ABSTRACT
As per the observations taken by the Indian Meteorological Department at more than 3000 rainfall-recording stations for a period of 50 years (19011950) the average rainfall is 105 centimeters. It is the largest in the world for a country of comparable size. From precipitation alone India receives 4000 Km3, including snowfall. Of this 3/4th occurs only during the monsoon. A good part of it is lost through the process of evaporation and plant transpiration, leaving only half of it on the land for use. After allowing for evapotranspiration losses the country’s surface flow is estimated as 1880 Km3 (CWC 2000). Due to topographical, hydrological and other constraints, it is assessed that only about 700 Km3 of surface water can be put to any beneficial use by conventional methods of development. The annual replenishable groundwater resources are assessed to be about 600 Km3 of which the annual usable resources are estimated at 420 Km3 (CWC 2000). Since Independence, the country has been planning to utilize this water by prolonging its stay on land by using engineering innovations such as dams and barrages.
