A new study by the Centre for Ecological Sciences (CES) at the Indian Institute of Science reveals that by the end of this decade, Bengaluru’s dwindling water bodies could shrink to half their original number and expanse. By 2020, lakes will constitute just 0.74 percent of the city, which is around half their 1972 status when they made up 3.4 percent of the geographical area. Today, lakes constitute 0.9 per cent of Bengaluru’s area.

The study, ‘Ecological Insights to Mitigate Urban Flood Risks’, warns of a possible increase in the frequency and intensity of urban floods as lakes and their catchments are concretised. By the end of the decade, the city’s total built-up area will increase from the present 48 percent to 70.64 per cent. The co-author, T.V. Ramachandra from CES, said that this dramatic decline in the city’s water bodies is anticipated even though researchers added a projected 10-km buffer to the city’s present radius, including several more lakes.

The report also suggests that urbanisation has already made the city prone to floods. The interconnectivities between natural drainage channels are lost, and the city’s naturally undulating terrain altered, reducing water storage capacity and causing floods even during normal rainfall. Even a 30 mm rainfall in a matter of 30 minutes can now lead to floods, it says. While catchments are used as dump yards for municipal waste and building debris, lakebeds are now sites for multi-storey buildings that interfere with the natural catchment flow. An earlier survey by the team found that 54 per cent of the lakes were encroached upon.