Guest column: Bengaluru’s lakes need scientific planning, not cosmetic changes
How were lakes created in the city?
It is imperative to understand why lakes were created in Bengaluru before we discuss rejuvenation of lakes. At the heart of reviving lakes lies the maintenance of storm water drains (SWD).
Most of the lakes in the city are manmade and were created by building a bund across the water flowing down, while in the low-lying areas bunds were built so that water could be impounded. Hence, not only the quality of water becomes important but the quantity is equally a serious issue. In situations where villages are built down the lakes, the water bodies play an important role in mitigating floods.
Reason for worsening condition of the lakes
The latest (or even the past) Detailed Project Report (DPR) prepared by BBMP’s technical committee shows that neither the hydrological study of the catchment area nor the water impounding capacity of the lakes have been restored to their original state, creating a backflow in many lakes.
The inlets in many lakes are at a much lower level than the lake bed and there is a reverse flow of water from the lake into the inlet in several lakes.
The lack of coordination between the UGD, SWD, groundwater and the lakes departments is exhibited in the way lakes are rejuvenated. While this is the story of the government-based rejuvenations, the CSR based rejuvenations are mostly fund based rather than need based. When the rejuvenation is fund-based, mostly, the scientific part of the rejuvenation is ignored and this pulls us back to square one situation.
When the foundational principles of hydrology, limnology, civil engineering and environmental engineering are being ignored, fund inflow will serve no purpose as it was seen in several cases that without any planning lakes were selected and later on sewage started entering the lake.
Knowing the amount of water flow from the catchment areas with regard to rainfall and sewage is a must, and most of the DPRs do not take both the hydrological studies.
While the concentration should be more on water chemistry and biology the present narrative is more of beautification. The part of the DPR that takes only recreation and beautification into account reek of elitist mentality.
If groundwater needs to be properly recharged then desilting becomes an important part. The narrative that there is no need for desilting falls flat.
Integrated water management policy
It is crucial for lake rejuvenation to work in tandem with the integrated water management policy. Lakes have to be seen as a source of water for ground water recharge or of direct use of treated water for construction.
Lake health index and sustainability index need to be followed with all the parameters and with due respect given to ecological aspects rather than cosmetic changes.
