BENGALURU: As per records, Agara Lake is spread across 142.73 acres. But in reality, the lake’s area has shrunk by 36.43 acres because of encroachment. Buildings have been constructed in the buffer and even within the lake boundary. Not just that, untreated sewage continues to flow into the lake -- situated in the Koramangala- Challaghatta valley in southeast Bengaluru, while a large area of the lake is covered with macrophyte.
The water body, which is managed by the Lake Development Authority, falls under E Category (as per Central Pollution Control Board norms), meaning its water is not fit for consumption. It can only be used for irrigation, industrial cooling and controlled water disposal. This is not the only lake in the city that has been encroached. Similar is the case with Ulsoor Lake and Sankey Tank, to name a few.
These are some of the findings uploaded on the Bangalore Lakes Information System (BLIS) portal created by researchers from the Energy and Wetlands Research Group, Centre for Ecological Sciences, IISc. The portal was launched on a trial basis four months ago and since then, 2,728 citizens have viewed the website, downloaded and utilised the data. “But none of them are government agencies or officials. This is similar to the Bangalore Urban Information System portal which was launched on January 22, 2024. The documents uploaded on BLIS have been compiled by extensive field research, using remote sensing technology and government base maps,” said Prof TV Ramachandra from CES, IISc.
The report -- Bangalore Lakes Information System (BLIS) for Sustainable Management, was also published as a journal and released on Friday (October 25, 2024). The researchers have assessed 175 lakes in the city since 2013 and noted that 92% of them are encroached. The portal provides geo-visualisation of information about lakes in Hebbal-Nagavara, Koramangala-Challaghatta and Vrishabhavathi watersheds of Bengaluru, till 2023.
Temporal land use reveals that Bengaluru’s landscape has transitioned from a porous landscape (with 68% vegetation cover, 274 lakes/wetlands, and less than 8% built-up area) to a paved contiguous surface (less than 3% vegetation cover, 193 lakes, 86% paved surface) with the loss of vegetation cover (88%) and water cover (79%). Unplanned developmental activities post-2000s, due to concentrated construction for IT parks and Special Economic Zones in the city, have given impetus to rapid urbanisation with drastic and unrealistic land use changes. This has led to decline in the groundwater table, causing urban flooding, stated the report.
The BLIS is designed with information on water quality, biodiversity (microalgae, zooplankton, ichthyofauna, macrophytes, and birds), threats (encroachments, inflow of untreated sewage, etc.) and ecosystem services of lakes in Bengaluru. The portal and report empower decision-making through knowledge of lake distribution in terms of physical, chemical and biological aspects and the value of ecosystem services, which is crucial for evolving strategies for prudent management of water bodies in Greater Bengaluru, he said.
