A saying in Kannada, commonly cited by advocates of rainwater harvesting, including Shree Padre, goes like this: “Oduva neerannu hariyuvante madi, hariyuva neerannu tevaluvante madi, tevaluva neerannu ingisi” (Make gushing water flow, make flowing water crawl and make crawling water percolate into the soil).
Even in some areas in Dakshina Kannada and Udupi districts, which are at a higher level, groundwater was available at a depth of 180 ft a few years ago. Now, it has gone down to 400 ft, according to E. Shekarappa, Senior Geologist (Groundwater Section), Department of Mines and Geology, Dakshina Kannada Zilla Panchayat
Although groundwater gets recharged during the rainy season, the storage gets depleted in some areas by January, owing to overexploitation.
N.J. Devaraja Reddy, hydro-geologist and rainwater harvesting consultant based in Chitradurga, said that excessive groundwater use would weaken the rock strata. It would give scope for percolation of saltwater from the sea to the fresh water zone.
“Once saltwater enters the rock strata, it will be difficult to replace it,” Mr. Reddy said.
Mr. Reddy said that it was time people of the coastal belt took to rainwater harvesting, discarding the old belief that the present rainfall would be enough to meet their current and future water needs. Underground aquifers might go dry unless recharged, he warned.
Mr. Reddy, who is a member of Karnataka State Water Resources Authority, suggests various methods for replenishing groundwater, including recharging borewells and open wells with rainwater, creating percolation pits at the foothills of hilly areas, and rejuvenation of old lakes and tanks.
Check-dam
Chairman of Alva's Education Foundation M. Mohan Alva said that the foundation last September built a check-dam across a stream at Umigundi, near Moodbidri, for recharging groundwater, at a cost of Rs. 80 lakh. The foundation purchased a five-acre plot for the purpose. As a result, the water-table in a radius of 5 to 6 km around the dam did not diminish during this summer.
All open wells in the surrounding areas were full this year, he said.
Mr. Alva said that the foundation had recharged three borewells on its campus at Vidyagiri, using rainwater a year ago.
Modus operandi
According to Mr. Reddy, there are over 20 methods of recharging borewells some of which are suitable for the coastal belt.
Mr. Reddy said that the roof should be kept clean before collecting rainwater through pipes. Water from roof should be diverted to a borewell only through a sand-bed filter.
He said that if there are open wells, water from the roof filtered through a sand-bed filter could be diverted to them too.
It is still not too late to go in for rainwater harvesting since the rains are still a month away.
Mr. Reddy of Geo Rainwater Board, Chitradurga, can be contacted on phone 9448125498 (e-mail: devraj05@gmail.com). Mr. Padre can be contacted on 04998-266148 (e-mail: shreepadre@gmail.com).
