In the past 15 years, India has seen several episodes of extreme rainfall in 24 hours: Mumbai received over 900mm of rain in 2005, Chennai had over 300mm in 2015, and now Bengaluru saw over 130mm. As climate change intensifies, we face the gloomy prospect of failure by governments, society and citizens across the world to limit the warming to 1.5°C above pre-industrial times.
Higher rates of evaporation from oceans, seas and land are pumping larger amounts of water vapour into the atmosphere in shorter periods of time. A warmer atmosphere is able to hold more water vapour, and this has led to an increase in heavy downpours. Further, with the warming of the Arabian Sea, cyclonic storms that were earlier largely associated with the Bay of Bengal and the eastern coast are now impacting cities and settlements on the western coast. In the coming decades, such extreme rain events are likely to increase.
Bengaluru had several advantages compared to many other Indian cities: a high elevation, an undulating topography, interconnected lakes, green spaces that helped soak rain, and rajakaluves (storm-water drains) that helped convey excess runoff. Most of these natural as well as human made advantages have been squandered away, both legally and illegally, exacerbating the city’s risk and vulnerability to floods.
