Chennai harvests only 10 percent of its rainfall

Chennai: With the city receiving an incredible amount of rainfall over the last couple of weeks, rain water harvesting experts suggest that Chennai could do a bit more than just diverting them into drains.

Dr Sekar Raghavan of the Rain Centre tells DC that as much as 60 per cent of the city’s rain water could be harvested, against the current rate of less than 10 per cent. Raghavan, who noted that harvesting was site and soil specific, said that Chennai’s coastal areas were underutilised when it came to harvesting rain water. “Because sandy soil is great in trapping rainfall,” he said.

The current arrangement where Metro Water and Chennai Corporation together empties almost the entirety of rain water into drains, sewers, canals, rivers and then back into the Bay of Bengal, was a situation that could be avoided, Raghavan said. “The core city’s storm water drain network is already levelled in such a way that it empties into the nearest nullah, so retrofitting these drains to form a network that empties into a harvest site may be difficult. But with smart city ideas being bandied about, it is time that the administration looks at implementing a sustainable model of harvesting,” he said.

To this effect, Sekar explains how the Rain Centre had made suggestions, around six months earlier, to the CMDA in altering the rules regarding rain water harvesting. “CMDA was a little naive when RWH rules were introduced in 2003. They thought a one size fits all system was enough,” he said.

Replacing the mandatory requirement of recharge pits to recharge wells, Sekar said, for plans including a set-back area must be introduced. He added that another suggestion whereby schools, colleges, government office and corporate buildings with large campuses should be mandated to interrupt the storm water drain in front of their built up area and lead it into a harvest site established within their campus.

Though Sekar lamented that the state, just like any other, had sacrificed sustainability in the name of development, he said that at least Tamil Nadu still remained a role model in rain water harvesting.

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