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
