'Rejuvenation efforts turn fatal for lakes in the City'

Researchers from the Department of Environment Sciences (DES), Bangalore University (BU), stated that mere water preservation is not healthy; instead, the urban lakes should be declared biodiversity hot spots.

BBMP has plans to rejuvenate over 30 lakes; but, the researchers observed that the rejuvenation process will actually reduce the lakes to water bowls which eventually lose their significance.

The researchers pointed out that using heavy machinery to expedite the rejuvenation works is crude and unscientific and it would endanger both the aquatic and wildlife depending on the lakes.

M Sunil Kumar, a City-based environmentalist, said, "They are basically trying to convert lakes into swimming pools."

He said, Herohalli lake on Magadi Road was buzzing with rich bird diversity and water after the rains. The lake was drained when the desilting works began and also has been shrinked in size as a jogging track is being constructed by filling up a portion of the lake, he added.

A survey conducted as part of their research by the DES revealed that the plight of other water bodies was no different after the rejuvenation works.

According to Aboud Jumba, a researcher studying City lakes under Dr S Nandini, Chairman and Head of the Department, DES, most of the practices adopted in the rejuvenation focus mostly on how to maximize rain water harvesting.

He said, these wetlands are not just water bowls. They comprise a complete aquatic ecology which is in a balanced rhythm with the surrounding environment.

Database on wetland

"There is a need to create a database on the wetland types, morphological, hydrological and biodiversity data, surrounding land use, hydro geology, surface water quality, and socio-economic dependence," he said.

The rejuvenation work taken up without considering these aspects will be harmful to natural bio-remediation and will adversely affect water conservation in the long run.  
Dr  S Nandini said, "The rejenuvation of the lakes should be done on a case-to-case basis. All lakes are not alike. It is wrong to treat them through one lens of engineering techniques. An Environment Impact Assessment should be done by studying them properly."

Biodiversity Act

Emphasising role of the public in rejuvenation efforts, the study advocates a buffer zone be established between the wetlands borderline and a development zone.
"Even the channels that link up lakes should be protected and shielded from daily discharge of untreated sewage," said Dr Nandini.

Their study recommended that all the wetlands should be brought under the Biodiversity Act which lays stringent guidelines to protect the lakes.

The study also observed disilting may be necessary for removing contaminated sediments of lake's floor. But this should be limited to only those lakes which are gravely contaminated or ecologically speaking-dead lakes.

"Desiltation contains a grave risk of exacerbating hydrological imbalances between the surface water basin and the ground water table. Sediments on lake's floor play an important part as a hydrological filter and valve that manages the local surface and sub-surface water cycle,” the study stated.