Land and water resources of India

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 5000 glaciers cover about 43000 km2 in the Himalayas with a total volume of locked water estimated at 3870 km3. considering that about 10000 km2 of the Himalayan glacier is located within India, 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.

The total surface flow, including regenerating flow from ground water and the flow from neighbouring countries is estimated at 1869 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 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 and 1105.6 km3/year to Bangladesh (“Irrigation in Aisa in Figures”, Food and Agricultural Organisation of the United Nations, Rome, 1999; http://www.fao.org/ag/agL/public.stm). For further information, one may also check the web-site “Earth Trends” http://elearthtrends.wri.org.