Visuals of people being rescued from flooded upmarket colonies and slums on tractors/trucks/coracles; submerged roads, and luxury cars sunk to their bonnets, in parts of India’s Silicon Valley, Bengaluru, have put ill-planned urban expansion on the centrestage again. The plight may continue with the Indian Meteorological Department saying more rains could be in store.
Urban planning experts blame the swallowing of crucial drainage links, lakes, and other water bodies, because of unrestrained construction for Bengaluru’s plight. Rainbow Drive, one of the upscale localities, suffering from the worst of the floods, for instance, is built on an area that once served as an important link between three lakes. Similarly, KR Puram, another flood-hit area of the city, has seen significant construction in areas that formed parts of the drainage network for the KR Puram lake.
In 2015, a 11-member committee chaired by long-time Karnataka legislator KB Koliwad reported that close to 11,000 acres of lake land had been encroached upon by construction, by real-estate developers and the government itself! Indeed, the Bengaluru Development Authority admitted some years ago, in the context of the demolition of houses near the Puttenahalli lake in the city, that it had approved 23 layouts (areas earmarked for real estate development) on tank beds.
Earlier this year, a study based on satellite images of 42 prominent lakes in Bengaluru, by researchers at the BMS Institute of Technology and Management, found 450 acres of surrounding wetlands lost to encroachment between 2000 and 2019, much after the Koliwad report had flagged the problem as rampant across the city. Forty-one of the 42 lakes had seen an average reduction of 10.33% in their physical areas. Between 1800 and now, the number of lakes in the city have fallen from over 1,400 to close to 200.
The Bruhat Bengaluru Mahanagar Palike has said that the Bellandur and Varthur lakes overflowing is primarily responsible for the worst of the flooding in the city. The BMSITM study had reported that these lakes had lost the highest quantum of land to encroachment. While the government has is making rejuvenation efforts for both lakes, it has to consider rejuvenation of the channels that drain into and away from lakes, creating a network.
A seminal factor behind the flooding is also the construction across valleys that has obstructed the drainage of water from the higher parts of the city to the Dakshina Pinakini and Kaveri rivers through seasonal streams, says Raj Bhagat P, senior programme manager (geo-analytics) with the World Resources Institute. “There has been a drastic change of the topography due to construction of buildings and roads, and the existing channels have don’t have the capacity to carry water during days of heavy rain,” he says.
Adding to poor urban planning are climate change effects that are unfolding sooner than expected. A 2020 study titled Climate Change Scenario in Karnataka: A Detailed Parametric Assessment, by the Karanataka State Natural Disaster Monitoring Centre, found average annual rainfall in Bengaluru Urban district rose from 836 mm (1960-1990) to 943 mm (1991-2017). While warning of “long spells of little to no rainfall between heavy rainfall events”, the report says that for south interior Karnataka, where Bengaluru lies, the monthly mean rainy days have increased in most of the months in the 1991-2017 period.
Indeed, the World Bank, in its 2021 climate profile for India, says large swathes of Karnataka (including Bengaluru) could see the change in the maximum five-day rainfall accelerate upwards in the next few decades compared with a baseline of 1986-2005.