'Failure to protect lakes may prove costly for City'

Failure to protect lakes from rampant encroachment may cost dear for the City, according to experts.

The disappearance of lakes due to encroachment is one of the main reasons for the depletion of groundwater in the City. Though the Bangalore Water Supply and Sewerage Board has been supplying piped water to the City, the officials of the Board say that the City would turn into a desert if attempts were not made to preserve water bodies.

Dr Ritu Kakkar, Director General,  Environmental Management and Policy Research Institute (EMPRI), said that lakes were store houses of water and they act as recharge pits.

‘Rapid urbanisation’
“But, rapid urbanisation has closed down the inlet drains of the lakes resulting in the slow death of lakes. The City is slowly turning into a concrete jungle with no space for percolation of water.

The rainwater, instead being allowed to be stored in lakes, is flowing onto roads leading to flooding. The existing lakes are also drying and slowly disappearing due to encroachments,” she added. 

Echoing a similar view, K C Subhash Chandra, former geologist, Department of Mines and Geology, said, “Rainwater does not infiltrate into the ground if enough silt has not accumulated in the lake. But again, Bengaluru has a massive hard rock structure and studies have shown that only three per cent of the rainwater actually gets infiltrated into the ground.”

Huge mismatch
He said that there was a vast difference in the amount of water extracted from the ground and the recharge of groundwater.

“There is large-scale exploitation of groundwater as borewells are extracting four times more than the water that is recharged. People have exhausted dynamic groundwater resources and are in the process of drying up even the static water resources,” he added.

An official from Bangalore Water Supply and Sewerage Board  said that although the City receives over 800 mm of rainfall annually, the permeability of rainwater percolating the ground is just around 20 to 60 cm per year.

Therefore, the amount of water that is extracted through borewells cannot be completely recharged.