There are four sources of surface water – river, lake, dams and tanks. Out of these, rivers are the main. The estimated annual water flow in all river basins is 1869 cubic m. Due to topography, water flow speed and other reasons, only near about 690 cubic m (32%) part is used by local people.
Ganga, Brahmaputra and Indus rivers are spread on almost one – third part of total area, which provide 60% water of the total surface water resources, while the rivers of central India (Narmada, Tapti and Mahanadi) provide 16% of total surface water resources and the rivers of south India (Godavari, Krishna and Kaveri) provide the remaining 24% surface water.
