What are the major sources of surface water?

Explanation

There are four major sources of surface water. These are rivers, lakes, ponds, and tanks. In the country, there are about 10,360 rivers and their tributaries longer than 1.6 km each. The mean annual flow in all the river basins in India is estimated to be 1,869 cubic km. rate. Due to topographical, hydrological and other constraints, only about 690 cubic km (32 per cent) of the available surface water can be utilised. Water flow in a river depends on size of its catchment area or river basin and rainfall within its catchment area. Precipitation in India has spatio temporal variation, and it is mainly concentrated in Monsoon season. Some of the rivers in the country like the Ganga, Brahmaputra, and the Indus have huge catchment areas. Precipitation is high in the catchment areas of the Ganga, the Brahmaputra and the Barak rivers, these rivers, although account for only about one-third of the total area in the country, have 60 per cent of the total surface water resources. A good percentage of water flow in south Indian rivers like the Godavari, the Krishna, and the Kaveri has been harnessed. The other sources of surface water like lakes, ponds and tanks are utilized. In south India, tank irrigation is common.