Thirsty islands

Islands in the Bay of Bengal have to contend with increasing scarcity of fresh water

 
By Kailash
Published: Monday 31 March 1997

THE islands in the Bay of Bengal are facing a shortage of fresh water almost every summer. Despite the abundant sea water and more than 3,000 mm rainfall in the region, many of the islands are unable to store the fresh water.

The availability of water has been affected by the rapidly growing population in different islands. There has been a nine-fold increase in the total population of the islands between 1951 to 1991 (from 3 1,000 to 278,000) - Andaman's population alone rose more than 12-fold from 19,000 to 241,000. In Andamans, there were only 61 villages in 1951. This increased to 137 in 1961 and 356 in 1991. All these villages came up after clearing virgin forests.

Rainfall, its harvesting and the water-retention capacity of the soil have come down because of the heavy population pressure on the physical landscape of the islands. In 1988, there was 3,365 mm of rainfall. In 1990, the figure was only 2,593 mm. Similarly, the number of rainy days reduced to 163 in 1990 from 199 in 1988. The summer of 1990 proved to be the starting point of a fresh crisis of domestic water in and around the capital, Port Blair. Besides, the continuous shrinking of forests has also reduced the surface water availability. The level of sub-surface water is also decreasing gradually.

On the other hand, the demand for water has increased in recent years because of continuing industrialisation, shipping activities, health services, setting up of more defence establishments and the hotel industry. At present, there are 363 industrial units in the Andamans. Of these, 315 are concentrated in South Andaman, especially in Port Blair.

The collection of water, its treatment and conservation have been neglected for many years. As an alternative, plenty of sea water can be utilised for drinking and other domestic uses if the technology to process it is available in the islands. Solar stills can be one method for desalination. This is suitable for small islands, which are not heavily populated. The stills consist of a glass chamber in which the sea water is boiled by the Sun's rays. The vapours are converted into fresh water after condensation. The sea water can also be processed through flash distillation. The heated saline water flows through a series of chambers, which are maintained at different atmospheric pressures. The water evaporates in each section of the chamber and the vapours get condensed. The distilled fresh water thus produced at each stage, is gathered either separately or collectively.

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