficulties in
transporting water can be eliminated. Considering the factors like the
accessibility from various sources, availability of vacant land and easiness to
distribute water, Ponneri is chosen for constructing the water treatment plant.
The provision of a water treatment plant in this sector will also serve the
increasing demand due to the industrial development in the northern parts of
Chennai Metropolitan Area.
A water treatment plant of capacity 300 MLD is recommended to be
constructed at Ponneri against a total water requirement of 278 MLD in the
year 2025. The surplus water of 28 Mm3 (76 MLD) stored in the proposed
reservoir in the Araniar Kosasthalaiyar Basin, the stored surface runoff of
43.95 Mm3 (120 MLD) and wellfields providing 30 Mm
3 (82 MLD) will be
able to meet the requirement. This water can be brought to the water treatment
plant at Ponneri, where it is treated and distributed to various parts of the
north sector. This will improve the existing infrastructure of water supply
system in the north sector.
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5.5.5 Overall Management
For the north sector, 278 MLD of water is required for a forecasted
population of 2774311 during the year 2025. The management strategies
recommended to meet the demand satisfactorily in the north sector includes
usage of surplus water by constructing a reservoir in Araniar-Kosasthalaiyar
Basin, storing the runoff water in storage structures as well as in tanks and
lakes, drilling additional well fields and constructing a water treatment plant
at Ponneri.
During monsoon periods, the groundwater will increase and the
people will mostly depend on their own individual wells. As the groundwater
usage is more, the quantity of water that has to be supplied by the water
supply boards will be less. The surface water can be stored for non monsoon
period. Even if the extraction of groundwater is more, it will be recharged by
the monsoon showers as well as by the check dams constructed across the
river courses.
During non monsoon period, the water availability in the individual
wells will be less. So the water requirements have to be met by the water
supply boards. The conjunctive use of surface water and groundwater can be
adopted for this period. The surplus water stored during monsoon and the
stored stormwater runoff can be supplied in addition to the groundwater from
the well fields. A detailed study has to be done to decide on the frequency of
water supply that has to be adopted for the monsoon and non monsoon
periods. This can be achieved by analyzing the present water supply strategy
adopted by the water supply boards.
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5.6 WATER MANAGEMENT STRATEGIES FOR CENTRAL
SECTOR
Central sector is the commercial heart of the city. At present, the
water supply for the Chennai city and the near by areas is given from the
Kilpauk water works. The water to the Kilpauk water works is drawn from
various surface water sources such as Redhills, Poondi and Cholavaram and
the groundwater is extracted from the well fields such as Poondi,
Tamaraipakkam, Panjetty, Minjur, Kannigaiper, Southern coastal aquifers and
Porur infiltration wells. Also the external sources of water like Telugu Ganga
water and New Veeranam water contributes to Kilpauk water works.
To solve the water crisis, by sectorial classification, some of the
places which comes under the Kilpauk water works were excluded and some
new areas were included to form the central sector. Those places that were
excluded are Perambur, Washermanpet, Vyasarpadi, Patel Nagar, Harbour,
Tiruvottiyur, Royapuram, Tondiarpet, Manali and George Town in the north,
Adayar, Thiruvanmiyur and Velachery in the south, Kodambakkam,
M.G.R.Nagar, K.K. Nagar, Nesappakam, Vadapalani, Virugambakkam,
Saligramam, West Mambalam, Saidapet, Ashok Nagar, Ekkaduthanal,
Guindy and Saint Thomas Mount in the west. These places were added
respectively to the other sectors.
From the population data, the future population for the central sector
is forecasted for the years 2005, 2010, 2015 and 2025 and the demand is
assessed. The forecasted population and water demand for the central sector
are shown in Table 5.2.
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Table 5.2 Population and Demand for Central Sector
Year Population
(Lakhs)
Demand
(MLD)
2001 31 325
2005 34 357
2010 39 397
2015 45 457
2025 60 595
In the central sector, for the year 2025, the population is forecasted
as 60 lakhs and the water demand is 595 MLD. The management measures
that are recommended for the central sector are as follows.
5.6.1 Kilpauk Water Works
According to the sectorial classification, the water from Kilpauk
water works is to be used for the central sector alone. The present capacity of
Kilpauk water works is 327 MLD. According to 2001 census the city’s
population is 43 lakhs and the water demand is 477 MLD. As per the sectorial
classification, population to be served by the Kilpauk water works for the year
2001 is revised to 31 lakhs and the corresponding demand is 325 MLD.
Hence the stress on the Kilpauk water works to serve more population is
reduced.
By analyzing the present water supply carried out by the metro
water supply board, a quantity of 78 Mm3 (213 MLD) of the surface water is
supplied from the Poondi, Cholavaram and Redhills. The groundwater from
the well fields accounts to 37.36 Mm3 (102 MLD).
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5.6.2 Stormwater Runoff
The central sector has an areal extent of 362.66 sq.km where the
water bodies occupy 34.5 sq.km. Considering the average annual rainfall for
the central sector as 1108 mm, the runoff accounts to 54.57 Mm3 (149 MLD)
for an areal extent of 328.16 sq.km. In the central sector, 88.23 sq.km. is
occupied by the Chennai city.
The stormwater runoff that is generated outside the Chennai city
accounts to 39.90 Mm3 (109 MLD) that can be conserved for central sector.
This can be achieved by designing a proper stormwater drain network and
diverting it to the storage structures that can be constructed in the vacant lands
available outside the city limits of this sector. A detailed study has to be
conducted for the design of stomwater network. Kovilpadugai near Redhills
lake (Landuse Map and Toposheets), that has a larger extent of vacant land, is
identified for constructing a storage structure having a capacity of 36.63 Mm3
(100 MLD).
In addition, a number of lakes and tanks are available in the western
side of the central sector. The surface water sources that comes in the central
sector are Ambattur Tank, Korattur Lake, Maduravoyal Lake,
Ayyanambakkam Lake, Nadukuthagai Lake, Sundara Cholapuram Lake,
Koladi Lake, Paleripattu Lake and Arapeth Eri with a combined approximate
storage of 25.18 Mm3 (68.74 MLD). In addition to the storage structures, the
lakes and tanks of the central sector can be deepened and used as recharge
structures to store the excess runoff from the adjacent areas. A provision can
be made to draw about 10.98 Mm3 (30 MLD) of water from the tanks and
lakes.
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The tanks and lakes are in the grip of encroachment by city
dwellers on its banks. It is the only means that can conserve the ecological
balance of Chennai. At present, all these tanks and lakes are in the stage of
vanishing. The encroachment on the approach channels have to be removed
and the proper measures have to be adopted for free flowing of water during
monsoon. Government have to initiate actions to clear the encroachments and
rehabilitate them. They should also enact laws to prevent further
encroachments. The lakes and tanks should also be standardized to bring it
back to its original condition. The system of tanks have to be rejunuvated so
that the surplus of the upstream tank will directly flow by gravity to the
downstream tanks. This will also improve the of groundwater status of this
sector.
5.6.3 Overall Management
In this sector, both the surface and groundwater comprises
315 MLD. Apart from these, nearly 100 MLD of water comes from the
stormwater runoff can be stored in recharge structures. About 30 MLD can be
taken from the tanks and lakes. To meet out the gap, a system to abstract,
harness and supply the groundwater from the A-K basin well fields that has
an availability of 1783 MLD can be planned. This can be achieved by drilling
additional well fields in the Araniar-Kosasthalaiyar Basin by conducting
appropriate hydrogeological investigations. Therefore, additional water of
80 MLD can be tapped from newly proposed wellfields in Araniar
Kosasthalayar Basin so as to meet the demand satisfactorily.
This shows that the water from the existing internal surface and
groundwater sources are enough to cater the needs of the central sector. The
external sources like Telugu Ganga and Veeranam water are recommended to
be diverted to cater the needs of other sectors.
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For the central sector, 595 MLD of water is required for a predicted
population of 5993775 for the year 2025. The management strategies thus
recommended to meet the demand satisfactorily includes improved
distribution of water by reallocating areas to be served by Kilpauk water
works, storing the runoff water in storage structures as well as in tanks and
lakes and drilling additional well fields in A-K Basin. A detailed study has to
be conducted for each of the above management strategies recommended to
implement it in action.
During drought period, if the internal sources were not able to meet
the requirements, suitable arrangements should be made to distribute the
external water sources to the sectors. To meet out this requirement, a partial
amount of the Veeranam water and Telugu Ganga water has to be taken to the
central sector through the existing pipelines.
5.7 WATER MANAGEMENT STRATEGIES FOR SOUTH
SECTOR
The south sector has mixed land uses, with inter-mixture of urban
and non-urban uses and is yet to become fully urbanized. These areas have
developed as overspill of city development. This sector also have a large
number of small and medium manufacturing and business enterprises,
specialty restaurants and recreation places. The water requirement for the
institutional and the industrial needs are more compared to the domestic needs
of this sector. This can be met with proper planning and allocation of the
water resources, for which identification of new water sources is essential.
The places under this sector namely Kottivakkam, Palavakkam,
Neelangarai and Injambakkam are located along the coast and bisected by the
East Coast Road, a major highway leading to the southern coastal areas of the
state. It is bound on the west by a manmade canal (viz. The Buckingham
canal once used for navigation), which follows low-lying flats having
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connection with the sea at a few points. This area gets its water supply from
the southern coastal aquifers, individual wells and public wells.
From the population data, the future population for the south sector
is forecasted for the years 2005, 2010, 2015 and 2025 and the demand is
assessed. The forecasted population and water demand for the south sector are
shown in Table 5.3.
Table 5.3 Population and Demand for South Sector
Year Population
(Lakhs)
Demand
(MLD)
2001 10 89
2005 12 105
2010 15 126
2015 19 159
2025 32 258
The population forecasted for the south sector for 2025 is 32 lakhs
and the corresponding water demand is 258 MLD. In order to meet the
demand of the south sector, the following suggestions are given.
5.7.1 Water from River Palar
River Palar is the major water source 60 km south of Chennai city
that supplies water to few areas of south sector. It mainly caters water during
the monsoon, as flash floods are common during the northeast monsoon.
Presently, a number of infiltration wells sunk in the river at Palayaseevaram,
Vengudi, Kullambakam etc. together supplement 9.16 Mm3 (25 MLD) of
water to the peri urban areas like Alandur, Pallavaram, Tambaram, Pammal
and Chitlapakkam.
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To increase the subsurface water availability in the River Palar
region, sand mining has to be reduced. Also constructing check dams across
the river in the downstream of Palayaseevaram will help to recharge the
groundwater in the surrounding regions, thereby the infiltration wells gets
boosted up and this water can be used to satisfy the growing demand in the
south sector.
5.7.2 Water from Veeranam Project
Apart from this, water from the Veeranam Project can be taken to
the south sector. The amount of water that is supplied through this project to
Chennai is 66 Mm3 (180 MLD). As of now, the Veeranam water enters the
Chennai Metropolitan Area at Tambaram and it is transported to Porur Lake.
Instead the water can be stored by deepening and desilting the Thiruneermalai
tank near Tambaram. As a result, the transportation difficulties for a longer
distance can be minimized and the water can be effectively used by the
consumers of the south sector.
5.7.3 Stormwater Runoff
The south sector has an areal extent of 316.10 sq.km where the
water bodies occupy 12.2 sq.km. Considering the average annual rainfall of
this sector as 1198 mm, the runoff accounts to 54.65 Mm3 (150 MLD) for an
areal exent of 303.90 sq.km. This runoff that is generated can be stored to
augment the water supply of this sector. This can be achieved by collecting
the stormwater by laying stormwater drains and storing it in structures
constructed at vacant lands of Oggiyamduraipakkam, Nemilicheri and
Pallikaranai (Landuse Map and Toposheets) each with a storage capacity of
14.65 Mm3 (40 MLD).
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The surface water sources for the south sector of Chennai
Metropolitan Area has to be improved. The details of the water sources which
are available and presently not in use in the south sector are Peerkankaranai
Lake, Tambaram Puduthangal Lake, Tambaram Periya Eri, Kadaperi Lake,
Pallavaram Lake, Nemilicheri Lake, Pallikaranai Anai Eri, Kovilambakkam
Periya Eri, Perungudi Lake, Pallikaranai Narayanapuram Lake and Velachery
Lake with an approximate storage of 2.43 Mm3 (6.6 MLD) (CMWSSB). In
addition to the storage structures, measures can be taken to deepen the tanks
and lakes. The excess runoff from the adjacent areas of the tanks and lakes
can be diverted to it that will improve the groundwater status of this sector.
5.7.4 Water Treatment Plants
To meet the basic needs of the people in the south sector and to
provide an improved water supply, nearly 258 MLD is required. With all the
surface sources, groundwater sources and the external water sources, water
can be supplied to the south sector by constructing two water treatment plants
each of capacity 100 MLD. One water treatment plant can be placed at
Oggiyamduraipakkam and another at Tambaram where provisions can be
made to collect, store, treat and distribute water to cater the needs of the south
sector.
The water treatment plant constructed at Oggiyamduraipakkam will
serve water to the south east coastal areas like Oggiyamduraipakkam,
Sholinganallur, Kelambakkam, Kottivakkam, Palavakkam, Neelangarai,
Injambakkam, Perungudi, Adayar, Velachery and Pallikaranai. The treatment
plant at Tambaram can provide water to the areas like Tambaram, Tambaram
Sanatoruim, Perungalathur, Chitlapakkam, Sembakkam, Peerkankaranai,
Moovarasampettai, Madampakkam, Vandalur, Chrompet, Pallavaram,
Pammal, Anakaputtur, Kundrathur, Thiruneermalai, Trisulam,
Meenambakkam, Alandur, Puzhithivakkam, Madipakkam and Jalladiampet.
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5.7.5 Overall Management
For the south sector, 258 MLD of water is required for a predicted
population of 3248235 for the year 2025. The management strategies
recommended to meet the demand satisfactorily includes water from River
Palar, New Veeranam water, stormwater runoff and construction of water
treatment plants at Oggiyamduraipakkam and Tambaram. A detailed study
has to be conducted for each of the above management strategies
recommended to implement it in action.
During normal and above normal rainfall years, people will be
depending more on their own individual wells. In the non-monsoon season,
the water from the external sources can be supplied as per the management
strategies recommended for the south sector. And in the monsoon periods, the
demand of the south sector can be met mostly with the available internal
surface and groundwater sources along with a considerable amount of
Veeranam water. At times of excess rainfall the Veeranam water can be
stopped temporarily as it lies within Tamil Nadu.
During drought, suitable arrangements have to be made to supply a
part of the Veeranam water to both south sector and central sector. A part of
Veeranam water can be taken to the Porur Lake through the existing pipelines
and can be used for central sector.
5.8 WATER MANAGEMENT STRATEGIES FOR WEST
SECTOR
The west sector is similar to the south sector having mixed land
uses, with inter- mixture of urban and non-urban uses. The west sector also
adjoins the Chennai Municipal Corporation limits and comprises residential
areas which are fastly developing. In addition, it has got several large
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industrial and business establishments and has high metropolitan level of
health and higher educational institutions.
At present the public water supply systems are operated by the local
bodies. The systems were installed by the Tamil Nadu Water Supply and
Drainage Board under the State Rural/Urban Water Supply Programme. The
system consists of local wells, from which water is pumped to overhead tanks
and distributed through pipelines. The consumers are supplied either through
individual house connections or street taps. Most of the poor draw their water
from street taps. A large number of better off population, commercial,
institutional and industrial establishments which are not covered by the above
system draw their water requirements from insitu open or bore wells.
From the population data, the future population for the west sector is
forecasted for the years 2005, 2010, 2015 and 2025 and the demand is
assessed. The forecasted population and water demand for the west sector are
shown in Table 5.4.
Table 5.4 Population and Demand for West Sector
Year Population
(Lakhs)
Demand
(MLD)
2001 8 77
2005 9 86
2010 10 98
2015 12 115
2025 17 161
In the west sector, for the year 2025, the population is forecasted as
17 lakhs and the water demand is 161 MLD. In order to meet the demand of
the west sector, the following suggestions are given.
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5.8.1 Telugu Ganga Project
Telugu Ganga Project has been recently implemented, primarily to
meet the pressing need of water supply to Chennai Metropolitan Area. By
mutual agreement, 336 Mm3 (12 TMC) of water has to be delivered to Poondi
reservoir in Tamil Nadu. Presently only 84 Mm3 (3TMC) of water is given
that augments the water supply to Chennai.
At present, the entire amount of water coming from this project is
distributed to the Chennai city alone. But for the present study, the entire
amount of water received in Poondi reservoir by Telugu Ganga Project can be
directly diverted to the Chembarambakkam Lake and stored. This water can
be taken to the Porur Lake through the Thanthi channel and can be treated at
the Porur water treatment plant from which the water can be supplied to the
west sector alone. Policy decisions has to be taken by the concerned
authorities.
5.8.2 Water from Chembarambakkam Lake
The Chembarambakkam Lake is one of the major lakes in Tamil
Nadu having a water spread area of 165 sq.km and a storage capacity of
103.2 Mm3 (282 MLD). This lake lies in the west sector of Chennai
Metropolitan Area. The water from the Telugu Ganga Project and the local
catchment area can be stored in Chembarambakkam Lake, which can also be
diverted through the Thanthi channel as an additional source for the Porur
Lake to cater the needs of the west sector. The quantity of water that can be
stored and diverted can be determined through modelling and this is beyond
the scope of this study.
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5.8.3 Stormwater Runoff
The west sector has an areal extent of 137.30 sq.km where the water
bodies occupy 14.06 sq.km. Considering the average annual rainfall of the
west sector as 1264 mm, the runoff accounts to 23.36 Mm3 (64 MLD) for an
areal extent of 123.24 sq.km. This excess water can be stored to augment the
water supply to this sector that can be achieved by collecting the stormwater
through stormwater drains and diverting it to a storage structure constructed at
vacant lands of Irungattukottai near Chembarambakkam Lake (Landuse Map
and Toposheets) with a storage capacity of 21.97 Mm3
(60 MLD). The rest of
the water can be diveted to the tanks and lakes.
The present capacity of the Porur Lake is 1.83 Mm3 (5 MLD). The
Porur Lake can be deepened to increase its capacity. This will aid in storing
more water during monsoon and will aslo help in storing the surplus water
from Chembarambakkam Lake instead of draining to River Adyar. In addition
to all these measures, there are a number of infiltration wells in the
surroundings of Porur. Provisions can be made to improve the existing
groundwater level by saving the stormwater runoff of that sector.
5.8.4 Water Treatment Plant at Porur
For the present study, a water treament plant of capacity 180 MLD
can be installed at Porur for the west sector. The groundwater potential in this
area is high that if provisions are made to store this water in this sector itself,
the difficulties in transporting the water from the water bodies to the Kilpauk
water treatment plant can be eliminated. The provision of a water treatment
plant will also help in meeting the increasing demand. Thus introducing a
water distribution station at Porur will improve the existing infrastructure of
water supply system in the west sector.
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5.8.5 Overall Management
For the west sector, 161 MLD of water is required for a predicted
population of 1733637 for the year 2025. The management strategies
recommended to meet the demand satisfactorily includes water from Telugu
Ganga Project, Chembarambakkam Lake, storage of stormwater runoff and
construction of water treatment plant at Porur. A detailed study has to be
conducted for each of the above management strategies recommended to
implement it.
Thus by adopting the sectorial classification of water distribution
system, the present water supply for Chennai Metropolitan Area can be
managed effectively and successfully. A rough estimate is prepared for the
management strategies of each sector by analyzing the works and proposals of
the concerned departments as well as conducting survey with the officials.
The cost estimate is presented in the Appendix. The summary of the features
of the four sectors are given in the Table 5.5.
Table 5. 5 Features of identified sectors of Chennai Metropolitan Area
Description Sectors
North Central South West
Areal extent (sq.km) 355.94 362.66 316.10 137.30
Average annual rainfall (mm) 1081 1108 1198 1264
Projected population for the year
2025 (Lakhs) 28 60 32 17
Forecasted water demand for the
year 2025 (MLD) 278 595 258 161
Proposed surface storage (Mm3) 80.57 36.63 14.65 21.97
Existing treatment plant
capacity (MLD) - 327 - -
Proposed treatment plant
capacity (MLD) 300 - 200 180
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The figures provided in all the four sectors are initial values and are
to be arrived at through detailed technical analysis.
5.9 ADDITIONAL WATER MANAGEMENT STRATEGIES
Apart from the management strategies adopted sector wise, some
overall measures can be taken for the water management in Chennai
Metropolitan Area. They are river conservation measures, wastewater reuse,
desalination and creating awareness to the public about the importance of
water conservation and management.
5.9.1 Conservation of Water Bodies in CMA
Most of the lakes in the Chennai Metropolitan Area are polluted
with sewage and garbage and are environmentally degraded. The suburban
areas of Chennai had numerous lakes and now the water bodies in
Adambakkam, Ambattur, Chitlapakkam, Nanganallur, Perungudi,
Tiruneermalai, Velachery, Villivakkam and Vyasarpadi have been encroached
upon to accommodate the growing population. Also, the remaining portion of
the lakes are used as dumping ground for industrial and municipal wastes thus
making it unfit for any level of human consumption. This further deteriorates
the quality of groundwater and pollutes the aquifer in the neighbourhood,
causing water-borne diseases.
Chennai being a water scarce city, the eco-restoration of these lakes
will go a long way in augmenting the water requirements of the city and also
will be recharging the dwindling groundwater table. During the monsoon
season the residential areas around these lake areas get inundated due to
blockages in the natural drains to the lakes. In order to alleviate these
problems, a comprehensive eco-restoration plan for the lakes should be
formulated.
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To check this visible human encroachment, there is a need to
monitor the water bodies. Haphazard human habitation often makes it
difficult to delineate the original extent of the lake. A comprehensive water
management plan has to be formulated not only to revive the vanishing water
bodies but also to put an end to poor urban planning leading to unsustainable
growth in the long run. Such a proactive approach will help when the
monsoon fails or becomes erratic.
It is necessary to catalogue and restore all the tanks in and around
the city to capture the runoff. Presently all the temple tanks are polluted with
weeds. They need improvement and restoration. They are to be cleaned from
slush and silt. The inlets to the temple tanks have to be widened and cleaned.
The steps to the tanks have to be made of cement mortar to prevent seepage
on sides. This improves storage. Cut stone steps and retaining walls on all the
four sides is to be provided to prevent deposition of silt due to erosion. PVC
pipes should be provided for draining rainwater into the tanks. Stoneware
pipes have to be laid at the compound walls to drain street water into temple
tanks during monsoon. The tanks should be protected all around by fences.
The encroachment problems around the tanks are to be prevented through
public participation and NGO action. Private organizations and firms can
carry out the rehabilitation of the temple tanks. Further maintenance and
operation of these tanks must be handed over to the public.
5.9.2 Wastewater Reuse
Drinking water is a limited resource. Rapid growth and development
in Chennai Metropolitan Area has put extreme demands on the sources of
high quality water. In order to increase the access to water, the following
three elements are especially important.
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1. Development of new water sources
2. Prevention of water resource degradation
3. Improvement in efficiency of water consumption.
Wastewater reuse contributes to all of above three elements.
Wastewater reuse can serve as an alternative source of water and can reduce
the pollution load to water environment by less discharged wastewater. The
wastewater reuse in agriculture and industry can enable more water to be used
in an efficient manner. By the reuse of wastewater, the amount of nutrients
discharged to our rivers will get considerably reduced, thereby protecting the
environment. Also the reuse water often cost less to the consumers than the
drinking water.
Some of the areas in the Chennai Metropolitan Area where the
recycled water can be used are irrigation of lawns, golf courses, cemeteries,
parks, school grounds, industrial and commercial landscapes, highway
medians and to recharge the groundwater. The recycled water can also be
used in industry and manufacturing processes such as cooling water and
boiler blow down, at construction sites, in decorative ponds and fountains,
vehicle washing, toilet flushing, in sprinkler systems located at the
commercial or industrial buildings and fire protection. The main goal of the
reuse of the wastewater in the Chennai Metropolitan Area is to improve the
health of humans, increased access to water supply and to improve the
sanitation.
5.9.2.1 Reuse of Household Wastewater
The wastewater generated in households can be classified as grey
water and black water. The grey water is defined as untreated household
wastewater that has not come in contact with toilet waste and includes
wastewater from bathtubs, showers, washbasins, washing machines and
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laundry tubs, but does not include wastewater from kitchen sinks or
dishwashers or laundry water from washing of materials soiled with human
excreta. The various sources of grey water and black water are shown in the
Figure 5.4.
Figure 5.4 Sources of Household Wastewater
In the prevailing sewerage system of Chennai, the grey water is not
reused as it is discharged into sewer system along with the black water. This
grey water can be utilized if it is separated from black water, thereby reducing
the fresh water consumption. It can be reused without pre-treatment for
agricultural or landscape irrigation in household scale or in larger scale. This
can be further increased to 60 percent by reusing wastewater after in situ
treatment. Some recommendations for reuse of the household wastewater are
as follows:
• For recharging the groundwater in Chennai Metropolitan
Area, the grey water obtained from the households can be
Toilet Dish washer Cloth washer
Bath shower Miscellaneous
Grey water Black water
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diverted towards a specially prepared soil bed, in which semi-
aquatic plants can be grown. If the water is to be recycled, the
bottom of the bed should be made permeable to allow
percolation.
• From each multi-storied complex, a network of two different
pipes can be laid to separate the black water and grey water at
the initial stage itself. Such projects require moderate capital
investment as well as minimal maintenance. An example for
such a complex network is at Tambaram, an 80-flat apartment
constructed by Alacrity foundation, where the system is now
three years old. Here, the quality of drinking water has
remained stable and a dry bore well has begun yielding. The
system operates on the principle of gravity with no related
problems of chemicals, smell or mosquito breeding. Hence if
this measure can be implemented in a micro level in
individual houses, it will lead to efficient reuse of wastewater
generated from the households and ultimately improve the
water access and the sanitation of the Chennai Metropolitan
Area.
• Grey water use greatly extends the useful life and capacity of
septic systems. For municipal treatment systems, decreased
wastewater flow means higher treatment effectiveness and
lower costs.
• In Chennai Metropolitan Area, the places like Anna Nagar,
Mogappair, Korattur, Padi, Thandarai, Palleripattu, Puzhal,
Villivoyal, Ponneri and Thirumullaivoyal have clayey soil
which has a slow water percolation. The grey water can be
recycled by constructing oxidation ponds in these areas, which
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can serve as a partial or complete substitute instead of having
a very costly over-engineered system.
• The nutrients present in the household wastewater are going
waste when it is let to the waterways. These nutrients can be
used in an effective manner if nutrients can be collected and
used as landfills to maintain the fertility of the land.
Apart from the reuse of household wastewater, the reuse of effluent
released from various industries in Chennai Metropolitan Area is also possible
in a wide range of categories from agricultural to potable purposes. The
sewerage effluent, in most cases the secondary effluent, is recycled with or
without treatment having specific water quality standards to meet the various
needs.
5.9.2.2 Effluent Reuse for Urban Applications
In urban cities like the Chennai Metropolitan Area, the recycling
system of effluent plays a great role for controlling water consumption and
reducing its pollutant load on the environment. There are big potentials for
introducing wastewater reuse in the city with high rate of water usage and
discharging wastewater everyday. Most of the water that are used for urban
activities need not have the quality as high as that of drinking water. In most
cases, the secondly treated domestic wastewater followed by sand filtration
treatment and disinfections can be used for non-potable purposes in urban
water reuse i.e., applications for toilet flushing in business or commercial
building, car washing, garden watering, park or other open space planting,
fire-fighting and so on. The schematic representation of reclaimed water use
in an urban area is shown in Figure 5.5.
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Figure 5.5 Schematic Diagram of Reclaimed Water Use
5.9.2.3 Effluent Reuse for Environmental Water Enhancement
Effluent reuse of the Chennai Metropolitan Area can also be applied
actively for the environmental enhancement such as augmentation of natural
and artificial stream, fountain and ponds in parks. Proper quality guideline has
to be considered on the assumption that human contact with the reused water
and sufficient disinfection has to be carried out by chlorination or UV
radiation. In addition to the hygienic aspect, the removal of the nutrients
which includes nitrogen or phosphorus should also be kept in view since it
may cause algal blooming which will deteriorate the quality and appearance
of the stream.
5.9.2.4 Effluent Reuse for Industry
The secondary effluent produced from the industries of the various
sectors in the Chennai Metropolitan Area can also be reused with or without
treatment and disinfection to meet intended purposes such as cooling
processes and boiler blow down. In addition to reduction in water
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consumption and pollution load to the environment, industrial water reuse in
Chennai Metropolitan Area can have the following specific benefits like
potential reduction in production costs from recovery of raw materials in the
wastewater, less permitting and administrative burden from the reduction in
wastewater toxicity as well as volume and heat recovery and reduced impacts
from high temperature effluent to the ecosystem.
5.9.2.5 Effluent Reuse for Groundwater Recharge
In Chennai Metropolitan Area, due to the rapid growth of
population, over exploitation of the groundwater is taking place without
knowing its consequences. The problems that may arise are seawater intrusion
in the coastal zones mainly in the north and south sectors, desertification and
degradation of land which occurs mainly due to reduction in the natural
potential of the land and depletion in surface and groundwater sources, drying
up of wetlands, reduction in pumping capacity and land subsidence.
In order to safeguard the groundwater table, percolation and
withdrawal of water from the aquifers should be properly balanced. Also there
is a frequent failure of monsoon. The groundwater potential is getting
degraded day by day and the water table has to be maintained. Effluent from
the industries can be reused for the recharge of groundwater. Compared to
conventional surface water storage, aquifer recharge has many advantages
such as negligible evaporation, little contamination by animals, no algae
blooming and less cost as construction of pipelines is not required. For other
benefits, it protects groundwater from saltwater intrusion by barrier formation
in coastal regions and control or prevents land subsidence.
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5.9.2.6 Potable Reuse of Effluent
Growing populations and increasing constraints on the development
of new water sources have spurred a variety of measures to conserve and
reuse water over the last two or three decades. Potable reuse of wastewater is
made possible by improved water treatment technologies and water analysis
techniques to detect the presence of microbial and chemical contaminants.
Even though the potable reuse of effluent is not generally recommended,
under worst conditions of water scarcity this option can be considered.
5.9.3 Desalination
Along with recommendations of water distribution by sectorial
division of each area, rehabilitation of tanks and rivers, construction of check
dams across the rivers, wastewater reuse etc., it is necessary to look for new
technologies which are viable and indigenous to match the increasing needs.
It has to be looked forward to solve the problem of water scarcity.
Desalination is such an attempt in this way. It is still in incipient stage
keeping cost involved. Technology has to march forward to bridge the gap
between the cost and demand and some recommendations are suggested
below:
• The yield of fresh water for every 100 litres of sea water
would be 1 to 1.5 litres. The water however would be so pure
that it would actually have to be ‘polluted’ with raw water to
make it potable and fit for consumption. As a means to
overcome the high cost involved in the desalinated water,
provisions can be arranged to supply this water to meet the
commercial water demands instead of providing it for the
domestic purposes. Desalinated water can be supplied to those
commercial places like high class hotels, hospitals and IT
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industries that can bear the high cost, so that the stress caused
by them to the normal water supply can be reduced to a
considerable level.
• By implementing desalination plants in many areas of the
CMA, the process will not only provide the people with fresh
water but also generates edible salt or caustic soda, that are
marketable that concludes desalination will no longer be an
expensive technology to get fresh water from sea water. The
market prices of these products eventually nullify the cost of
production of fresh water and tilt the scale towards profit.
• At present the drinking water requirement of the Chennai
Metropolitan Area is more which will further increase when
the commercial and industrial water needs are taken into
consideration. The implementation of the desalination plants
at several parts of the coastal areas will contribute
significantly to meet the Chennai Metropolitan Area’s water
requirement beneficially.
• Desalination technique cannot be used as a direct alternative
source but in a very high water crisis condition it can
considered as one of the various management strategies to
meet out the requirements.
5.9.4 Awareness to Society for Conservation of Water
For any management strategy to be successful, the cooperation of
public is vital. By providing awareness to the society about the water crisis,
importance of saving even a single drop of water and the efficient usage of
water, the water managers can bring remarkable changes in the water sector.
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Some of the measures that can be adopted by the pubic to save water indoor
and outdoor are recommended as follows
• People by themselves can adopt some protective measures to
reduce the leakage in pumps and pipelines at home. Leak
detection and maintenance in pumps and pipelines should be
done regularly. Each and every household should be verified
for water leakage, because many homes may have hidden
water leaks. The water meter should be read before and after a
two-hour period when no water is being used. If the meter
does not show exactly the same readings, it indicates there
exist leakage in pipelines. Report all significant water losses
to the local authorities.
• The flushing of the toilet often must be reduced. And care
should be taken that the toilet flush handle does not frequently
sticks in the flush position. If such a condition exists the water
will run constantly, then it has to be replaced immediately.
Minimum amount of water should be used for bath. The water
should not be wasted by opening the tap continuously, while
brushing the teeth, shaving or washing the face. Operate
automatic clothes washers only when they are fully loaded or
properly set the water level for the size of load required.
• The water must be used economically while gardening. The
lawns should be watered during early morning hours, when
temperature and wind speed are low. This will reduce the loss
due to evaporation.
• Micro and drip irrigation are examples of water-efficient
methods of irrigation. The sprinklers can be positioned so that
the water directly sprinkles on the lawns and shrubs, and not
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on the paved areas. The sprinkler systems and timing devices
must be checked regularly to make sure that they are in the
proper operating condition.
• Over fertilization of the lawns should be avoided. The
application of fertilizers will increase the need for water.
Apply fertilizers which contain slow release, water-insoluble
forms of nitrogen. Mulching can be practiced to retain
moisture in the soil. Mulching control weeds that otherwise
may compete with plants for water.
• All the water-conservation, water shortage rules and
restrictions must be strictly followed in all the places. All the
employers have to be encouraged to promote water
conservation at their workplace. It is also suggested that water
conservation can be put in the employee orientation manual
and training programs.
• The business that can promote water conservation must be
patronized. All the school system and local government
should be encouraged in developing and promoting a water
conservation ethic among children and adults. Also the public
has to support efforts and programs to create a concern for
water conservation among tourists and visitors to the state and
encourage the public to be part of a water conscious
community. The conservation of water can be promoted by
community newsletters and bulletin boards to ensure the
importance of water.
• The various Non-Governmental Organizations that work for
improving Chennai’s water condition are Akash Ganga,
Exnora, SUSTAIN etc. These organizations can contribute
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markedly in implementing the sectorial management of water
distribution by working with the respective institutions and by
creating public awareness on the subject of the precious water.
5.9.5 General Recommendations
• In the peri urban areas of CMA where development is
extensive, area around the proposed buildings should be left
unpaved. The storm water will infiltrate through the unpaved
areas and will recharge the groundwater. Similarly space can
be left around the open wells also. In order to implement this,
the government has to pass an act that should be strictly
followed by the public. Also the government can give
incentives to those people who leave more unpaved areas
around their built-up place than the regulations specified by
the government.
• The city can be planned in such a way that separate pipe lines
can be laid to carry sewage and sullage water from house
holds. This helps in the economical treatment of sullage water.
The sewage from the individual houses should be connected to
a public sewerage system and treated in a common oxidation
pond. This will reduce the groundwater contamination that
may arise after years due to leakage of individual septic tanks.
The sewage water after treatment can be supplied to meet the
secondary uses like cooling of Air Conditioning ducts, ice
plants, boilers, etc. Also the biogas generated from solid waste
treatment can be used effectively for household purposes.
• In flats, the usage of water can be estimated as a whole and
pipes can be laid to cater the needs of all the houses within it.
This can be achieved by increasing the diameter of the
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existing pipes. To satisfy the needs of institutions, IT
industries, star hotels, high commercial buildings, the amount
of water supplied can be metered and can be charged
separately.
• The city star hotels needs between 1.2 lakh litres to 3 lakh
litres a day. They are depending on private tankers at the time
of acute water shortage. Hence sewage conversion and sea
water desalination can be adopted. The reclaimed water can be
sold at the same charge as that of the metro water.
• In the coastal areas new law has to be framed to prevent the
over extraction of groundwater. The government should insist
the public not to drill bore wells beyond a considerable depth.
This prevents the salt-water intrusion and safeguards CMA’s
coastal ecosystem.