Rainwater harvesting: India
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Harvesting rain woes for summer redemption BANGALORE: Two years ago, most houses in the low-lying pockets of Rankanagar , near Hebbal , had turned into islets because of heavy rain, leading to waterlogging and inundation of the area. But come summer, Rankanagar tends to die of thirst. While the Cauvery water supply system has become a farce, the groundwater table has hit new lows and dried up borewells. Soaring tempers in the area could have ignited protests in front of the BWSSB and BBMP offices this time. But it hasn’t , thanks to a local initiative that has fixed both problems in a way the two civic agencies couldn’t even have dreamt of. Things had gone horribly wrong for Rankanagar two years ago. Its groundwater table had dried up and water wasn’t available in borewells even after digging 800-1 ,000 feet deep. Trapped between the seasonal vagaries of swirling rainwater and depleting groundwater resources , residents, led by Rankanagar and Neighbourhood Residents’ Welfare Association , saw the answer in BWSSB’s mandatory rainwater harvesting campaign. They dug 13 rainwater harvesting wells linking the roadside drains, killing two problems with one stroke. Waterlogging during rainy season has virtually been eliminated, while the dying borewells have sprung back to life this summer.
“The rainwater harvesting wells were designed by us with help from IISc scientists in 2010. Pulakeshi Nagar MLA Prasanna Kumar helped us and the financial aspect was taken care of. Now, we have 13 such wells in roadside storm water drains. Not a drop of water fallen in this locality goes waste,” asserts MM Naazim, secretary of the association.
The wells have been designed in such way that they trap rainwater flowing on the drains. The muck, if any, is filtered in the well because it has four different layers of filtration processes installed. Apart from metallic grills, the wells have perforated slabs of sand layer, jelly stones and grill mesh and slopes down towards the pit. The 80-foot-deep wells are laid with concrete rings.
“We have surveyed the locality inch by inch. We understood the flow of rainwater as per the drainage network and fixed 13 appropriate places for the wells. It’s the most environmentalfriendly practice and prevents soil erosion. Besides, it is low cost and easy to manage ,” said G Dev Prasad, vicepresident of the association.
“In 2005, when we were first supplied with Cauvery water, I used to get water once in three days and I’d consume 40,000 litres every month. But now supply is on alternative days, but I draw only 6,000 litres. The only way to manage the crisis is to harvest rain. Besides the community approach, individual bungalows too harvest rainwater,” said Vaziruddin M, president of the association.