The ongoing monsoon season has once again revealed how our cities crumble under heavy rains. The ill-equipped stormwater drainage network and failure to protect their natural ecosystem has left urban centers to pay a heavy price, Bengaluru being the latest example.
But, as the monsoon gets more erratic and extreme rainfall becomes more frequent due to climate change, booming cities could face dire consequences if they don’t take stock now, experts have warned. With several cities, including flood-hit Bangalore, yet to prepare their climate action plans, the delay, experts say, could cost them dearly.
“It’s hard to decide whether Bengaluru is witness to nature’s fury or a man-made disaster, but its devastating impact is there for all of us. Environmental and climate hazards have long been neglected in urban planning. and, despite such disasters, they have yet to be incorporated into our master plan,” says Lubaina Rangwala, Urban Development Program Manager at the World Resources Institute (WRI).
Until August 31, Bengaluru had received 33% excess rainfall in the current monsoon season, with southern interior Karnataka receiving rainfall up to 62% above its long-term average (LPA). But the monsoon unleashed its fury in early September, with Bengaluru recording its wettest monsoon in two decades. According to IMD, the computing hub recorded its third-highest 24-hour rainfall on September 4, after 1988 and 2014.
Climate change has already triggered an increase in the frequency of heavy rainfall events over the country. Short-lived rainfall extremes are intensifying and cities are collapsing because they cannot cope with even slightly above normal rainfall, let alone violent episodes.
Where is the diet?
As arbitrary construction and development progresses, an efficient and equipped stormwater drainage plan to handle rainfall is the critical missing link. While the issue is raised every year, little has been done on the ground. Experts denounce the short-sighted planning that has plagued most cities.
“We need to know our cities better and understand where and how we build buildings. All of this cannot be done without an appropriate roadmap. We need granular datasets of the entire stormwater drainage system and delineation of flood prone areas, which we haven’t done so far. All of this needs to be incorporated into the city’s master plan to regulate any future growth,” says Raj Bhagat Palanichamy, who worked on geo-analysis for sustainable cities at WRI.
As climate risks intensify, cities may be the first to face its devastating effects. Mumbai, Hyderabad, Ahmedabad, Bengaluru and several others already have a glimpse of extreme events that are expected to occur more frequently in the coming years. In its 2020 report, the Ministry of Earth Sciences highlighted how the increased frequency of localized and short-lived heavy rains have increased the risk of flooding in India, especially in urban areas.
Green gray infrastructure
“With all the delay that has already happened, we will now have to do so many things, and all at the same time,” says a dejected Rangwala, drawing attention to the urgent need to prioritize hybrid infrastructure and protect the natural ecosystem, open spaces and flood plains. “First we create a problem, then we look for ways to solve it, instead of avoiding it in the first place.”
As cities grew, wetlands, swamps, and floodplains that acted like natural sponges to absorb and slowly release excess surface water—helping to withstand extreme rainfall—have were the first to disappear. Precipitation needs a passage to run off and if the natural drainage system is blocked due to past development choices, cities will have to deal with the consequences.
“The monsoon provides 70% of the annual rainfall, and this rainwater literally flows through every major city. A well-designed drainage system that is closer to the natural topography of a city is what is needed. There are existing climate vulnerabilities that need to be taken into account. And all of this needs to be well planned and integrated into the master plan to build sustainable and climate resilient cities,” adds Rangwala.
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