In water… Without water
Water, water everywhere /nor any drop to drink…’ these lines from The Rime of the Ancient Mariner by Samuel Taylor Coleridge define the Indian Islands. Wondering why? Read on…
The Indian islands comprise of the Andaman and Nicobar Islands in the Bay of Bengal, and Lakshadweep Islands in the Arabian Islands. In spite of being surrounded by water, water is a major problem in these union territories. Let’s take a trip of both the groups of islands one after the other.
Andaman and Nicobar Islands
Andaman and Nicobar Islands are a group of 321 northsouth running islands. Andaman group covers 6,346 sq km, and Nicobar group covers 1,953 sq km. This archipelago gets an average annual rainfall of 3,000mm. But, most of the rain water is lost as surface runoff due to the island’s rugged physiography (physical features).
The soil cannot retain water, as it is composed of clay and sand. The soil has to be rich in sand and gravel to provide high permeability, which is necessary for constructing groundwater-harvesting structures like dugwells.
Drops of wisdom
Since ages, the tribes in the different islands followed different methods of harvesting rain and groundwater. Here are few examples:
In the lower southern part of the Great Nicobar Island, the Shompen tribals made bunds using logs of hard bullet wood. For irrigating crops, they direct the flow of rains to the fields situated at lower elevations by digging channels.
The Shompen and Jarawa tribals use bamboo to direct water to shallow pits called Jackwells, built in increasing order of sizes
Unfortunately, most of the traditional water harvesting systems have been neglected and are in a bad state. For instance, the Dilthawan tank, built by the British to provide water during the construction of the infamous Cellular Jail, is languishing due to excess silt that has reduced its storage capacity. Though the local government tried to revive the traditional water harvesting systems in the late 1980s, it is now promoting drilled borewells in the new colonies.
Lakshadweep is known as the coral paradise of India. It is a group of 36 islands, out of which only 11 are inhabited. The total area is only 32 sq km. It receives good rainfall, the annual average being 1,600mm. Then, how can there be water shortage?
The problem is that there are no forests and vegetation. The topography is almost flat, and the surface soil is composed of coral sand that is barren in most islands. In some islands like Bitra, the groundwater is saline due to sea ingresses. The islands only have sand dune ridges formed by the accretion (accumulation) of coral debris, which is highly porous. Due to this, there is no stream or interior drainage.
Drinkable freshwater comes from a layer of groundwater formed within 0.5-1.5m (carbonate sand layer). Tidal fluctuation of the sea, shortage of rainfall and excessive withdrawal from the wells often lead to its depletion and salt-water intrusions.
Drops of hope
But, there is always a way out. The islanders know the importance of water conservation, and have moulded their lifestyle accordingly. For drinking water, they use wells and stepwells. These wells are generally lined on the top half and unlined on the bottom half, where boulders or bricks are stacked to enable free flow. Some stepwells, ponds or tanks are also used for washing and bathing. Almost every household has a dugwell for domestic purposes. Groundwater is drawn using bucket and rope. And every mosque here has a pond attached to it. The government has also taken some steps to build rain water-harvesting structures in the islands to ensure the supply of safe drinking water.
Revival: the only getaway
At present, the main problem is that the demand for water in these groups of islands is rising with expanding tourism. The unique physiography, culture and vegetation crash the modern alternatives. Revival, protection and development of the traditional groundwater and rainwater harvesting systems are the only suitable options available. And the original inhabitants are the best guides.