Abstract

India is the fifth largest country in terms of area in the world. It has 3.288 million sq. km. The first four largest countries are: Russia (17.075 m.sq.km); the USA (9.629 m.sq.km); China (9.597 m.sq.km); and Brazil (8.512 m.sq.km). Population wise, India ranks second in the world. As on 18.08.2019 India’s population is 1365.3 million and World population is 7676.6 million (indiastat.com). That is, India has 17.8% of the world population. As far as Tamil Nadu is concerned, its population in 2011 was 72.14 million and it increased to 81.20 million in 2019. As far as the world water resources is concerned, the 29% of land area has one lakh KM3 of fresh water, in which about 60% goes as evaporation annually. The remaining 40%, i.e. 40,000 KM3 goes as run-off by rivers and percolation to groundwater in the world. India’s share is 4% of world supply that is 4000 KM3 . It is estimated in India, 51% of precipitation goes as evaporation and the remaining 49% is the annual water resources that is 1953 KM3 . This is divided as 1521 KM3 (78%) as surface water and 432 KM3 (22%) as groundwater resource. From this quantum, the annual utilizable water is calculated as 1086 KM3 (690 KM3 as surface water and 396 KM3 as groundwater). However, the present quantity of water use is only 600 KM3 from both surface and groundwater resources. This is only 31% of annual water resources (for details see chart 1). If, available quantity is prudently used India can solve many water related problems.

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