In this article we will discuss about the need for inter-basin water transfer in India.
India receives on an average about 4000 BCM of precipitation every year. More than half of this quantity is lost to the atmosphere or through deep percolation and only about 1869 BCM flow in the rivers as surface flow. Approximately 690 BCM of surface water and 432 BCM of groundwater are available for use per year through conventional water resources development strategies.
Nearly 60 per cent of the water potential lies in the Ganga-Brahmaputra-Meghna system in the north. Another 11 per cent in the high rainfall region of the Western Ghats flows through the small west-bound rivers draining into the Arabian Sea. Apart from sundry sources, this leaves barely 19 per cent from all the other rivers put together including mighty rivers like Mahanadi, Godavari, Krishna, and Cauvery which flow east through peninsular India towards the Bay of Bengal.
These large variations in water availability are the basis for the flood-drought-flood syndrome afflicting India with some areas suffering from flood damages, while some others battle acute long-run water shortage situations.
Availability of water for irrigation is thus critical to self-sufficiency in food grains. In-basin water resources development alone cannot increase the irrigated area beyond certain limits. The ultimate irrigation potential that can be achieved from in-basin development is estimated to be around 140 M ha.
But, for achieving the food production level of about 450-500 M t, it is imperative that an irrigation potential of at least 130 M ha for food crops alone and 160 M ha for all crops is created. One of the major strategies for achieving such a massive increase in irrigation potential could be inter-basin transfer of water.
With the view to develop water resources, the Ministry of Water Resources, formulated National Perspective Plan (NPP) in 1990. It comprises two components: Peninsular Rivers Development component with 16 river links and Himalayan Rivers Development component with 14 river links.
Peninsular Rivers Development Component:
It is planned to transfer around 141 km3 per year through peninsular rivers development component for redistribution within peninsular India. River links and proposed dams are given in Table 2.12.
Himalayan Rivers Development Component:
It is planned to transfer around 33 km3 per year through Himalayan rivers development component essentially for redistribution in Ganga basin and western India. River links and proposed dams are given in Table 2.13.
Although, huge amount of surplus water is available in the Brahmaputra and Bramhmini- Baitarni basins, since major parts of these rivers flow at an elevation lower than the Ganga basin, only a small volume of water can be transferred from the Brahmaputra basin.
If the volume of water to be transferred through the proposed links is added to the resources already available, we get a healthy picture of about 1660 km3 per year of developed water resources for the country that can take care of any exigencies.