Groundwater fails to replenish expanding concrete jungle

THANE/MUMBAI: A state department’s groundwater survey has found that the number of areas in the Konkan region seeing a drop in water levels has increased nearly seven-fold since 2015. While 629 areas or villages in Konkan witnessed a drop of up to 1 mt this year, the corresponding number was 95 mt in 2015 when the state faced a water crisis due to weak rainfall the previous year.
Forty one areas registered a drop in Thane district, while 163 areas in Raigad and 176 in Palghar registered water depletion of up to 1-metre levels. For the first time, the lush Konkan belt has seen this rapid depletion of water stock, which even if under 1m, could be a cause of worry, said experts.

Geologist Amar Joshisaid the rate of success for borewells in Mumbai has been decreasing every year, with nearly half of the efforts failing to strike water.

The Maharashtra Groundwater Act permits digging up to 200 feet but people have dug up to 800 feet in Mumbai and not got water. “I recently visited one site in western suburbs and found one borewell 600 feet deep and another 800 feet—and both had no water,” said Joshi.

Officials attribute the drop to poor rainfall this year and excessive draining of the stock from the underground aquifers (natural reservoirs). Borewells are dug because of residential and farming needs, but indiscriminate digging can lead to faster depletion of the underground stock. “Water percolation in the ground requires a steady pattern of rainfall as just heavy rains don’t necessarily mean good percolation. The rains, even of a light drizzle, have to last a long period for optimum percolation which wasn’t seen this year,” said an official from the ground water supply department from Pune. The dropping levels could be an indication of excessive suction of water, he added. Rampant urbanisation and concretisation had worsened the situation.

Joshi said, “With large parts of the city being concretised, where and how will the recharge of water take place? Mumbai being an island, the rising salt water will contaminate the whole soil, making it saline.” BMC officials say they dissuade people from digging below 25-30 metres for borewells because the water tunnels in the city run 50 metres deep. “As a precautionary measure digging for borewells that deep is not allowed ,” an official said.