With the south-west monsoon still being active over the region and the State, the time, as the north-east monsoon too is expected to bring a good amount of rain, is ripe for undertaking rainwater harvesting in the region, said an expert.
Chairman of Marine Geology Department with Mangalore University Hejmady Gangadhar Bhat said that not much water can be harvested or saved for future when the south-west monsoon is in full swing. The groundwater table will be high during the period.
As the south-west monsoon loses its vigour, the groundwater table too begins to reduce and it will be the right time to recharge when it continues to rain till December, Prof. Bhat said. The coastal area receives up to 4,000 mm rainfall in a year and saving little portions of it comes in handy during the summer, he noted.
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Giving the example of Narayana Rao, a farmer in Pilar village, off Padubidri in Udupi district, Prof. Bhat said that rainwater that is collected on his three-acre plot is not allowed to escape. Mr. Rao has dug trenches in his farm to harvest rainwater and recharge his open well and borewells. Consequently, he gets water from his wells at a depth of just 7 ft, he noted.
Another farmer, V.J. Cutinho, a retired police sub-inspector, who is undertaking farming activities at Konnepadavu village near Moodbidri, has successfully installed rainwater harvesting mechanism for a bore-well in his farmland and is getting a good yield, Prof. Bhat said.
As per his suggestion, Mr. Cutinho dug up a trench of 10 ft by 10 ft by 10 ft around the borewell, filled it with river pebbles, sand and mesh to harvest rainwater, he said.
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While a centimetre of rain on 1,000 sq ft surface can yield 2,500 litres of water, all the rain during the season on a similar surface can yield up to 3.24 lakh litres of water. Even if portions of such rainwater are harvested or diverted to underground sumps, they can help reduce dependence on external sources of water, Prof. Bhat noted.