Bengaluru has a ‘concrete’ plan for erratic weather
But to digress, even the shortest spell of rain is a nightmare for people residing in the low-lying areas or next to storm water drains — the thundershower the city received late on Sunday being a case in point.
A large number of families live in the fear of water gushing into their little homes, destroying all that comes on its way.
Experts suggest, instead of more concrete structures, the authorities should focus on non-structural solutions as much as they do with structural measures to mitigate climate change-triggered flooding.
So, what are non-structural solutions?
They include a minimum of 60 mm rainwater harvesting facility in each of the 20 lakh buildings in
The two aforementioned solutions – if implemented in large-scale – can stop about 80% of the rainwater flowing into the rajakaluves and prevent flooding in the low-lying areas, according to conservation experts BM spoke to.
This is absolutely possible as the municipal corporation alone has an annual budget of over Rs 1,000 crore just for improving storm water drains.
Incentivising families providing rainwater harvesting facilities, as experts point out, is one of the ways to encourage a large population in the city to conserve water.
Rainwater as resource
Dr Srinivasa Reddy, former director of
According to Reddy, structural measures such as re-modelling and de-silting can only increase the carrying capacity of the drains. “Some parts of the city flood even when the rainfall is as low as 10 to 20 mm. This is the extent of concretisation that has happened with no space for the water to drain out or recharge into the ground,” Reddy explained.
S Vishwanath, founder of
A 6,000 litre water tank or 20-ft deep sump, he said, is sufficient to store water received from a 60-mm rainfall. “These facilities already exist in a majority of the buildings. What the government needs to do is encourage people to harvest rainwater through incentives and mass campaigns,” he noted.
Each building should ensure a minimum of 60 mm rainfall does not leave its plot. Water should either be harvested or stored. They will save a lot of money and stop flooding
– S Vishwanath, Rainwater Club
Vishwanath was not happy with the way the roads and shoulder drains are designed. “Both roads and drains need to be integrated. What we are seeing is the worst form of engineering. The water does not flow into the drain at all,” he said.
He suggested creating two to five feet deep rings inside the drains so that the water can percolate. Another suggestion given by the water expert is the use of open places including large parks such as
Leo Saldanha, co-ordinator at
“Irrigation tanks – now called lakes – are a technology that is almost 6,000 years old, dating back to pre-Vedic Harappan times when people figured out how to harvest rainwater and surface runoff to sustain farming through non-monsoon periods. This sustained hundreds of urban centres. The very same idea continued down the centuries to our times, where lakes and their canals (rajakaluves) harvest rainwater,
The civic bodies, he said, have allowed pollution and encroachment of these water networks. “In their stupidity, they concretise canals and ring-bund lakes, leaving no space for water which floods our tarred and concretised roads and built areas destroying lives, livelihoods and property. It’s truly necessary to become smart and rely on age old wisdom to let the water stay, flow and nurture life. Not cause death and destruction,” he said.
So far, the Bruhat Bengaluru Mahanagara Palike (BBMP) has spent around Rs 2,000 crore to build concrete retaining walls on a 389-km network of storm water drains. Similar work is currently underway along a 75-km network. In addition, the civic body has engaged a contractor to de-silt 400-km of drainage paying Rs 31 crore a year.
Additional chief secretary,