Lesson from Chennai: Give back flood plains to rivers
The resilience of a city is gauged by its ability to bounce back quickly after a calamity. Chennai is back on its feet after the devastating cyclonic storm wreaked unparalleled havoc on it. But it still limps when it comes to evacuating people—thousands of them are still marooned by flood waters. However, the government’s coordinating efforts in distributing food to the stranded and restoring electricity and telecom lines are laudable. Most importantly, fatalities are far fewer than in the 2015 floods.
Past floods have left a trail of destruction along the waterways of Adyar, Cooum, Kosasthalaiyar, Buckingham Canal and Pallikaranai Marshland. After the 2015 floods, the stormwater drainage system in the city was enhanced with financial support from the World Bank and connected to the Adyar, Cooum, and Kosasthalaiyar rivers, which ultimately empty into the bay.
But they obviously cannot take in vast amounts of flood waters when the skies abruptly open up. Worse, their capacity has been compromised by fast-unfolding urbanisation. Indiscriminate construction across the city has also created obstacles for the natural flow of water. Chennai had already received good monsoon rains, leaving the groundwater levels healthy and blocking substantial absorption of flood water.
In 2015, an artificial flood was created by the release of a huge amount of water overnight from the Chembarambakkam lake. This year, the government was cautious and released water in small quantities to avoid flooding the river banks. The rainfall this year was much more than in 2015, with Chennai receiving 43 cm in Meenambakkam and 44 cm in Perungudi on December 4. Further, the cyclone, which hovered on and near the city for a while, made it difficult for the rivers to empty into the bay.
A parliamentary standing committee report after the 2015 floods blamed the real estate mafia for illegal constructions and the grabbing of water bodies and flood channels. The Flood Plain Zoning, a concept initiated by the state public works department then to regulate land use in flood plains, is gathering dust.
Apparently, there is no data on the flood plain of Cooum or Adyar, and the boundaries of these rivers are yet to be marked. The government ought to take a serious look at urbanisation gobbling up large parts of flood plains and river beds, and initiate a sincere effort to retrieve them.