Water management
Water resources
The two main sources of water in India are rainfall and the snowmelt of glaciers in the Himalayas. Although reliable data on snow cover in India are not available, it is estimated that some 5 000 glaciers cover about 43 000 km2 in the Himalayas with a total volume of locked water estimated at 3 870 km3. Considering that about 10 000 km² are located in Indian territory, the total water yield from snowmelt contributing to the river runoff in India may be of the order of 200 km3/year. Although snow and glaciers are poor producers of fresh water, they are good distributors as they yield at the time of need, in the hot season. Indeed, about 80 percent of the flow of rivers in India occurs during the four to five months of the southwest monsoon season.
The total surface flow, including regenerating flow from groundwater and the flow from neighbouring countries, is estimated at 1 869 km3/year, of which only 690 km3 are considered as utilizable in view of the constraints of the present technology for water storage and inter-state issues. A significant part (647.2 km3/year) of these estimated water resources comes from neighbouring countries: 210.2 km3/year from Nepal, 347 km3/year from China (Chinese data) and 90 km3/year from Bhutan. An important part of the surface water resources leaves the country before it reaches the sea: 20 km3/year to Myanmar, 181.37 km3/year to Pakistan (Pakistani information) and 1 105.6 km3/year to Bangladesh.
The Central Water Commission estimates the groundwater resources at 418.5 km3/year. Part of this amount, estimated at 380 km3/year, constitutes the base flow of the rivers. The total renewable water resources of India are therefore estimated at 1 907.8 km3/year.
Under the Indus Water Treaty (1960) between India and Pakistan, all the waters of the eastern rivers, i.e. the Sutlej, Beas and Ravi rivers taken together, shall be available for the unrestricted use of India. All the waters, while flowing in Pakistan, of any tributary which in its natural course joins the Sutlej main or the Ravi main after these rivers have crossed into Pakistan shall be available for the unrestricted use of Pakistan. This flow reserved by treaty is estimated at 11.1 km3/year.
India controls the flow of the Ganges River through a dam completed in 1974 at Farraka, 18 km from the border with Bangladesh. This dam was a source of tension between the two countries, with Bangladesh asserting that the dam held back too much water during the dry season and released too much water during monsoon rains. A treaty was signed in December 1996, under which Bangladesh is ensured a fair share of the flow reaching the dam during the dry season.
More information
(http://www.fao.org/nr/water/aquastat/countries/india/index.stm)