The variations of the magnitude of annual rainfall in India are quite marked. It varies from an average of about 300cm in northeastern states of India to less than 15cm in its northwestern part in the semi arid and arid parts of Rajasthan and Gujarat. Also the Himalayan rivers flowing in the northern part of India are snow fed and perennial, the peninsular rivers are rain fed and seasonal. The hydrological, climatic and topographical factors cause recurrence of floods in certain parts of the country and some parts may be under scarcity of water.
The diversified distribution of dominant water demanding features such as density of population, irrigable land is the context that the interlinking of rivers for inter basin transfer of water on a national scale has been `haunting individuals and even engineers for more than a century. Linking of rivers and trans basin diversion of water is not new in our country and also other parts of the world. Diversion of river waters for cultivation of crops has been taking place from historical times. During recent times, the linking of rivers such as the Beas-sultlej link and the diversion of waters on a large scale to far off areas in rajasthan through the rajasthan canal is an excellent example. The 440 Km Narmada canal with a capacity of 40,000cusecs in the initial reach is also to supply water to some of the districts in Rajasthan. The diversion of 40,000 cusecs of Ganga waters at Farakka Barrage has also proved very useful. The present National plan for linking rivers has several components. The main ones are :
(i) Himalayan components and
(ii) Peninsular riverlinks system
The implementation of the Himalayan component depends on the co-operation of Nepal as the major tributaries of the Ganga originate in that country.
Need for Interlinking OF RIVERS: -
Somewhere people loose their lives, home, belongings due to floods or droughts. In either case people don’t have water to drink, a basic necessity for life.
Requirement of water: -
(i) Irrigation-1,060 cubic meter
(ii) Domestic water supply and live stock – 90 billion Cu-m
(iii) Agriculture – 600 billion Cu-m
(iv) Industry – 64 billion Cu-m
(v) Energy – 50 billion Cu-m
Total – 1,864 billion Cu-m
Thus the requirement of water will exceed the utilizable water resources of 1,122 billion Cu-m. The position of agriculture is no better. Today agriculture has become most unattractive job because of the floods and droughts. The Indian agriculture has been a “Gambling in monsoon”. The floods and droughts have remained permanent visitors causing havoc with Indian economy.
We witness frequent floods in some parts of the country causing havoc, devastation, damages, human suffering besides, a huge amount of public funds being spent on relief measures.
On the other hand, there is a large stretch of land vertically passing through the country as rain shadow area in the name of drought prone area, commencing from the Ramanathapuram in the south and ending up somewhere in the Ganganagar in Rajasthan traversing several districts in almost every state in south India. Many farmers died by making suicides in Karnataka due to lack of rainfall in the last five years.
Concept of interlinking of rivers: -
The concept of interlinking of rivers evolved during 1950s. At that time, the UN promoted such projects as part of “Stability and Peace”. That was the time when big projects and technology were seen as the answer to poverty. It was also the time when many countries, after gaining independence from colonial powers wanted to express their national confidence through such major projects. The interlinking of Indian rivers proposal originated at the same time as the world became fascinated with large water infrastructure projects.
Rivers, which join, act as drainage channels and entire river system so formed drains a specified area called the basin of that system. Thus intra-basin interlinking of rivers is a natural geomorphologic process. As distinct from this, interlinking of rivers belonging to altogether different basins is not a natural process and can only take place through man made devices. Essentially inter-basin transfer of water has been done through surface irrigation projects, in which lower portion of command areas include areas in the adjoining river basin through which water is conveyed through ridge canals. Such inter-basin transfer however, is marked by the following characteristics,
(i) Transfer of water is invariably to the adjoining basins and not across basins.
(ii) Irrigation channels are generally ridge channels suitable for distribution of water as distinct from valley channel suitable for drainage of water.
(iii) Water transferred is directly used, for irrigation in this case and not brought to a river in the receiving basin and hence does not constitute interlinking of rivers, and
(iv) Transfer of water takes place through gravity flows and does not require lifting by pumps.
From the above points, it is clear that interlinking of rivers through inter-basin transfer of water is different from intra-basin linking of rivers. Interlinking of rivers that is being talked about as a national programme will have the following characteristics:
(i) It envisages linking of rivers belonging to different basins, which may or may not be adjacent.
(ii) The primary purpose of link channels will be to transfer water of a river to another river of a different basin. Any other use of a link channel will be incidental to serve the primary purpose.
(iii) Neither the lateral slope available to the tributaries linking with their parent channel nor the longitudinal slope available to ridge channels for distribution of water will be available to link channels. Hence, the link channels will almost invariably have to operate with adverse slope, making pumping or input of energy necessary. Also, the link channels, as any other channel, will be subject to seepage losses of varying magnitudes depending upon their surface and subsoil conditions.
(iv) As the objective of interlinking of rivers in the present context is to transfer water from water-surplus rivers/basins to water-deficit rivers/basins, the direction of flows in the link channel and its alignment will be determined accordingly.
NATIONAL WATER DEVELOPMENT AGENCY
National water development agent (NWDA) was set up in July, 1982 as Autonomous Society under the Societies Registration Act, 1860 under Ministry of Water Resources to carry out the water balance and other studies on a scientific and realistic basic for optimum utilisation of Water Resources of the Peninsular Rivers System for preparation of feasibility reports for interbasin transfer of water and thus to give concrete shape to Peninsular rivers Development Component of National Perspective Plan envisage by the Ministry of Water Resources. In 1990 NWDA was also entrusted with the task of Himalayan Rivers Development Component of the National Perspective.
NWDA has so far identified and investigated 16 links for peninsular rivers and 14 for the Himalayan Rivers and has carried out pre-feasibility studies with respect to about 6 of them. The Supreme court of India, in response to a public interest litigation(PIL) against inordinate delay of rivers a task for which NWDA was created about two decades ago. The president of India an avowed scientist in his own right also lent his wisdom in favour of the grand scheme. In accordance with the directive of the Supreme Court , the Task Force has been set up with a time bound mandate of taking various steps towards the implementation of the project in a period of 10 years at a tentatively estimated cost of Rs.5,60,000 crore.
The Agency is headed by the Director General Executive Officer of the Society, responsible for the proper administration of the affairs and funds of the Society and for co-ordination and general supervision of the activities of the Society. The Head Quarter for the Agency is ay New Delhi. It has two field organisations, each headed by a Cheil Engineer, 5 circles each headed by a Superintending Engineer, 15 Divisions each headed by an Executive Engineer and 8 Sub-Divisions each headed by an Assistant Executive Engineer/Assistant Engineer.
OBJECTIVES OF NWDA
(a) To promote scientific development for optimum utilisation of water resources in the country.
(b) To carry out detailed surveys and investigations of possible reservoir sited and interconnecting links in order to establish feasibility of the proposal of Peninsular Fivers Development and Himalayan Rivers Development Components forming part of National Perspective for Water Resources Development prepared by the them Ministry of Irrigation ( now Ministry of Water Resources and Central Water Commission)
(c) To carry out detailed studies about quantum of water in various Peninsular River Systems and Himalayan River Systems and which can be transferred to other basins/States after meeting reasonable needs of basin States in the foreseeable future.
(d) To prepare feasibility reports of various components of the scheme relating to Peninsular Rivers Development and Himalayan Rivers Development.
(e) To take such other actions the Society may consider necessary, incidental supplementary or conducive to the attainment of above objectives.
NATIONAL PERSPECTIVE FOR WATER RESOURCES DEVELOPMENT
The erstwhile ministry of irrigation (now ministry of water resources) and the Central Water Commission had formulated in 1980 a National Perspective Plan for optimum utilization of water resources in the country which envisages inter basin transfer of water from surplus to deficit areas. Apart from diverting water from rivers which are surplus in ultimate stage of development to deficit areas the plan enables flood moderation also. The National Perspective Plan comprises of two main components
(f) Himalayan rivers Development
(g) Peninsular rivers Development
(a) Himalayan Component
NWDA has completed the pre-feasibility studies of fourteen links in the Himalayan component too. They are namely
- Manas-Sankosh-Tista Ganga link,
- Jogighopa-Tista-Farakka link,
- Ganga-Damodar-Subernarekha link,
- Subernarekha-Mahanadi link,
- Farakka-Sunderbans link,
- Gandak-Ganga link,
- Ghaghara -Yamuna link,
- Sarda-Yamuna link,
- Yamuna-Rajasthan link,
- Rajasthan-Sabarmati link,
- Chunar-Sone Barrage link,
- Sone Dam-Southern tributaries of Ganga link,
- Kosi- Ghaghara link and
- Kosi-Mechi link
(b) Peninsular Components
In this component, NWDA studied in depth water balance studies of various major river basins including Mahanadi, Godavari, Krishna, Pennar, Cauvery, Vaigai, West flowing rivers of Kerala, Karnataka, north of Bombay and south of Tapi and southern tributaries of Yamuna to establish water surplus and deficit regions. These studies indicate that while Mahanadi and Godavari basins are water surplus, other basins in Peninsular India such as Krishna, Pennar, Cauvery and Vaigai are water deficit. As a next step, pre-feasibility studies for 16 probable links were carried out, of which 7 feasibility studies have also been completed by NWDA. Also, these studies suggest that it is technically possible and economically viable to transfer water from the surplus river basins to the deficit ones. Each link, in this component is briefly described here. This information is tentative and likely to change at DPR stage.
15. Ken-Betwa Link
Benefits from peninsular and Himalayan rivers development components
On implementation of the proposed National Perspective Plan for inter-basin transfer of water, accrual of irrigation benefits would be to the extent of about 35 million ha (25 M-ha from surface waters and 10M-ha by increased use of ground water) which will be over and above the ultimate potential of 140 M-ha from major, medium and minor irrigation projects and generation of 34 MKW of hydropower apart from the benefits of flood control, navigation, water supply, fisheries, salinity ingress and pollution control.
Current and projected gross utilization in 2050 of surface and ground water
(Billion cubic meter)
| Basin | Mean Flow | current | Projected | Percent increase | ||||||
| Surface | Ground | Total | Surface | Ground | Total | Surface | Ground | Total | ||
| Mahanadhi | 66.9 | 18 | 1.0 | 19.0 | 31.8 | 21.8 | 53.6 | 77 | 2080 | 182 |
| Godavari | 110.5 | 38 | 6.9 | 44.9 | 45.8 | 30.7 | 76.6 | 21 | 345 | 171 |
| Krishna | 69.8 | 47 | 6.3 | 53.3 | 47.8 | 23.0 | 70.9 | 2 | 265 | 133 |
| Pennar | 6.3 | 5 | 1.3 | 6.3 | 6.3 | 5.3 | 11.6 | 26 | 300 | 1821 |
| Cauvery | 21.4 | 18 | 5.8 | 23.8 | 19.9 | 15.1 | 35.0 | 11 | 160 | 47 |
CASE STUDY OF BIHAR
Bihar, a state situated in the eastern part of India, will serve and apt case to illustrate various issues and aspects related to interlinking of rivers. In the envisaged national scheme of interlinking of rivers, Bihar occurs significantly, probably as a water surplus region.
The present day Bihar, after a separate state of Jharkand, can be considered as comprising two distinct hydrological regions, North Bihar lying north of the river Ganga up to its border with Nepal and South Bihar lying south of Ganga adjoining Jharkand. While most of Bihar is part of the Ganga basin, north Bihar is drained by rivers originating in the Himalayas and Nepal, and south Bihar is drained by rivers originating in the Vindhyan, Chhotanagpur and Rajmahal hills. All these rivrs join Ganga at various confluence points lying mostly in Bihar.
The fact that rivers of north Bihar cause recurrent floods, ie; they carry more water than they can contain within their banks and hence it is concluded that if this excess flow is transferred to a water deficit river/basin, it will not only provide valuable water to serve its needs but would also solve the problem of floods in north Bihar. For this, each component of the view is dealt with separately as follows.
RECURRENCE OF FLOODS AS CONCLUSIVE EVIDENCE OF SURPLUS
In the case of north Bihar, recurrent sccurences of floods are caused by a combination of the following five factors,
(i) Hydrometeorological
The catchment areas of north Bihar rivers receive almost 85% of their annual precipitation during 4 months of the south-west monsoons during June-September, mostly concentrated during July and August. The annual precipitation varies from 130 cm in the North Bihar plains up to 300 cm on the southward slopes of the Himalayan part of the catchments in Nepal.
(ii) Hydrological
On an average, more than 60% (85% in the case of Kosi and 76% in the case of Gandak) of the aggregate catchments areas of north Bihar Rivers lie in high precipitation region outside north Bihar, mostly in Nepal.
(iii) Topographical
Catchments of north Bihar rivers undergo a very large and sharp change in gradients from very steep in the mountainous (Mt. Everest lies in these catchments) to steep in the sub-mountainous parts to extremely mild in the north Bihar plains through a relatively short stretch of 300 Km.
(iv) Hydraulic
When high flows resulting from run-off transformation of seasonally concentrated precipitation in higher precipitation upper catchments areas travel from steep gradients and encounter mild gradients downstream, they exceed the conveyance capacities of rivers in their lower reaches. So they spill over the banks and inundate the flood plains, using them as temporary dynamic storage.
(v) Demographic
as the inundated flood plains support habitation, agriculture and other activities of a high-density population, floods cause recurrent disruption, damages and devastations on a large, attractin national attention. Recurrent floods in north Bihar constitute a case of ill management of water resources rather than being an indication of water being in surplus on an annual and basin wide scale. This is also linked by other facts and situations as mentioned below,
(a) It is common experience that crops damaged by floods at one time suffer from agricultural drought subsequently. In Bihar, it is estimated that agricultural droughts cause 25% less in crop yields.
(b) About 30% of cultivable land in north Bihar is presently under irrigation, while 90% of the cultivable land is irrigable. When this high potential irrigation is provided, agricultural water demand will rise considerably.
As per the “Report of second Bihar state irrigation” commission(1994) , irrigation water demands will fall short of availability of water in the state to meet food grain requirements of the rising population by the year 2025.
(c) When India and Nepal will agree to co-operate in developing their shared water resources comprehensively, not only will north Bihar rivers be free from recurring floods, but other beneficial uses of water- consumptive as well as non-consumptive such as for irrigation, hydro-power generation, water transport, industrial as well as municipal uses and aquaculture will also be secured for immense mutual benefits. In that case, the perception of north Bihar rivers being water surplus will undergo a fundamental and conceptual change.
ENVIRONMENTAL, ECOLOGICAL AND HUMAN IMPACT
As interlinking of rivers is achieved by a combination of engineering measures such as dams, barrages, cross drainage structures and link channels, environmental and ecological impacts as well as displacement of people resulting form each of them will be the consequences of interlinking.
The link channels of interlinking system will be different from natural or other man made channels in the following ways along with their associated consequences. The purpose of a link channel is conveyance and transfer of water, as distinct from a natural channel, which is for drainage or irrigation channel which is for distribution of water or a navigation channel where basically depths are maintained for plying of boats. Link channels will mostly be in filling to avoid excessive lift, will have to cross natural drainage channels and may pass through forested or inhabited areas. These channels will generally carry high discharges requiring large cross sections, and hence these factors will lead to the following consequences.
(1) Unless the link channels are lined, which will be a cost-prohibitive proposition, will cause heavy seepage which will not only constitute loss of water under transfer but may also create water logging conditions in certain areas.
(2) They are likely to cause substantial displacement of people giving rise to problems of resettlement and rehabilitation. As the people to be displaced will be far from being beneficiaries, there is bound to be resistance on their part.
(3) As these long link channels may pass through dense forest and habitats of wildlife, their ecological consequences may be serious and substantive.
(4) Import of vast amount of water in arid or semi-arid areas may adversely affect their dry land ecology.
EXISTING INTER BASIN TRANSFER PROJECTS
The periyar Project, Parambikulam Aliyar Projet, Kurnool-Cudappah Canal and the Telugu Ganga Project in the south and inter sub-basin transfers in the Indus basin and Rajasthan canal project in the north are good examples of inter basin water transfers executed in India in 19th and 20th centuries.
The Periyar project
A masonry gravity dam 47.28m high has been constructed across a gorge on west flowing Periyar river. A1,740m long tunnel with a discharging capacity of 40.75m3/s has been driven across the mountain barrier to convey the waters eastwards to Vaigai basin. The project was commissioned in 1895 and provided irrigation to 57,923ha initially, which has since been extended to 81,069ha. There is also a power station of 140 MW capacity.
Rajasthan canal project
The project diverts water from the Himalayas to the deserts of Rajasthan. The projet comprises of a huge multipurpose project constructed across the Beas river at Pong, a barrage at Harike and a grand canal system.
ABROAD
(i) In United States, the California’s state water project, first phase of which was completed in 1973, provides for the diversion of 4 cubic Km of flow from better watered northern California to the drier central and southern parts of the state. The conveyance system comprises of 715 Km long California aquaducts a complec system of lined and unlined canals, pumping stations, siphons and tunnels. The lift involved is nearly 1,000m.
(ii) Inter basin transfer projects have also been planned and implemented in China and former USSR. A notable scheme executed in the USSR is Irtysh Karaganda scheme in the central Kazakistan. The link canal is about 450 Km long with a maximum capacity of 75 cumecs. Lift involved is 14 to 22 m. other proposals include partial redistribution of water resources of northern rivers and lakes of European part to the Caspian sea basin involving 2 M.ha-m of water.
(iii) In china recently completed inter basin transfer include Biliuha-Daliah inter basin water supply system, trans basin transfer of Luhana river to Tiajian river and Tengshan. Diversion of yellow river surpluses and south to north transfer project.
Promises | Pitfalls |
| Transfer 173 billion cubic metres of water to water-stressed regions | More inter state water disputes; Diplomatic row with Bangladesh &Nepal |
| Building 11000km of canal network | Increased incidence of water logging and submergence of 79,292 ha of forests. |
| Generate 34000 MW of power | Rising funds a constraint; cost-overturn to make the project prohibitively costly. |
| Boost GDP growth by 4% | 4.5 lakh people to be displaced. |
The foreign schemes give confidence for planning inter-basin water transfer schemes in India. At the same time, lessons have to be learnt from their actual performance, economic viability and environmental suitability.
The envisaged benefits to water-deficit regions of the country through interlinking of rivers and also solution for problems such as flood as seen from case study of Bihar should be assessed and analysed in terms of economic, environmental and ecological as well as social cost involved and finding options and alternatives in the context.
The conceptual, technological and economic aspects of interlinking need comprehensive examination and analysis.
