Efficacy of coastal reservoirs to address India’s water shortage by impounding excess river flood waters near the coast

Abstract

India is a sub-continent where presently 320 million people remain in the water-starved parts of the country and according to the UN, this number is expected to increase to 840 million in the year 2050. There is a severe demand-supply mismatch. Though there has been no significant change in India’s rainfall pattern, the number of areas under drought in India is increasing every year. Increase in population is one of the reasons for water scarcity but the inefficient management of the received precipitation stands as the major cause. Though extreme rainfall events are significantly increasing, there is a spatial non-uniformity in the rainfall events that occur. This makes it difficult to pre-plan large scale water storage at different locations. Out of the 4,000 billion m 3 of freshwater available from precipitation per annum, major portion run off into the sea. The solution to India’s water problem is to conserve the abundant monsoon water bounty, store it in coastal reservoirs, and use this water in areas which have occasional inadequate rainfall or are known to be drought-prone or in those times of the year when water supplies become scarce. It is estimated that about 4,400 thousand million cubic feet of rainwater just simply drains into the sea. This paper focuses on the concept of Coastal Reservoir. This basically means building a storage structure near the mouth of river. In this way, the amount of water that is wasted as run-off can be stored. The construction of a coastal reservoir does not involve many risk factors and disadvantages like relocation which would occur in an inland dam construction. The paper also presents the concept of Sarovarmala - a chain of coastal reservoirs which is an innovative concept that has the potential to ensure water availability to India throughout the year.