From garden city to concrete jungle: 78 percent of B'luru's surface is paved, IISc study finds
Each time Bengaluru receives mild to heavy showers, the city comes to a standstill — there are waterlogged roads, flooded neighbourhoods, traffic jams that get worse (if that is even possible), power cuts, falling trees and more.
It is ironic, sad even, how residents become anxious about rains in a state that has been reeling under severe drought for the past few years.
Rapid and uncontrolled urbanisation is one of the major factors responsible for the flooding.
According to a recent IISc study, 78% of Bengaluru's land surface is paved, and it is likely to go up to 94% by 2020 if the problem is not controlled.
Titled Frequent Floods in Bangalore: Causes and Remedial Measures, the study has been authored by TV Ramachandra (IISc), Vinay Shivamurthy (IISc) and Dr Bharath H Aithal (IIT-Kharagpur).
Between 1973 and 2017, the study states, the paved surface in the city has increased by a staggering 1028%. Increased concretisation leads to increased impermeable catchments (which restricts the flow of water), which results in flooding.
"Frequent flooding (since 2000, even during normal rainfall) in Bangalore is a consequence of the increase in impervious area with the high-density urban development in the catchment and loss of wetlands and vegetation," the study states.
A woman feeds her child in her water logged house following heavy rains, at Thanisandra in Bengaluru; PTI Photo by Shailendra Bhojak
This, coupled with other factors such as narrowing and concretising storm water drains, lack of appropriate drainage maintenance works, encroachment on floodplains, dumping construction and other solid waste blocks the flow of water.
The researchers, who found that several NGT guidelines had been violated, blame the aggravated situation on the "unplanned irresponsible urbanisation by senseless decision makers".
The study found that the rajakaluve (storm water drain), which connects Bellandur Lake from the City Market side has been narrowed to 28.5m against the original width of 60m, which is in violation of recent NGT guidelines.
Similarly, in Jakkasandra village, which is in the upstream of Bellandur Lake, the width of the rajakaluve has been reduced by nearly 50% between 1908 and 2017.
Speaking about how Bengaluru has become prone to floods, Dr TV Ramachandra had earlier told TNM that the BBMP's Rs 800 crore project to revive storm water drains is not a solution to the problem.
"Building concrete drains will not solve the issue. What we need is an eco-friendly system of drainage which will contribute to groundwater recharge. Dumped construction material and solid waste have blocked the system," he said.
"When you look at the maps of Bengaluru’s watershed management during the British era, it will baffle you. It was so well planned that the city could sustain heavy rain. The rampant encroachment of marshlands and buffer zones of lakes, obstruction of sewer pipes and manholes, encroachment of storm water pipes, garbage dumped in the SWDs have blocked the outlets of rainwater," he explained.
Some of the solutions offered by the researchers in the study are to re-establish interconnectivity among lakes by removing all blockades, protect valley zones and buffer regions of wetlands, stop narrowing and concretising natural drains and to decongest Bangalore.
Dwindling number of lakes
Intense and uncontrolled developmental activities have also drastically reduced the number of water bodies in the Bengaluru, which once prided itself for gaining the moniker 'land of lakes'.
The study says, "These lakes were all interconnected with canals/drains (kaluveys’s) to enable transferring excess water to the next lake. These lakes catered the basic needs such as maintaining and recharging ground water, drinking water to the surrounding people, habitat for fishes and other aquatic ecosystems, sustaining food (fish, etc.) and agricultural activities, etc."
Froth spills over from a polluted lake to the streets in Bengaluru; PTI Photo by Shailendra Bhojak
In the last four decades, there has been a 79% reduction in water bodies and lakes in the city, the study states. Worryingly, the number of lakes in Bengaluru has reduced from nearly 285 in the early '70s to 194 in 2006).
"Urbanisation during 1973 to 2017 (1028% concretization or increase of paved surface) has telling influence on the natural resources such as decline in green spaces (88% decline in vegetation), wetlands (79% decline), higher air pollutants and sharp decline in groundwater table," it adds.
Garden city no more
According to remote sensing data, there are only 1.5 million trees for Bengaluru's 9.5 million strong population which means there is one tree per seven persons. This, the study says, "is insufficient even to sequester respiratory carbon (ranges from 540-900 g per person per day)."
If this trend continues, Bengaluru could eventually turn into a "water scarce, non-resilient and unlivable" city.