It is amazing that despite some of the best developed metros along the coasts of our country a big chunk of population living there has to struggle for every drop of water. Drinking water crisis is at peak. How our ancestors revered a natural resource like water and a broad overview of the coastal region to analyze the problem and solution thereof has been dealt with in the following narrative. Much of the problem is a self inflicted misery.
During the Vedic period natural resources like water were treated with reverence. The Vedas are full of hymns paying homage to the natural forces like fire, water and air. Hymns were sung in praise of the rivers, calling them divine. It is but natural that when so much was the respect for water that polluting a water-body sea was out of question. Industrial and technological development and ever increasing population this sacred natural resource has come under tremendous pressure.
Over 25% of the population of the Country lives along the 6000-km long coast. Fishing, sea-trade and other marine activities have been drawing the masses since times immemorial to live in the coastal areas.
The trade and industrial development along the coastal region in the past five decades has drawn more and more people Thus demand for water has increased tremendously in these areas. Increased demand leads to overexploitation of ground water and excessive drawl makes the seawater to creep into the fresh water reservoirs in the sub-surface. The seawater has a higher density and on reaching the ground water reservoir it sinks to the bottom. Consequently hitherto fresh water yielding tube-wells start yielding saline water. The problem is so acute that even in a developed metro like Chennai people in the heart of the city are forced to drink saline water. Fresh water is available only as bottled water.
Our eastern coast is made of alluvium and the western coast is rocky. In alluvial tracts sub-surface or ground water occurs in the pore spaces between the grains of sand. This film of water moves depending upon several physical parameters. Under normal circumstances the amount of water withdrawn is recharged by rainfall. In case the withdrawal of ground water is more than the recharge the strata underground collapse. This is due to the fact that the film of water, which holds the entire column of sand grains, is removed completely. It collapses like a roof without walls to support it. But alas water trade is so lucrative that the farmers in the vicinity of Chennai draw water from their tube-wells, and sell it to private tankers which ferry water for the urbanites. Farmer makes an average of Rs.15,000 per month in this deal. With electricity being free why should he bother to till his fields! Once the tube-well dries, he mines even the sand. Perhaps one of the worst examples of human apathy!
The sea on three sides encircles Indian mainland and our territorial water covers an area of 0.13 Sq. km. The western coast is 800 km longer than the eastern coast. The western coast of the Country especially in Gujarat and Maharashtra is industrially and agriculturally well developed. Areas close to the ports of Mangrol, Chorwad and Veraval show a tremendous increase in the withdrawal of groundwater. In Saurashtra area of Gujarat, the western coastal tract is about 15 km wide. Rocky ridges run parallel to the coast at a distance of about 100 to 200m. In such types of terrain rain or river water is unable to penetrate the ground. It is lost as a run off or evaporated. Consequently the marshes along the coast are more saline. In their greed to encroach upon as much as possible, humans do not spare even the marshes along the urbanized coasts. The human interference helps the salinity to reach the subsurface and thereby reach the reservoirs of fresh water. Providing drinking water to such settlements whether legal or illegal become responsibility of the State. Tube-wells in overpopulated coastal tracts produce saline water and the population blames the State.
The coastal tract of the eastern part of the Country stretches from Tamilnadu to Bengal. As compared to the West, the East Coast is much wider and has more sandy expanses. Major river deltas like; Cauvery, Krishna, Mahanadi, and Hooghly-Bhagirathi are developed on the eastern coast. The sandy or alluvial expanse is best developed in the Baitarni'Mahanadi delta system. It tapers towards Chilka lake region.
The Central Ground water Board (CGWB) has carried out extensive studies of the groundwater potential along our coasts. In a recent publication it has been highlighted that incursion of saline water in the Baitarni, Brahmani and Mahanadi basins extends upstream up to 20 to 60km. Due to availability of vast alluvial expanse, agriculture is a major occupation. It is but natural that more and more water is drawn for irrigation of fields. The over draft is resulting in to concentration of salinity. Along the coast of West Bengal, sea is in a regressive phase. In other words due to withdrawal of the sea more land is exposed. Saline water travels inland along estuaries and pollutes the fresh water basins.
It is important that all the fresh water bearing subsurface horizons are systematically evaluated and the amount of water available is estimated. The supply from the tube-wells has then to be regulated accordingly. Excess drawl of subsurface water is bound to create salinity problem. These salts upon reaching the surface make the soil also infertile. Thereby affecting the entire mass of humanity settled there. With the technology available it is feasible to adopt measures to recharge the aquifers with fresh water etc. As already said the excessive drawl can lead to land subsidence. This phenomenon is common in developed countries as well. Along the coast of Osaka Bay, Japan, due to over pumping of groundwater land subsidence to the tune of 1.8 to 3.1 meters has taken place in a span of 27 years. The residents of New York's Long Island faced the same problem. However, they were able to tide over it by artificially recharging the subsurface fresh water zones with water coming out of cooling towers of the air-conditioning plants.
Proper management of groundwater resource is quite a complex subject. Indiscriminate pumping and unauthorized sinking of tube-wells should be controlled first. A strict action by the Government and a pro-active role by the society are the only answers to the self-inflicted misery. In case we care for the future generation we have to rise above self. Else the poem of Samuel Taylor Coleridge, 'Water, water everywhere, Nor any drop to drink' would hold true for the population of our coasts.