Although India has vast surface water resources same are not evenly distributed so far time and place are concerned. While some rivers are perennial others become dry or carry small quantity of water during dry season.
During monsoon months much of the water is wasted during floods and flows down to the sea but in dry months of the year there is scarcity of water. Also there is flood in one part of the country and droughts and famines in another part.
These problems can be minimised through inter-basin linkages or through national water grid under which water from one basin is transferred to another basin for utilization. This idea is not new because many such schemes are already under execution in the country.
The chief among these include: (a) the Periyar Diversion Scheme, (b) the Kurnool-Cuddapah Canal, (c) the Parambikulam- Aliyar Project, (d) the Indira Gandhi Canal, (e) the Beas-Satluj Link Canal, and (0 the diversion canal from Ramganga to the Ganga. The National Water Grid is just an extension of the concept on a larger scale.
Its salient features are as follows:
1. The Ganga-Kaveri Link Canal passing through the basins of the Son, Narmada, Tapi, Godavari, Krishna and Penner.
2. The Brahmaputra-Ganga link Canal passing through the state of Bangladesh.
3. The Narmada Canal passing through Gujarat and western Rajasthan.
4. The canal from the Chambal to central Rajasthan, and
5. The link canals between the rivers of the Western Ghats towards the east.
1. The Ganga-Kaveri Link Canal
At the request of the Government of India a United Nations team prepared a project report on a Ganga-Kaveri Link Canal. The main aims of the project are to safeguard against the recurring floods in the Ganga Basin and to assure more water to the comparatively less rainfall areas of central and eastern India. The scheme envisages the Ganga and the Kaveri to be linked by a man-made canal 2,635 km (1,650 miles) long, not only to provide water essential for human life but also to provide for sanitation, irrigation, power generation, navigation and flood control. This grand link canal will cost Rs. 28,750 million (1970 estimates) and if and when completed, the country will no longer have to depend so much on the monsoon, the vagaries of which are well-known (N.I.P., 19-8-1979, p. 9).
The scheme proposes to draw 1,700 cusecs (60,000 cusecs) of water from the Ganga construct
ing a barrage near Patna and lift it by large pumps to a point near the boundary of the basins of the Ganga and the Narmada from where it will be possible to distribute the water by gravity via dug-up canals or through existing rivers to the west or south.
The flood waters of the Narmada (flowing into the Arabian Sea) and the Godavari (flowing into the Bay of Bengal) could also be used profitably by a separate water gnd. Water for the inter-basin transfers would be derived from the Ganga only during the four months of the rainy season (July to October) when the flow exceeds on an average 2,850cumecs (1, 00,000 cusecs).
The length of the Ganga-Kaveri Link Canal will be between 2400-3200 km depending upon the actual alignment finally chosen, with smaller secondary branches connecting areas chronically prone to drought. It is also proposed to supply the Ganga waters (about 290 cusecs or 10,000 cusecs) to Bihar, Uttar Pradesh, Jharkhand, Chhattisgarh and Madhya Pradesh by pumping additional water during the lean water season there.
Similarly 1,410 cusecs (50,000 cusecs) of water pumped for 150 days or more depending upon the surplus waters in the Ganga would be diverted during the high flow period only and would be transferred outside the basin to meet partially the water demand of the chronically drought prone areas of Rajasthan, Gujarat, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka and Tamil Nadu.
A point near Patna will be the starting point of the link canal, at a height of 45.7 m above the sea level which would collect the surplus water from the Ganga. From here the water would be pumped into a series of reservoris between the water sheds of the Narmada and the Son involving a pumping lift of 335 to 400 m. From this elevated place (Bargi reservoir on the Narmada 423 m) a lined aqueduct will convey the water to the south utilising the natural water courses of the Wainganga, Pranhita and Godavari and crossing the Krishna and the Penner to the Kaveri River upstream of the Upper Anicut.
Storage would be provided enroute, especially on the ridge regions to conserve the water for the dry season. These storages would be located inside valleys, which do not have sufficient catchment area of their own, to provide adequate runoff and would be utilised during dry season.
On the way, water would also be released into the basins of the Narmada and the Tapi rivers which flow westward into the Arabian Sea and the Godavari, the Krishna, the Penner and the Kaveri which flow eastward. From selected points on the Son itself water pumped separately for the basin will be diverted to areas prone to drought in the Ganga basin also.
The project involves huge expenditure, massive survey operation and strong administrative decision. Since it will take even decade or more to complete the project and has several administrative, economic, social and ecological constraints the government has not yet taken any decision to execute it.