When lakes vanish, water tables dip

DNA / Subir Ghosh / Wednesday, March 21, 2012 

The term “water woes” has today become a cliché. But it’s not water supply issues or the associated woes that are disturbing. What is, is the fact that water has been disappearing right from under our noses. Bulk of the water supplied to Bangalore has to be carried from afar because there’s precious little groundwater left.

Najeeb KM, regional director of the south-western zone of the Central Ground Water Board (CGWB) offers a pointer as an explanation: “One of the prime reasons groundwater tables have been falling drastically, particularly in the peripheral areas of the city, is the rapid disintegration of lakes. As lakes keep either drying up or being converted for ‘development’ purposes, the water tables are bound to dip.”

The consensus among experts is that the groundwater tables are falling mostly in peripheral areas. “The water table is falling precipitously all along the periphery of thecity where the Bangalore Water Supply and Sewerage Board (BWSSB) network does not exist, but is rising in the city centre, thanks mainly due to leaking pipes,” says Vishwanath of the Biome Environmental Trust, an NGO that works on water-related issues.

Ramachandra Mohan, professor, Bangalore University, goes further and links lakes to watertables. “Lakes are like kidneys of the ground. They filter the unwanted matter and seep in only the necessary clean water into the ground. But, the number of lakes have gone down in recent years. Groundwater tables have gone down to 1,000 feet. Although there is a enough rain in the city and in the state, there is no place to store it. Lakes have become very shallow too. The number of lakes have decreased as well.”

The relation between lakes and water tables is no mere theory. A case in point is the Puttenahalli Lake which was revived through citizens’ intervention a few years back.

The Chairperson of the Puttenahalli Neighbourhood Lake Improvement Trust, Usha Rajagopalan, points out that the groundwater levels in the area have definitely improved. “The increase in number of birds present in the lake is another indicator. At the same time, evaporation has caused the surface level to drop a bit. We are hopeful that soon the 200-odd trees that we have planted around the periphery will reduce the rate of evaporation and the Puttenahalli lake would be full of water even in summer. We are also trying to divert more rainwater into the lake,” says Rajagopalan.

If the number of trucks streaming out of the area is any indication, borewells here are working once again. Says Rajagopalan, “The borewell operators in the area are definitely aware how the restoration of the lake has recharged the water table. I am not very sure if the more educated and economically better-off see the connection, since their supply of bottled water is still intact.The importance of lakes, not only in relation to recharging the water tables, but in so many other ways cannot be underestimated.”

Mohan takes the issue further and predicts a disaster. “We are heading towards a major drought if we don’t take immediate action. In Bangalore, there was a time when we could find water at 25-30ft. Where is that now? This is because, we are not replenishing lakes and have no water sinking areas. Lakes are very important to the city. That’s it.”

Rajagopalan saves the last word as one of advice, “It is in people's own interest to protect lakes/tanks – as much as villagers in the past took care of ponds. Our education and lifestyles have distanced us from nature. We need to take corrective steps urgently so that our children do not suffer because of our callous indifference to nature and to waterbodies in particular.”

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