Can Bengaluru withstand another stormy monsoon?

If the summer rains of the last few days are anything to go by, Bengaluru may well have a stormy monsoon, literally speaking.

The Bruhat Bengaluru Mahanagara Palike’s grand plan of fixing the problem of flooding has not worked so far. Most lakes are already full and the stormwater drain (SWD) network is either incomplete or encroached upon. The rainy days are likely to damage homes and livelihoods.

Last year, the house of Siddalingaiah, a resident of Pramod Layout in Nayandahalli, was under six feet of water. He is worried the situation will be no different this year. “The BBMP is yet to complete the remaining work of building the retaining walls. I fear the problem will only worsen because water that flows for several kilometres ends up in our area,” he said.

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The BBMP claims the city cannot handle more than 70 mm per hour of rainfall. “We had close to 210 flood-prone areas in the city. The number has been brought down to 96 by undertaking various interventions, including regular desilting of rajakaluves and building side drains. Our lakes and drains do not have enough space to carry or store water if there is heavy rain,” a senior BBMP official said.

At the same time, officials cite political interference for their inability to do much on clearing drain encroachments. As per the BBMP’s own data, close to 630 buildings have encroached on the drains.

Recharge wells

Experts bet big on building at least a million recharge wells in the city to tackle the twin problems of recharging groundwater and minimising the chances of flooding.

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An Indian Institute of Science (IISc) report, entitled ‘Urban Floods: Case Study of Bangalore’ by Prof T V Ramachandra and Pradeep Mujumdar, highlighted how recharge wells should be provided in the catchment area of critical flood zones to detain floodwaters.

Some areas such as Malleswaram, Jayanagar and Koramangala already have such recharge wells but the BBMP has not scaled them up in a big way. “Recharge wells have the potential to eliminate flooding. It has been done in Lalbagh and Cubbon Park. Such wells should be built in all parks first,” said S Vishwanath, a water conservation expert.

“Our stormwater drains are not designed for 60 mm per hour intensity of rainfall. Besides building recharge wells, every building must be responsible for collecting and recharging rainwater. A small site can harvest one lakh litres of rainwater. Many are already doing it. More people must start implementing rainwater harvesting facilities,” he said.