One of the starkest reflections of Bangalore's water crisis is in the frenetic proliferation of borewells, both private and public, panning the city from its central business district to its very margins. Indeed, the gap in water supply, of 250 mld (million litres a day), is now met by tapping a natural resource that is being depleted faster than it can be replenished — groundwater.
According to the BWSSB's own estimates, there are no fewer than 1,10,000 private borewells in the city that either supplement, or meet completely, the water needs of households across the city. As for public borewells, the BWSSB has drilled 7,272 so far, a figure that is set to increase considerably this year, according to officials.
And counting…
In response to the intensifying scarcity, BWSSB sunk close to 450 borewells in the first four months of the year alone, and is gearing up to drill another 450 by the end of the year, T. Venkatraju, Chief Engineer (Maintenance), BWSSB, told The Hindu . When added together, the annual figure (of 900) obtained is nearly three times higher than the number of borewells drilled in the previous two years (January 2008 to November 2009): 346.
And needless to say, the water-table has plummeted to an all-time low. Water is now struck at a depth of between 800 ft to 1,000 ft, particularly in the East Zone (including K.R. Puram and Mahadevpura) and the North Zone (Yelahanka and Byatrayanpura), said Mr. Venkatraju.
Routine water-table evaluations by the Department of Mines and Geology corroborate this trend. Of the 47 borewells and dug wells sampled by the department in February 2010, the water level in as many as 42 had decreased since 2009; only four had increased and three had dried completely.
Lakes have a role
More worryingly, the city's lakes — the primary source through which groundwater is recharged — are being allowed to languish, says T.V. Ramachandra, professor at the Centre for Ecological Sciences at the Indian Institute of Science. A research paper co-authored by Dr. Ramachandra illustrates this correlation between the loss of wetlands and the depletion of groundwater in the vicinity.
In the last 35 years, unfettered urbanisation has cost Greater Bangalore 60.8 per cent of its lakes, found the study which has recorded a startling decrease in the depth of the ground water table from 10 -12 mt to 100-200 mt.
The ambitious lake rejuvenation project taken up by the BDA and BBMP would do well to consider the role of lakes in groundwater recharge, says S. Vishwanath, an expert on rainwater harvesting. He suspects whoever that the project views lakes merely as a “water storage facility.”
