Module 2 Conservation of Natural Resources (21CV654)

CONSERVATION OF NATURAL RESOURCES (21CV654)

MODULE -2
WATER: Global water resources, Indian water resources, Resources system planning. Water
use sectors- domestic, industrial, agriculture. Water deficit and water surplus basins in India,
equitable distribution, Inter-basin water transfers, Interlinking of rivers – Himalayan component,
peninsular component, issues involved. Ground water, its potential in India, conjunctive use,
recharge of ground water. Contamination of ground water, sea water ingress, problems and
solutions.

Continuation…

Inter-Basin Water Transfers (IBWTs):

 Inter-basin transfer or transbasin diversion is the moving of water from a watershed
with a surplus to a watershed suffering from a shortage.
OR
 The deportation of water from one river basin to another is known as inter basin transfer
of the water.
 The water is transferred primarily to alleviate water scarcity in the recipient basin and
travels long distances via complex pipeline and canal systems. Other reasons include
recipient basin hydropower generation and the navigation route expansion.
 Inter-basin transfers are often considered a controversial practice, as the environmental
and socio-economic consequences for the donor basin can be high, and difficult to predict.
Therefore, it is strictly regulated in many areas and completely prohibited in others.
 USA, Australia and India were the first countries to implement the inter basin transfer
techniques in the 19th century. Australia, India and the United States, feeding large cities
such as Denver and Los Angeles.
 The Inter basin water transfer helps to prevent the formation of deltas along the coast line
and migration of people from drought affected regions.
 In order to decrease water resource problems, such as water shortages and uneven
distribution, more than 160 water transfer projects have been carried out worldwide until
2015.

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The International Hydrological Program (IHP) has introduced five criteria for justifying or
rejecting IBWT projects.
These criteria are:
1. The area of delivery must face a substantial deficit.
2. The future development of the area of origin must not be substantially constrained by
water scarcity.
3. A comprehensive environmental impact assessment must indicate that the project will
not substantially degrade environmental quality within the area of origin or area of
delivery.
4. A comprehensive assessment of socio-cultural impacts must indicate a reasonable
degree of certainty that it will not cause substantial socio-cultural disruption in the area
of origin or area of water delivery.
5. The net benefits from the transfer must be shared equitably between the area of origin
and the area of water delivery.
Therefore, any IBWT project should be evaluated based on these five criteria.
Existing Inter Basin Water Transfer Projects in India and Other Countries:
Examples of Inter basin water transfer in India
1. Periyar – Vaigai project (Kerala state 1985)
2. Kurnool – Cuddapah Canal (Andhra Pradesh 1863-1870)
3. Parambikulam – Aliyar project (1962-82)
4. Telugu – Ganga project
5. Beas – Sutlej Link (1983)
6. Indira Gandhi Nahar project (Rajasthan canal, 1958)
7. Sarada – ahayak Project (1960)
8. Ramganga – Ganga Link (1978)
9. Tungabhadra – Pennar project
10. Mahi project
11. Tehri Multipurpose project
In other countries
Many large-scale water transfer schemes have been planned and implemented in other countries
also.

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1. South-north water transfer project, China

2. Tagus-Segura transfer project, Spain
3. Lesotho highlands water projects, South Africa
4. California’s State Water Project, United States
Need for Inter Basin water transfers (IBWT):
Inter Basin Water Transfers is necessarily required to overcome the water scarcity situations in
the regions/basins. These are needed to enhance water utility and reduce water wastage of water
surplus areas in the following manner:
1. Large variation in rainfall and available water resources in space and time
2. Diversion of water from water surplus basins to water deficit basins/regions
3. Use of the surplus water which is otherwise flowing into the sea unutilized
4. To mitigate likely adverse impact of climate change, short term and long term
Merits and Demerits of Inter Basin Water Transfer Merits:
Merits
1. Possible to utilize the water resources uniformly and economically to yield significant
output.
2. Enhancement in Irrigation potential and power generation
3. Provides ample surface water to meet the growing needs of Domestic and Industries.
4. Scopes for Inland Navigation which reduces stress on existing communication system.
5. It minimizes the intensity of drought and floods.
6. It helps to increase per capita income.
7. Reduces the exploitation of ground water as surface water is made available in abundant.
8. Huge employment generation
9. Development of fisheries
10. Salinity control
11. Recreation facility
12. Infrastructural development
13. Socio economic development
14. Considerable improvement in ground water potential
15. Control in migration
16. Conversion of barren land into culturable land

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17. Reduction in formation of further deltas in coastal zones.

18. Minimization of the relief expenditure towards floods and droughts.
Demerits
1. Large area liable for submersion due to construction of reservoirs and canals
2. Adverse effects over ecological system
3. Difficult to solve Interstate or International water disputes
4. Legal problem in sharing the water
5. Cost of the project and recurring expenditure for maintenance are high
6. Water pollution in conveyance
7. Loss of water in conveyance through the canals
8. Land acquisition and rehabilitation problems
9. Requires afforestation to compensate for loss in green
10. It is a long term project which may cause large variation in estimation
11. Serving for high altitude areas needs pumping of water which requires huge power and
maintenance.
12. Needs huge debate at micro level and macro level on the issue to convince the public.
13. Problems of soil erosion and sedimentation
14. In undulated zones it may require to construct large number of cross drainage works.

Interlinking of Rivers (ILR) – Himalayan Component, Peninsular

Component, Issues Involved:
Interlinking of Rivers (ILR):
 Interlinking of Rivers is a way to transfer excess water from the regions which receive a
lot of rainfall to the areas that are drought prone.
 India is a subcontinent traversed by 12 chief river systems. The lion’s share of this surface
water is utilized for agriculture and the rest is divided among domestic and industrial
purposes.
 India being a monsoon dependent country, receives a sizeable amount of surface water from
its annual rainfall.
 The major share of this rainfall tends to runoff into the rivers. If and when this rain water is
not stored properly, the conditions of draught or flood prevail.

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 Hence for a uniform distribution of the existing waters, interlinked basins have been
deployed in some parts of India connecting the peninsular and Himalayan rivers. Similarly,
in China, a multi infrastructure project, under the name of South.
 The initial plan to interlink India’s rivers came in 1858 from a British irrigation engineer,
Sir Arthur Thomas Cotton.
 This idea was revisited in 1960 by the then Minister of State for Energy and Irrigation, KL
Rao, who proposed to link rivers Ganga and Cauvery.
 In 1977 Captain Dastur proposed Garland of canal around the Himalayan, Central and
Peninsular India.
 The interlinking of river (ILR) was introduced in 1982; it was actively taken up during Atal
Bihari Vajpayee’s tenure as Prime Minister during 1999–2004.
 In 2002, the Supreme Court asked the government to finalize a plan for interlinking rivers
by 2003 and execute it by 2016.
 In response to this order, the Government of India appointed a Task Force and scientists,
engineers, ecologists, biologists and policy makers started to deliberate over the technical,
economic and eco-friendly feasibility of this gigantic project.
 Since 2015, Indian Government has implemented river interlinking projects in several
segments such as the Godavari-Krishna river interlining in Andhra Pradesh and the Ken-
Betwa rivers interlink in Madhya Pradesh.
 These projects are built with aims that it will enhance annual per capita water availability for
increasing population of the country.
 The Godavari-Krishna rivers interlinking projects also envisions an area more than twice the
size of Andhra Pradesh receiving extra water for irrigation and to even out the unwarranted
swings between droughts and floods.
 Later, Ministry of Water Resources and Central Water Commission formulated a National
Perspective Plan (NPP) in 1980 to study water resources development in the country and
transfer of water from surplus basin to deficit one to minimize regional imbalance.
 NWDA (National Water Development Agency) was formed under NPP to further
investigate and explore the possibilities of interlinking of rivers.
 As per NWDA, Inter basin water transfer is proposed in two components namely Himalayan
component and Peninsular component. Both the components together have 30 river-linking

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projects.
Major advantages of ILR:
1. Create the potential to increase agricultural production by an additional 100 per cent over
the next five years.
2. Avoid the losses of the type that occurred in 2002 to the extent of $550 million by the loss
of crops because of extreme draught or flood condition.
3. Save $ 565215000 a year in foreign exchange by avoiding importing oil.
4. Unify the country by involving every Panchayat as a share holder and implement agency.
5. Provide for enhancing the security of the country by an additional waterline of defense.
6. Provide employment to the 10 lakh people for the next 10 years.
7. Eradicate the flooding problems which occur again in the north-east and the north every
year.
8. Solve the water crisis situation by providing alternative, perennial water resources.
9. The large canals linking the rivers are also expected to facilitate inland navigation too.
10. Increasing food production from about 200m tones a year to 500m.
11. Boost the annual average income of farmers, from the present $40 per acre of land to over
$500.
Major disadvantages of ILR:
1. Environmental costs (deforestation, soil erosion, etc.)
2. Rehabilitation: not an easy task
3. Social unrest/Psychological damage due to forced resettlement of local people (for
example, Sardar Sarovar Project)
4. Political effects: strained relationship with neighbors (Pakistan, Bangladesh)
Benefits of River Interlinking:
There are many benefits that the proposed interlinking projects will bring about. They are
discussed below:
1. Interlinking rivers is a way to transfer excess water from the regions which receive a lot
of rainfall to the areas that are drought-prone. This way, it can control both floods and
droughts.
2. This will also help solve the water crisis in many parts of the country.
3. The project will also help in hydropower generation. This project envisages the building

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of many dams and reservoirs. This can generate about 34000 MW of electricity if the
whole project is executed.
4. The project will help in dry weather flow augmentation. That is when there is a dry
season, surplus water stored in the reservoirs can be released. This will enable a
minimum amount of water flow in the rivers. This will greatly help in the control of
pollution, in navigation, forests, fisheries, wildlife protection, etc.
5. Indian agriculture is primarily monsoon-dependent. This leads to problems in agricultural
output when the monsoons behave unexpectedly. This can be solved when irrigation
facilities improve. The project will provide irrigation facilities in water-deficient places.
6. The project will also help commercially because of the betterment of the inland
waterways transport system. Moreover, the rural areas will have an alternate source of
income in the form of fish farming, etc.
7. The project will also increase the defence and security of the country through the
additional waterline defence.

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Himalayan Rivers Development Component:

 This component mainly proposes to link Brahmaputra and its tributaries with the river
Ganga and Ganga with Mahanadi.
 In addition it also proposes to transfer surplus flows of the Eastern tributaries of Ganga to
the West.
 This component envisages construction of canal systems and storage reservoirs on the
principal tributaries of Ganga and Brahmaputra rivers in India, Nepal and Bhutan.
 This component would provide additional irrigation to about 22 MHa and power generation
of about 30000 MW besides flood control in Brahmaputra and Ganga basins.
 The Himalayan component will benefit not only India but also Nepal and Bangladesh.
 The Himalayan part of the India has 16 important river networks, has two sub-components:
(1) Transfer of Ganga and Brahmaputra rivers surplus waters to the Mahanadi Basin and
from Mahanadi to Godavari, Godavari to Krishna, Krishna to Pennar and Pennar to
the Cauvery river basins.
(2) Transfer of water from the Eastern Ganga tributaries to the western sects of the Ganga
and the Sabarmati river basins.
Proposed Fourteen Links in the Himalayan Component
1 Kosi-Mechi 2 Kosi-Ghagra
3 Gandak-Ganga 4 Ghagra-Yamuna
5 Sarda-Yamuna 6 Yamuna-Rajasthan
7 Rajasthan-Sabarmati 8 Chunar-Sone Barrage
9 Sone Dam-South Tributaries of Ganga 10 Brahmaputra-Ganga (MSTG)
11 Brahmaputra-Ganga (JTF)(ALT) 12 Farakka-Sunderbans
13 Ganga-Damodar-Subernarekha 14 Subernarekha-Mahanadi

1. Manas-Sankosh-Tista-Ganga (MSTG) Link

Interlinking of the Brahmaputra with the Ganga, the Subernarekha and the Mahanadi is proposed
to transfer waters of the Brahmaputra to benefit areas in Assam, West Bengal, Bihar, Jharkhand
and Orissa. The Manas-Sankosh-Teesta-Ganga link is an important link in this component. This
link envisages diversion of surplus water from Manas and Sankosh rivers in the Brahmaputra
basin to augment flows of the Ganga upstream of Farakka. A link to the Peninsular component
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through Subernarekha and Mahanadi is also envisaged. For this link high dams are proposed at
Manas and Sankosh with storage capacities of 8.75 BCM and 4.93 BCM, respectively (Singh
2002). A substantial part of the cost of these dams will be allocated to hydropower generation.
The 114 km long link canal between Manas and Sankosh will have a discharge capacity of 3,725
m3/s. Beyond Sankosh and up to the Teesta barrage, the link canal is 137 km long with a capacity
of 1,092 m3/s. Clearly, this will be a huge canal which will cross major drainages. The MSTG
link passes through the narrow chicken neck in West Bengal (north of Bangladesh) and may
have security aspects.
2. Ghaghra-Yamuna Link
The Ghagra-Yamuna link project is an inter-dependent link under the Himalayan Component of
NPP. A study reveals that the Ghagra River (known as Karnali in Nepal) at the proposed the
Chisapani dam site has surplus water. It is proposed that the existing requirement of water for the
Sarda Sahayak Pariyojna, Saryu Nahar Pariyojna and various pump canals would be met from
the proposed Gandak - Ganga link project and the water saved thereby could be diverted from
the proposed Chisapani reservoir through the Ghagra - Yamuna link canal. The height of
proposed dam is 175 m. A regulating dam downstream of the Chisapani dam is proposed with a
full reservoir level of 200 m and a minimum drawdown level 193 m. The link canal shall join
Yamuna River in Etawah district of Uttar Pradesh. The total length of the link canal would be
about 417 km with its depth varying from 8 m in the head reach to 5 m in the tail reach and the
width varying from 85.5 m in the head reach to 18 m towards the tail end.
3. Sarda-Yamuna-Rajasthan-Sabarmati Link Canal
This is a continuous link having a combination of three links, viz., the Sarda-Yamuna link, the
Yamuna-Rajasthan link, and the Rajasthan-Sabarmati link. This link canal is planned to divert
17,906 MCM (14.52 MAF) water of Himalayan rivers. Its length will be 1,835 km out of which
75 km will be in Gujarat State. A total of 4 states, Uttar Pradesh, Haryana, Rajasthan and
Gujarat, are to be benefited by this link. About 1,627 MCM (1.32 MAF) water has been allocated
to North Gujarat which is only 9% of the total divertible water at the canal head. A total 7.38
lakh ha area is to be irrigated by the Rajasthan-Sabarmati link, out of which 5.35 lakh ha in
Rajasthan and 2.03 lakh ha in Gujarat.
4. Yamuna-Rajasthan Link Canal Project
The Yamuna-Rajasthan link proposal is an extension of the proposed Sarda–Yamuna Link

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beyond the Yamuna to provide irrigation to the drought prone areas of Haryana and Rajasthan. It
envisages diversion of 8,657 Mm3 of water from the Sarda basin at Purnagiri. The Yamuna -
Rajasthan link is to take off from the right bank of proposed Yamuna barrage and passes through
the Karnal, Sonipat, Jind, Hisar and Bhiwani districts of Haryana and Churu, Hanumangarh,
Ganganagar, Bikaner, Jodhpur and Jaisalmer districts of Rajasthan and ends on the Jaisalmer-
Hamira-Shri Mohangarh Road at a distance of 4.5 km from village Kanod towards Jaisalmer.
The length of the link canal is 786 km, out of which 196 km lies in Haryana and the rest 590 km
in Rajasthan. The design discharge at head and tail are 572 cumec and 344 cumec, respectively.
The longitudinal slope of the canal is 1:20,000. The full supply depth and bed width of the canal
at head are 7 m and 53 m, respectively. The Yamuna - Rajasthan link will provide an annual
irrigation of 244,200 ha in the districts of Ganganagar, Bikaner, Jodhpur and Jaisalmer of
Rajasthan.

Peninsular Rivers Development Component:

 The main component of Peninsular Rivers Development is the “Southern Water Grid”
which is envisaged to link Mahanadi, Godavari, Krishna, Pennar, and Cauvery rivers.
 The peninsular scheme was envisaged to provide additional irrigation benefits of over 13
million ha.
 The peninsular part of the India has 16 major canals and 4 sub-components:
(1) Network of Mahanadi-Godavari-Krishna-Cauvery-Vaigai rivers;
(2) Network of west flowing rivers lies between south of Tapi and north of Bombay;
(3) Network of Parbati-Kalisindh-Chambal and Ken-Betwa rivers and
(4) Diverting the flow in some of the west flowing rivers to the eastern side of the country.
 As per NRLP (National Rural Livelihoods Project) the enroute irrigation under the
peninsular part of the country is expected to irrigate substantial areas.
 The amount of water diverted in the peninsular part may be 141 km3. The area to be
irrigated is situated in arid and semi-arid western and peninsular part of India
 The interlinking of Mahanadi, Godavari-Krishna-Cauvery rivers will require the
construction of a number of large dams and big canals.
 This system will be one of the largest and ambitious water transfer projects. The system
will require huge financial outlays and will have immense influence on economic, social and

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environmental growth of the region.

Proposed sixteen links in the Peninsular Component
Mahanadi(Manibhadra)-Godavari (d/s) 2 Godavari (Inchampalli)-Krishna
(Nagarjunsagar)
3 Godavari (Inchampalli Low Dam)-Krishna 4 Godavari (Polavaram)-Krishna
(Nagarjunsagar Tail Pond) (Vijaywada)
5 Krishna (Almatti) – Pennar 6 Krishna (Srisailam) – Pennar
7 Krishna (Nagarjunsagar) – Pennar 8 Pennar (Somasila)-Cauvery (Grand
(Somasila) Anicut)
9 Cauvery (Kattalai) – Vaigai – Gundar 10 Ken-Betwa
11 Parbati-Kalisindh-Chambal 12 Par-Tapi-Narmada
13 Damanganga-Pinjal 14 Bedti-Varda
15 Netravati-Hemavati 16 Pamba-Achankovil-Vaippar

1. Mahanadi (Manibhadra)-Godavari (Dowlaiswaram) Link

This link has been proposed between the Manibhadra reservoir on Mahanadi River to the
Dowlaiswaram barrage on the Godavari. It will divert 11,176 Mm3 of water out of which 3,854
Mm3 is proposed to be used for irrigation of en-route command area and 6,500 Mm3 would be
delivered at the Dowlaiswaram barrage. The Manibhadra reservoir has gross and live storages of
9,375 Mm3 and 6,000 Mm3, respectively. The total length of the link canal is about 932 km. The
design discharge of the link canal is 627 cumec as its head. The full supply levels at the head and
tail are 74.00 m and 13.81 m, respectively.
2. Godavari (Inchampalli)-Krishna (Nagarjunsagar) Link
This link canal is proposed to divert 16,426 Mm3 from the Inchampalli dam on Godavari River.
Out of this, 14,200 Mm3 will be transferred to the Nagarjunsagar reservoir on the Krishna River.
The total length of the link canal will be about 298.7 km, including a 9 km long tunnel. The FSL
at the head and tail are 142.00 m and 182.765, respectively, with a design discharge of 1,219
cumec. The link would involve a total lift of 116 m in four stages. For this purpose, power
needed would be 1,705 MW.
3. Godavari (Polavaram)-Krishna (Vijaywada) Link
This link canal has been proposed to divert 4,903 Mm3 which include 1,448 Mm3 for Polavaram

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RBC command, 2,265 Mm3 for the Krishna delta as committed under the Godavari Water
Dispute Tribunal award and 1,190 Mm3 for existing ayacut in the Krishna Delta. The proposed
Polavaram Barrage will be used to divert the Godavari water to the existing Prakasam Barrage of
the Krishna River at Vijayawada. The total length of the link canal will be 174 km and head
discharge will be 361 cumec. The canal will operate round the year. The FSL at the head and tail
are 40.23 m and 27.96 m, respectively.
4. Krishna (Srisailam)-Pennar Link
The link has been proposed to divert 2,310 Mm3 of water from the Srisailam reservoir to
Adinimmayapalli Anicut. The water would mostly flow through natural rivers and it is expected
that about 2,095 M m3 would reach the Somasila reservoir. This water is in exchange for surplus
waters of the Mahanadi transferred from the Godavari to the Nagarjunasagar. The total length of
the channel would be 171.30 km and design discharge will be 186 cumec. This channel would
run for 180 days in a year.
5. Pennar (Somasila) - Cauvery (Grand Anicut) Link
The aim of this link is to transfer 8,565 Mm3 of water from the Pennar to the Cauvery. Of this
quantity, 3,170 Mm3 would be used for en-route irrigation, 279 Mm3 for en-route domestic and
industrial uses, 876 Mm3 for the Chennai city water supply and 3,855 Mm3 would be transferred
to the Cauvery River at Grand Anicut. About 385 Mm3 water is likely to be lost during
transmission. The total length of the canal will be 538 km and its design discharge will be 616.38
cumec. The canal will be operated for 365 days in a year.
6. Cauvery (Kattalai Regulator) - Vaigai - Gundar Link
The link has been proposed to transfer 2,252 Mm3 of water from the Cauvery River to the Vaigai
River to provide irrigation to 353,337 ha annually. The FSLs of the 250 km long link canal at the
head and the tail will be 100.75 m and 78.865 m, respectively. This will be a lined canal which
would be operated round the year.
7. Krishna (Almatti) - Pennar Link
The canal linking Krishna (Almatti) with Pennar (587 km long) will take off from right bank of
the Almatti dam across the Krishna River in Karnataka with FSL of 510.00 m. The canal will run
through Karnataka and Andhra Pradesh before joining Maddileru, a tributary of the Pennar near
the Malakavemula village.

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8. Ken - Betwa Link

The Ken-Betwa and the Parbati-Kalisindh-Chambal links of the ILR project are the links on
which urgent attention is being focused by the Government. The Ken-Betwa link envisages
diversion of surplus waters of Ken basin to water deficit Betwa basin. This link canal will
provide irrigation to water short areas of upper Betwa basin of MP.
Table 5: Details of Interlinking of Rivers
Sl. Particulars Himalayan Peninsular Total
No Component Component
1 Link Canal 14 16 30
2 Major Reservoirs 9 27 36
3 Total Length of Link Canals (Km) 6100 4780 10880
4 Transferable Water (Km3) 33 141 174
5 Power Generation (MW) 30000 4000 34000
6 Project Cost of Irrigation unit ( Crores ) 185000 106000 291000

7 Project cost of Hydropower Unit (Crores) -------- -------- 269000

8 Additional Irrigation Area ( MHa ) 13 22 35

Issues and Challenges in Interlinking of River:

Inter-River Linking Project involves multifaceted issues and challenges related to economic,
ecological, and social costs.
Some of the issues and challenges in this regard are as follows:
1. Project feasibility: The project requires a large amount of money. Additionally, there is also
the requirement of huge structures and the huge expenditure may likely generate fiscal problems
that are difficult to handle All this requires a great engineering capacity. So, the cost and
manpower requirement is immense.
2. Environmental impact: The huge project will alter entire ecosystems. The wildlife, flora and
fauna of the river systems will suffer because of such displacements and modifications. Many
national parks and sanctuaries fall within the river systems. All these considerations will have to
be taken care of while implementing the project. The project can reduce the flow of fresh water
into the sea, thus affecting marine aquatic life, destruction of groundwater recharge and also

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increased methane emission from reservoirs are few of the other environmental damages.
3. Impact on society: Building dams and reservoirs will cause the displacement of a lot of
people. This will cause a lot of agony for a lot of people. They will have to be rehabilitated and
adequately compensated.
4. Controlling floods: Some people express doubts, as to the capability of this project to control
floods. Although theoretically, it is possible, India’s experience has been different. There have
been instances where big dams like Hirakud Dam, Damodar Dam, etc. have brought flooding to
Odisha, West Bengal, etc.
5. Inter-state disputes: Many states like Kerala, Sikkim, Andhra Pradesh, etc. have opposed the
river interlinking project.
6. International disputes: In the Himalayan component of the project, the effect of building
dams and interlinking rivers will have an effect on the neighboring countries like Bhutan, Nepal
and Bangladesh. This will have to be factored in while implementing the project. Bangladesh has
opposed the transfer of water from the Brahmaputra to the Ganga.

Ground Water:
 Ground Water it is usually defined as water found underground in the saturated zone
of rocks, i.e. at depths where the entire void space of the rock is filled with water.
OR
 Groundwater is the water present in spaces in soil or sands under the earth, or
between cracks of rocks lying deep inside.
 It is a term used to denote subsurface water that exists at pressure greater than or equal to
atmospheric pressure.
 As groundwater supplies are limited, they must be properly managed and protected against
undue exploitation and contamination by pollutants.
 Groundwater is found in two zones. The unsaturated zone, immediately below the land
surface, contains water and air in the open spaces, or pores. The saturated zone, a zone in
which all the pores and rock fractures are filled with water, underlies the unsaturated zone.
The top of the saturated zone is called the water table (Fig-1). The water table may be just
below or hundreds of feet below the land surface.

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Fig-1 Ground water zones

Ground Water Potential in India:
About two-third of the total land area in the country comprises consolidated formations, 75% of
this being made up of crystalline rocks and consolidated sediments, the remaining 25% being
trap.
The remaining one-third of the total land area comprises semi-consolidated and unconsolidated
formations like alluvial tracts. There is sample scope for development of ground water in these
areas.
A flirtation of potential areas of ground water in India and their hydraulic characteristics are
given in the following.
Areas of Ground Water Potential in India:
1. Springs in the Himalayan Highlands: All types or rocks are present the chief types include
granites, basalts, sandstones, limestones, shales, conglomerates, slates, quartzites, gneisses,
schists and marbles.
2. Fresh water sediments of Kashmir valley: The Kashmir valley which was a vast lake during

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the Pleistocene times, shows a large scale development of fresh water sediments.
3. Indo-Gangetic alluvium: Coarse sands, gravel and boulders of variable thickness-3 to 60 m.
Water commonly hard; shallow and deep aquifers interconnected. The exploitation of
ground water is usually done by using spiral augers hand boring (H.B.) sets, cable tool and
rotary rigs.
4. Coastal alluvium-Malabar and Coromandel coastal areas: Depth 15-150 m, yield =12-50
m3/h; low TDS; water in tertiary aquifer associated with lignite or carbonaceous clay is
sulphuretted and contains iron > 1 ppm. Extensive saline patches occur in Ramna
Tirunelveli, Ongole, Nellore and Krishna districts.
5. Cretaceous sandstones of Kathiawar and Kutch areas: Moderately potential aquifers depth
100-300 m, water commonly brackish with TDS 2000-5000 ppm.
6. Mesozoic sandstones of the Lathi region in Rajasthan (Jaisalmer, Barmer, Bikaner):
Moderately potential aquifers, depths 100-150 m, yield =45-150 m3/hr water is generally
brackish to saline.
7. Cavernous limestones of Vindhyan system in Borunda and Ransingaon areas in Jodhpur
district: Potential aquifers Potable water and fractured up to 150 m.
Recharge of some arid zones in Haryana and Rajasthan can be done by diverting the flood
waters of Yamuna river through Saraswathi and Ghaggar rivers by making suitable
connections.
8. Doon valley gravels: Boulders, pebbles, gravel, sand and clay possibly of fanglomeratic
and collovial origin. Major portion of the valley is hilly, sloping ground.
9. Quaternary alluvium of Narmada, Purna, Tapti, Chambal and Mahanadi rivers: Thickness
75-150 m (lenses of sand and gravel); tubewell wield 20-150 m³/hr; good quality water
with TDS 100-500 ppm.
10. Vesicular basalts in the Deccan trap formations of Maharashtra and Madhya Pradesh: Form
good aquifers; ground water occurs under both confined and unconfined conditions in the
Satpura range and Malwa plateau; tubewell yields in Indore, Bhopal, Raisen, Vidisha and
Sagar districts.
11. Carbonate rocks with solution cavities in Madhya Pradesh: In the Vindhyan, Cuddapah and
Bijawar region, the carbonate rocks with interconnected solution cavities and caverns form
good aquifers.

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12. Dharwarian and Bundelkhand granite region of Madhya Pradesh: Igneous and
metamorphic rocks; the movement of water is mainly through joints and openings. The
water quality in all regions of MP is generally good, except in the water logged areas of the
Chambal valley.
13. Tertiary snadstones and quaternary sand to pebble beds in the Godavari-Krishna
interstream area: Form potential aquifers with artesian conditions.
14. Alluvium in Palar and Kortallaiyar-Araniyar rivers in Tamil Nadu: Form potential aquifers:
water of good quality. Tertiary sediments of Cauvery delta: The tertiary sediments in
Tanjore and Arcot districts form extensive aquifers up to 200 m depth. Water is of good
quality;
15. Granitic gneisses and schists of Karnataka: The principle rock types of Karnataka are
igneous and metamorphic granites, geneisses and schists of Precambrian age and basalt of
the Deccan trap of Eocene-Upper Cretaceous age in the extreme northern part of the state.
16. Upper Gondwana sandstones and the alluvial tract of Orissa: Form potential aquifers.
17. The Quaternary sediments in the deltaic tract around Digha, district Midnapur, West
Bengal: These are of depth 140 m and yield fresh water.
18. The multilayered Lacustrine aquifer in Nepal in the centre of the Kathmandu valley basin:
It has a depth of sediment of > 450m deposits becoming coarser towards the north where
most of the catchment is mountainous. The sediment consists of silt, coarse sand and
cobbles with electrical resistivity ranging from 40-120 ohm-m.
19. Karstic limestones in the north coastal belt of Sri Lanka: Nine-tenths of the area of the
island are underlain by the crystalline rocks such as gneisses, schists, quartzites and
crystalline limestones of the Precambrian basement complex; low yields are obtained from
the locally developed fissures and fractures. The soil overburden is 2-15 m and large
diameter dug wells are generally suitable.
20. Thermal and mineral springs: They are found in many parts of India-Bombay, Punjab,
Bihar, Assam, in the foothills of Himalayas and Kashmir.

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Conjunctive Use:

Conjunctive Use of Ground Water:

 Surface water and ground water may be viewed as two different forms of occurrence of the
same total water resources.
 Tube well schemes may be integrated with the canal irrigation schemes by suitably spacing
them along a line in between the distributory and the drainage line and so designing that the
subsoil water level is kept steady at a desired level.
 The tube wells intercept the canal seepage and serve as an anti-water logging measure and
enable the benefit of irrigation facilities to be spread to wider areas. Supplemental ground
water irrigation is proposed to be introduced in the command areas of a number of major
irrigation systems like the Yamuna canal, the Cauvery and the Krishna deltas to enable
intensive agricultural development.
 Optimum development of water resources can be achieved by the conjunctive and ground
waters. Ground water recharge occurs in nature by seepage from canals and reservoirs and
return flow from irrigation. It can be augmented by artificial methods such as spreading of
storm water in ponds or basins, recharge wells, pits and shafts.
 The usable capacity of the ground water reservoir can be developed by planned extractions
of ground water during periods of low precipitation while subsequent replenishment can be
made during periods of surplus surface supply.
 Large ground water reservoirs thus developed not only meet the deficiencies of the surface
supplies in seasons of drought but also supplement them to a large extent. These conjunctive
operations result in a more economic yield as they provide more water at a lower average
cost.
 Tubewell schemes can be integrated with the canal irrigation scheme by suitably spacing
them along the drainage lines in the distribution area.
The benefits accruing from the conjunctive use of waters are:
1. A large sub-surface storage at a relatively lower cost and safe against any risk of dam
failures.
2. Provides water supplies during a series of drought years while a surface storage can at the
most tide over one such year.

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3. Efficient water use from well spaced wells due to smaller surface distribution system than
a canal irrigation scheme.
4. Water table can be controlled by pumping from wells and prevent water logging in canal
irrigated areas and reduce land subsidence due to reduced ground water levels
particularly in confined aquifers.
5. Both water conservation and flood protection can be achieved simultaneously.
6. A sub-surface scheme can be developed in a shorter period while it takes 10-15 years for
the completion of a big surface water project.
7. No evaporation and percolation losses, thus obviating the construction of expensive storm
and seepage drains.
8. In project under conjunctive use of waters, tube well loads can be reduced by releasing
surface water for irrigation during periods of peak power demand thus resulting in lower
power costs.
9. Crop water requirements can be ensured right through the year using surface water during
the monsoons and ground water supplies when the surface water is not available.
10. Ground water and surface water can be mixed in proper proportions to obtain a desired
water quality for irrigating certain crop types when the ground water has a higher salt
concentration only certain salt tolerant crops can be grown.
11. Integration of the two types of schemes can be obtained with the existing water resources
without loss of earlier investment.

Recharge of Ground Water:

 Groundwater Recharge is a (hydrologic) process where the water from the surface of the
earth seeps downwards and gets collected in aquifers. So, the process is also known as
deep drainage or deep percolation.
 Recharge occurs both naturally (through the water cycle) and through anthropogenic
processes (i.e. artificial groundwater recharge), where rainwater and or reclaimed water is
routed to the subsurface.
The different methods of groundwater recharge are:
1. Spreading Basins
2. Recharge Pits and Shafts

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3. Ditches
4. Recharge Wells
5. Harvesting in Cistern from Hill Sides
6. Subsurface Dams
7. Farm Ponds
8. Historical Large Well across Streamlet
9. Check Dams.
1. Spreading Basins: This method involves surface flooding of water in basins that are
excavated in the existing terrain. For effective recharge highly permeable soils are suitable and
maintenance of a layer of water over the highly permeable soil is necessary.
When direct discharge is practiced the amount of water entering the aquifer depends on three
factors the infiltration rate, the percolation rate, and the capacity for horizontal water movement.
At the surface of aquifer, however, clogging occurs by deposition of particles carried by water in
suspension or in solution, by algae growth, colloidal swelling and soil dispersion, microbial
activity, etc. Recharge by spreading basins is most effective where there are layer below the land
surface and the aquifer and where clear water is available for recharge.

2. Recharge Pits and Shafts: The artificial recharge systems such as pits and shafts could be
effective in order to access the dewatered aquifer. The rate of recharge has been being found to
increase as the side slope of the pits increased.
Unfiltered runoff water leaves a thin film of sediments on the sides and bottom of the pits, which

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require maintenance in order to sustain the high recharge rates.

Shafts may be circular, rectangular or square cross-section and may be back filled by porous
materials.
Excavation may be terminating above the water table. Recharge rates in both shafts and pits may
decrease with time due to accumulation of fine-grained materials and the plugging effect brought
by microbial activity.

3. Ditches: A ditch is described as a long narrow trench, with its bottom width less than its
depth. A ditch system is designed to suit topographic and geological condition that exists at the
given site.
A layout for a ditch and flooding recharge project could include a series of trenches running
down the topographic slope.
The ditches could terminate in a collection ditch designed to carry away the water that does not
infiltrate in order to avoid ponding and to reduce the accumulation of fine materials.

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4. Recharge Wells: Recharge or injection wells are used to directly recharge the deep-water
bearing strata. Recharge wells could be dug through the material overlaying the aquifer and if the
earth materials are unconsolidated, a screen can be placed in the well in zone of injection.
Recharge wells are suitable only in areas where thick impervious layer exists between the surface
of the soil and the aquifer to be replenished. They are also advantageous in areas where land is
scarce. A relatively high rate of recharge can be attained by this method. Clogging of the well
screen or aquifer may lead to excessive buildup of water level in the recharge well.

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5. Harvesting in Cistern from Hill Sides: In this method construction of small drains along
contours of hilly area are done so that the runoff in these drains are collected in a cistern, which
is located at the bottom of a hill or a mountain. This water is used for irrigation or for drinking
purpose and the water is of good quality.

6. Subsurface Dams: Ground water moves from higher-pressure head to lower one. This will
help in semi-arid zone regions especially in upper reaches where the ground water velocity is
high. By exploiting more ground water in upper reaches more surface water can be utilized
indirectly, thereby reducing inflow into lower reaches of supply. Ground water is stored either in
natural aquifer materials in sub-surface dams or in artificial sand storage dam.

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7. Farm Ponds: These are traditional structures in rain water harvesting. Farm ponds are small
storage structures collecting and storing runoff waste for drinking as well as irrigation purposes.
As per the method of construction and their suitability for different topographic conditions farm
ponds are classified into three categories such as excavated farm ponds suited for flat
topography, embankment ponds suited for hilly and ragged terrains and excavated cum
embankment type ponds.
Selection of location of farm ponds depend on several factors such as rainfall, land topography,
soil type, texture, permeability, water holding capacity, land-use pattern, etc.

8. Historical Large Well across Streamlet: If any historical wells are located near the
streamlet, then allow the water into the well from streamlet by connecting drains. In this case the
historical wells act as a recharge well so that ground water can be improved.

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9. Check Dams: Check dams are small barriers built across the direction of water flow on
shallow river and streams for the purpose of rain water harvesting. The small dams retain excess
water flow during monsoon rains in a small catchment area behind the structure.
Pressures created in the catchments area send the impounded water into the ground. The major
environmental benefit is the replenishment of nearby ground water reserves and wells. The most
common case of check dams is to decrease the slope and velocity of a stream to control erosion.

Benefits of Groundwater Recharge:

There are following advantages of artificial recharging of groundwater aquifers:
 Subsurface storage space is available free of cost and inundation is avoided
 Evaporation losses are negligible and temperature variations are minimum
 Quality improvement by infiltration through the permeable media
 It has no adverse social impacts such as displacement of population, loss of scarce
agricultural land etc.
 It is a environment friendly technology that controls soil erosion and flood like situations,
and provides sufficient soil moisture during dry spell or water deficit conditions.
 Water stored in soil profile is relatively immune to natural and man-made catastrophes.

Contamination of Ground Water:

 Groundwater, under most conditions, is safer and more reliable for use than surface water.
Part of the reason for this is that surface water is more readily exposed to pollutants from

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factories. This by no means says that groundwater is invulnerable to contamination.

 Although it is not as vulnerable as surface water, contaminates can still reach wells and
therefore households. Any chemicals that are easily soluble and penetrate the soil are prime
candidates for groundwater pollutants.
 Groundwater contamination occurs when man-made products such as gasoline, oil, road
salts and chemicals get into the groundwater and cause it to become unsafe and unfit for
human use.
 Materials from the land's surface can move through the soil and end up in the groundwater.
For example, pesticides and fertilizers can find their way into groundwater supplies over
time.
 Road salt, toxic substances from mining sites, and used motor oil also may seep into
groundwater. In addition, it is possible for untreated waste from septic tanks and toxic
chemicals from underground storage tanks and leaky landfills to contaminate groundwater.
 A potential pollution problem can still reach a well mile away through underground water
currents.
Sources of Groundwater Contamination:
1. Natural Sources
2. Storage Tanks
3. Septic Systems
4. Uncontrolled Hazardous Waste
5. Landfills
6. Chemicals and Road Salts
7. Atmospheric Contaminants:
8. Surface Impoundments
9. Sewers and Other Pipelines
10. Improperly Constructed Wells
11. Improperly Abandoned Wells
12. Poorly Constructed Irrigation Wells
13. Mining Activities
1. Natural Sources: Some substances found naturally in rocks or soils such as iron, manganese,
arsenic, chlorides, fluorides, sulfates, or radio nuclides, can become dissolved in ground water.

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Other naturally occurring substances, such as decaying organic matter, can move in ground water
as particles. Whether any of these substances appears in ground water depends on local
conditions. Some substances may pose a health threat if consumed in excessive quantities; others
may produce an undesirable odor, taste, or color. Ground water that contains unacceptable
concentrations of these substances is not used for drinking water or other domestic water uses
unless it is treated to remove these contaminants.
2. Storage Tanks: May contain gasoline, oil, chemicals, or other types of liquids and they can
either be above or below ground. There are estimated to be over 10 million storage tanks buried
in the United States and over time the tanks can corrode, crack and develop leaks. If the
contaminants leak out and get into the groundwater, serious contamination can occur.
3. Septic Systems: Onsite wastewater disposal systems used by homes, offices or other buildings
that are not connected to a city sewer system. Septic systems are designed to slowly drain away
human waste underground at a slow, harmless rate. An improperly designed, located,
constructed, or maintained septic system can leak bacteria, viruses, household chemicals, and
other contaminants into the groundwater causing serious problems.
4. Uncontrolled Hazardous Waste: In the U.S. today, there are thought to be over 20,000
known abandoned and uncontrolled hazardous waste sites and the numbers grow every year.
Hazardous waste sites can lead to groundwater contamination if there are barrels or other
containers laying around that are full of hazardous materials. If there is a leak, these
contaminants can eventually make their way down through the soil and into the groundwater.
5. Landfills: Landfills are the places that our garbage is taken to be buried. Landfills are
supposed to have a protective bottom layer to prevent contaminants from getting into the water.
However, if there is no layer or it is cracked, contaminants from the landfill (car battery acid,
paint, household cleaners, etc.) can make their way down into the groundwater.
6. Chemicals and Road Salts: The widespread use of chemicals and road salts is another source
of potential groundwater contamination. Chemicals include products used on lawns and farm
fields to kill weeds and insects and to fertilize plants, and other products used in homes and
businesses. When it rains, these chemicals can seep into the ground and eventually into the
water. Road salts are used in the winter time to put melt ice on roads to keep cars from sliding
around. When the ice melts, the salt gets washed off the roads and eventually ends up in the
water.

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7. Atmospheric Contaminants: Since groundwater is part of the hydrologic cycle, contaminants

in other parts of the cycle, such as the atmosphere or bodies of surface water, can eventually be
transferred into our groundwater supplies.
8. Surface Impoundments: Surface impoundments are relatively shallow ponds or lagoons used
by industries and municipalities to store, treat, and dispose of liquid wastes. As many as 180,000
surface impoundments exist in the United States. Like landfills, new surface impoundment
facilities are required to have liners, but even these liners sometimes leak.
9. Sewers and Other Pipelines: Sewer pipes carrying wastes sometimes leak fluids into the
surrounding soil and ground water. Sewage consists of organic matter, inorganic salts, heavy
metals, bacteria, viruses, and nitrogen. Other pipelines carrying industrial chemicals and oil brine
have also been known to leak, especially when the materials transported through the pipes are
corrosive.
10. Improperly Constructed Wells: Problems associated with improperly constructed wells can
result in ground water contamination when contaminated surface or ground water is introduced
into the well.
11. Improperly Abandoned Wells: These wells can act as a conduit through which
contaminants can reach an aquifer if the well casing has been removed, as is often done, or if the
casing is corroded. In addition, some people use abandoned wells to dispose of wastes such as
used motor oil. These wells may reach into an aquifer that serves drinking supply wells.
Abandoned exploratory wells (e.g., for gas, oil, or coal) or test hole wells are usually uncovered
and are also a potential conduit for contaminants.
12. Poorly Constructed Irrigation Wells: These wells can allow contaminants to enter ground
water. Often pesticides and fertilizers are applied in the immediate vicinity of wells on
agricultural land.
13. Mining Activities: Active and abandoned mines can contribute to ground water
contamination. Precipitation can leach soluble minerals from the mine wastes (known as spoils
or tailings) into the groundwater below. These wastes often contain metals, acid, minerals, and
sulfides. Abandoned mines are often used as wells and waste pits, sometimes simultaneously. In
addition, mines are sometimes pumped to keep them dry; the pumping can cause an upward
migration of contaminated ground water, which may be intercepted by a well.

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Sea Water Ingress/ Sea Water Intrusion:

 Sea Water Ingress or Seawater intrusion is the movement of seawater into fresh water
aquifers due to natural processes or human activities.
 Seawater intrusion can naturally occur in coastal aquifers, owing to the hydraulic connection
between groundwater and seawater. Because saline water has a higher mineral content than
freshwater, it is denser and has a higher water pressure.
 Seawater intrusion is caused by decreases in groundwater levels or by rises in seawater
levels.
 When you pump out fresh water rapidly, you lower the height of the freshwater in the
aquifer forming a cone of depression. The salt water rises 40 feet for every 1 foot of
freshwater depression and forms a cone of ascension.
 Certain human activities, especially groundwater pumping from coastal freshwater wells,
have increased saltwater intrusion in many coastal areas.
 Water extraction drops the level of fresh groundwater, reducing its water pressure and
allowing saltwater to flow further inland.
 Use of salt for highways deicing is another source of contamination when this salt washes
off roads it may easily move with percolating water into underground aquifers.
 An additional problem is created by the fact that piles of salt to be used for deicing have
frequently been stored uncovered along roads: rain or snowmelt can dissolve this salt and,
though percolation, introduce it into aquifers.
 Other contributors to saltwater intrusion include navigation channels or agricultural and
drainage channels, which provide conduits for saltwater to move inland.
 Sea level rise caused by climate change also contributes to saltwater intrusion. Saltwater
intrusion can also be worsened by extreme events like hurricane storm surges.
 High concentrations of chloride can make water unfit for human consumption and for many
industrial uses, but the human health-related problems have not been carefully observed yet.
 However, high concentrations of sodium ion can contribute to certain heart disease or high
blood pressure, particularly in susceptible individuals.
 High concentration of chlorine has bad effects on the environment as well: it can produce
leaf burn and even defoliation in sensitive crops; in lakes can increase the presence of metals

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in waters and prevent the distribution of oxygen and nutrients and thus harm aquatic life.
 Seawater intrusion which can lead to groundwater quality degradation, including drinking
water sources, and other consequences.

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Causes of saline water intrusion:

The reasons, for which fresh water aquifers are contaminated by saline water intrusion, are listed
below:
1. Pumping of fresh water increases the saline water intrusion.
2. Untimely water use, unplanned shrimp culture, insufficient management systems,
inadequate or poorly maintained infrastructure and weak water governance systems at
local.
3. Lateral or horizontal intrusion occurs when excessive water withdrawals from a coastal
aquifer cause saline water from the coast to move towards the inland.
4. Vertical movement or upcoming of saline water can occur near a discharge well when
water moves toward the well tip and saline water in the deeper aquifers rises up.
5. Cross-aquifer contamination can be caused by wells that are open to multiple aquifers or
have casings that have been corroded or broken.
Factors affecting saline water intrusion:
The following factors which affect saline water intrusion are listed below:
1. Type of aquifer and its geometry and geology.
2. Irrigation and agricultural practices.
3. Rainfall intensities and frequencies.
4. Total rate of groundwater withdrawals compared to recharge rates.
5. Presence of freshwater drainage canals that lack salinity control structures.
6. Distance of stresses, such as wells and drainage canals, from the source of saline water
intrusion.
7. Length of time for lowering of the aquifer levels.
8. Long-term changes in sea level initiated by the tidal fluctuations.
9. Seasonal and annual variations in groundwater recharge and evapotranspiration rates.
10. Geologic structures and the distribution of hydraulic properties of an aquifer including the
presence of confining units which can prevent the saline water intrusion.
Solution or Methods for Controlling Saline Water Ingression:
The methods for controlling or preventing saline water ingression. They are categorised by
1. Keeping basin water level high,
2. Creating a fresh water ridge near sea,

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3. Creating pumping trough or extraction barrier trough,

4. Developing artificial subsurface barriers,
5. Adopting rainwater harvesting technology and artificial recharging structures and
implementing aquifer improvement plans.
1. Keeping basin water level high: Although it is manifested that reduction in pumping draft
would tend to affect a rise in groundwater levels, additional comment if warranted regarding
effects of arrangement of pumping pattern. If the site of major withdrawals is transferred from
the coastal segment of a basin to an area further inland, the landward hydraulic gradient inland
from the trough would be increased. Such a condition would tend to halt or slow the inflow of
saline water. Groundwater levels in the overdrawn aquifers can be raised and maintained above
sea level through artificial recharge utilizing surface spreading, injection wells otherwise both.

2. Creating a fresh water ridge near the sea: The method would require the continuous
maintenance of a fresh water ridge in the principal water bearing deposits along the coast
through the application of water by surface spreading or injection wells otherwise both. Effects
of a fresh water ridge or mound on seawater ingression are shown in Figure 5(a) and Figure 5(b)
for unconfined aquifer and confined aquifer, respectively. The actual formation of a ridge along
the coastal segment of a groundwater basin by use of injection wells otherwise surface water
spreading or combination of both would depend on whether free groundwater or pressure
condition exists, as determined by geologic and engineering investigations.

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Figure 5 (a) & (b): An injection ridge seawater barrier and an extraction type of seawater
barrier in unconfined and confined groundwater basins, respectively.

3. Creation of pumping trough or extraction barrier trough: Development of an extraction

barrier would require retaining a continuous pumping trough near ocean. Pumping trough can be
created and developed by means of a row of pumping wells, properly located along the seacoast.
The wells would create a mix of fresh and saline water and could result in the waste of
substantial quantities of fresh water. Hydrologic conditions with an extraction type of seawater
barrier in unconfined aquifer and confined aquifer are depicted in Figure 6(a) and Figure 6(b),
respectively.

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Figure 6 (a) & (b): Hydrologic conditions with an extraction type of seawater barrier and
an injection ridge seawater barrier in an unconfined and confined groundwater basin.

4. Development of artificial subsurface barriers: This method involves the establishment of a

subsurface barrier to reduce the permeability of water bearing deposits sufficiently to prevent the
seawater inflow into fresh water strata. This reduction in the permeability could be achieved by
the construction of a subsurface barrier of sheet pilling or other form of physical structure as
depicted in Figure 7. Emulsified asphalt, plastics and other materials might be injected to form a
vertical zone of reduced permeability that would retard or prevent seawater ingression into
freshwater portions of aquifer.

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Figure 7: Subsurface barrier.

5. Rainwater harvesting technology: Rainwater is the foremost appearance of water into
hydrological cycle and a major source of water. Oceans, rivers, lakes, ponds and groundwater are
secondary resources of water. The present situation is much more dependent on secondary
resources of water. Rain is only resource to feed all these secondary sources. The meaning of
rainwater harvesting is to collect rain and runoff in towns and villages while taking suitable
measures to not allow the polluting agents to mix with clean water in catchments. Rainwater
harvesting provides many purposes. It may provide irrigation water and drinking water; reduce
storm water discharge, floods in urban area and overcapacity of sewage handling plants; enhance
groundwater recharge; lessen saline water ingression in coastal aquifer, etc.

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