11th August, 2003
RIVERS
INDEPENDECE DAY FEATURE


INTERLINKING OF RIVERS IN INDIA

Suresh P. Prabhu *


Long-distance inter-basin transfer of water has been in practice in India for over five centuries. The Periyar Project, Parambikulam-Aliyar Project, Kurnool-Cudappah Canal and the Telugu-Ganga Project are some of the examples of inter-basin water transfers executed in south India in the 19th and 20th centuries. The Periyar Project is the most notable endeavour of the last century in trans-basin diversion. A 47.28 metre high gravity dam was constructed across a gorge on the west-flowing Periyar river. A 1740 metre long tunnel with a discharge capacity of 40.75 cubic metres was drilled across the mountain barrier to convey the waters eastwards to the Vaigai basin. The project was commissioned in 1895 and provided irrigation to 58 thousand hectares initially. This has since been extended to 81 thousand hectares. There is also a power station of 140 MW capacity. The Parambikulam-Aliyar Project is a complex multi-basin multipurpose project. Seven streams-five flowing westward and two towards the east- have been dammed and their reservoirs interlinked by tunnels. The water is ultimately delivered to the drought-prone areas in the Coimbatore district of Tamil Nadu and the Chittur area of Kerala. The project has a command area of 1.62 lakh hectares with 185 MW of power generation capacity. The Kurnool-Cuddappah canal is 304 km long with a capacity of 84.9 cubic metres extending from the Krishna to the Pennar basin for irrigating an area of 53 thousand hectares of land. The Telugu-Ganga Project brings the Krishna waters from the Srisailam reservoir through an open canal to Somasila reservoir in the Pennar valley. From Somasila the water is taken through a 45 km long canal. By agreement among the riparian States 12 thousand metric cubic metres (TMC) of water will be delivered to Tamil Nadu to increase the water supply to Chennai.

Similarly in Himachal Pradesh, inter sub-basin transfers in the Indus basin and the Rajasthan Canal are some of the projects executed in the 19th and 20th centuries. A diversion dam, Pandoh, 140 km upstream of Pong on the Beas river enables the diversion of its water to the Bhakra reservoir and generates 165 MW of power on the way. The Beas-Sutlej link is 37.25 km long. Of this, 25.45 km passes in tunnel through difficult rock formations. The Rajasthan Canal Project diverts water from the Himalayas to the deserts of Rajasthan. The project comprises of a huge multipurpose project constructed across the Beas river at Pong, a barrage at Harike and a grand canal system. Executed both in the southern and northern parts of our country these projects have been highly beneficial and have not caused any noticeable environmental damage.

The USA, which is water-rich and scarcely populated, is transferring 45 billion cubic metres(BCM) of water through inter-basin transfer and plans to add 376 BCM. In Canada the existing schemes are designed to transfer 268 BCM. In comparison, India is transferring 10 BCM through the existing schemes and has plans to add about 200 BCM. China has a scheme under implementation which will transfer about 45 BCM. This indicates that India is already late in implementing the water transfer links.

Present Proposals

In India 30 links have been identified as technically feasible and economically viable on the basis of pre-feasibility studies. These are: Mahanadi (Manibhadra – Godavari (Dowlaiswaram) link, Godavari (Inchampalli Low Dam) – Krishna link, Godavari (Inchampalli) – Krishna (Nagarjunasagar) link, Godavari (Polavaram) – Krishna (Vijayawada) link, Krishna (Almatti) – Pennar link, Krishna (Srisailam)- Pennar link, Krishna (Nagarjunasagar) – Pennar (Somasila) link, Pennar (Somasila) –Cauvery (Grand Anicut) link, Cauvery (Kattalsi)- Vaigai-Gundar link, Ken-Belwa link, Parbati-Kalisindh-Chambal link, Par-Tapti-Narmada link, Damanganga-Pinjal link, Bedti-Varda link, Netravati-Hemavati link and Pamba-Achankovil-Vaippar link.

Similarly, based on various water balance studies carried out for the Himalayan component, the link proposals identified for preparation of feasibility reports include the Manas-Sankosh-Tista-Ganga link, Kosi-Ghagra link, Ghagra-Yamuna link, Sarda-Yamuna link, Yamuna-Rajasthan link, Rajastan-Sabarmati link, Chunar-Sone Barrage link, Sone Dam – Southern Tributaries of Ganga link, Ganga-Damodar-Subernarekha link, Subernarekha-Mahanadi link, Kosi-Mechi link, Farakka-Sunderbans link, and Jogigopa-Tista-Farakka link.

Benefits

Interlinking of rivers in India is expected to greatly reduce the regional imbalance in the availability of water in different river basins. Surplus water which flows waste to the sea would be fruitfully utilized. It is assessed that the inter-linking of rivers will provide additional irrigation benefits to 35 million hectares (Mha) -25 Mha from surface water and an additional 10 Mha from increased ground water recharge- which will be over and above the ultimate irrigation potential of 140 Mha envisaged from the conventional irrigation projects.

Construction of storage dams as proposed will considerably reduce the severity of floods and the resultant damages. The flood peaks are estimated to reduce by about 20 to 30 per cent in the Ganga and Brahmaputra basins.

The benefits of drought mitigation from inter-basin water transfers will accrue to an area of about 25 lakh hectares in West Bengal, Bihar, Jharkhand, Uttar Pradesh, Haryana, Rajasthan, Madhya Pradesh, Gujarat, Andhra Pradesh, Karnataka and Tamil Nadu.

Hydro power could also be generated on a massive scale by the storage dams proposed under the interlinking of rivers. Hydro power development has not kept pace with the potential and requirement in our country. Against a potential of 84,000 MW, only about 22,000 MW capacity for hydro power generation has been developed so far. For an efficient working of electrical energy generating system, the mix of thermal to hydro should be about 60:40. In our country it is about 75:25. The storage dams proposed under interlinking of rivers will greatly improve this situation. The total hydro power potential of the interlinking systems is estimated to be 34,000 MW.

Most of the mega cities and urban centres in our country are already suffering from water shortages. Many of the metropolitan cities depend upon long-distance inter-basin transfer of water for their domestic and industrial water supply. Delhi gets parts of its water supplies from the Ganga and Sutlej, while Mumbai gets water from Vaitama and Batsai, over 100 km away. Water supply in Chennai is being increased from Srisailam on the Krishna river which is 500 km away. A major part of the future requirements of big cities will have to be met from long-distance inter-basin transfer of water. In the link proposals under study, water supply to Mumbai and Delhi and many other villages and habitations enroute the link canals are proposed to be raised.

Perspective

India, with its geographical area of 329 million hectares but consisting of only 2.45 per cent of the earth’s land mass, supports a population of about 1027 million as per the 2001 census. This is about 16 per cent of the global population. The renewable fresh water resources of India at 1869 billion cubic metres (BCM) per year is only about 4 per cent of the earth’s fresh water resources. Thus average Indian has hardly one-sixth of land and one-fourth of water as compared to the world average. In view of the severe disparity in regard to water and land, its optimal use is essential to ensure a comfortable living for the people of India.

There are more inequities in the distribution of the water resources. The total renewable water resources as of the year 2001 correspond to about 1820 kilo litres (KL) of water per person per year. The population of India is expected to stabilize at around 1500-1800 million by 2050 when the per capita availability of water would further come down to nearly 60 per cent of the availability as in 2001. At that time, the per capita availability in the Brahmaputra basin would still be around 9000 KL and in the Sabarmati basin below 200 KL. This is against the minimum requirement of 1000 KL per person per year.

In view of the large variations in rainfall over space and time, the country experiences frequent floods in some parts and severe droughts in some others. Floods are a recurring feature particularly in the Brahmaputra and Ganga rivers which carry 60 per cent of the water resources of our country. Flood damages, which were of the order of Rs. 52 crore in 1953, went up to Rs. 5846 crore in 1998 with an annual average of Rs. 1343 crore, affecting Assam, Bihar, West Bengal and Uttar Pradesh besides causing untold human sufferings. On the other hand, large areas in Rajasthan, Gujarat, Andhra Pradesh, Karnataka and Tamil Nadu face recurring droughts.

It is expected that by 2050, India would need about 450 million tonnes of foodgrains. In order to attain this target, it would be necessary to increase the irrigation potential under all-food crops by 2050.

Most of the link canals will be 50 to 100 metres wide and more than 6 metres deep. That would greatly facilitate inland navigation from the north to down south. A boost to fresh water fisheries is also expected as a result of the programme. Apart from these benefits, guaranteed minimum flows in the rivers will enhance ecology and environment.

* Chairman, Task Force on Interlinking of Rivers

 

 
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