Water, which sustains life on earth, is an invaluable natural resource. Earth is the only planet in the entire solar system which supports life, because it contains water. About 71 per cent of the surface of the earth is covered with water, but only about 3 per cent of the total water on the earth is freshwater.
i. We made use of freshwater for domestic purposes, irrigation, agriculture, industries and transport.
ii. Even the small amount of freshwater is not available in the same quantity everywhere.
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iii. There is surplus water at one place and shortage at the other.
iv. Nearly 70 per cent of the freshwater occurs as ice sheets and glaciers in Antarctica, Greenland and in the mountainous regions of the world.
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Water Resources of India:
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India has only about 4 per cent of the world’s water resources. The main sources of water are precipitation, surface water and groundwater.
The total water received from precipitation is not available for use, as much of it is lost by evaporation and a good deal of it goes as run-off to rivers, lakes and ponds. A small amount seeps through the soil to form groundwater.
i. The surface water is available to us in the form of rivers, lakes, ponds and other water bodies.
ii. Rivers are the most important source of surface water in our country.
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iii. The mean annual flow of Indian rivers is about 1900 billion cubic metres. Out of this only about one-third of this can be utilized.
iv. The total flow of all rivers of India is about 6 per cent of the discharge of all rivers in the world.
v. The effective storage capacity of surface water in India is only about 150 billion cubic metres, which is only 8 per cent of the total flow of all the rivers.
vi Thus, about 92 per cent of the surface water flows into the sea.
The groundwater potential in India is about 450 billion cubic metres. Water percolates easily in the alluvial soils. Thus, the potential of groundwater development is high in the Northern Plains of India.
Of the total groundwater resources, about 25 per cent is used for domestic, industrial and related purpose, while 75 per cent is used for irrigation.
India is basically an agricultural country, where about 65 per cent of the total population is directly or indirectly dependent upon agriculture. In order to increase agricultural production, we have to improve our water supply system, i.e. irrigation system.