Kerala Agricultural University has developed demonstration models of low-cost rainwater harvesting and storage systems that can be adopted by farmers to tide over the summer months when waterbodies dry up.

The 25-acre campus of the Agricultural Research Station under the university at Anakkayam in Malappuram district is fully equipped for high-tech horticultural nursery production utilising harvested rainwater in lined ponds. The Aromatic and Medicinal Plants Research Station at Odakkali in Ernakulam district has demonstrated the feasibility of constructing subsurface dykes to arrest underground run-off and augment recharge of ground water.

At Meenangadi grama panchayat in Wayanad, KAU has renovated vented cross bars (locally called cheerpu), helping farmers to raise paddy crop in about 40 acres. The structures are similar to check dams except in the pattern of excess flow.

“This year, crops in more than 30 lakh hectares have been severely affected by drought, resulting in a loss of nearly Rs.6,000 crore. The situation will worsen if proper plans for water conservation and management are not put in place,” P. Rajendran, Vice-Chancellor, KAU, told The Hindu.

“Kerala receives 2.78 times more rainfall than the national average and three times more than Tamil Nadu. But the advantage is offset by low water retention capacity due to the undulating topography, high intensity, low duration rainfall, extreme unevenness of rainfall in time and space, and very short length of rivers in Kerala.

Erratic monsoon and reclamation of wetlands have also made scientific methods of rainwater harvesting and conservation imperative to meet the domestic, agricultural, and industrial needs of the State,” Dr. Rajendran said. sStudies conducted by KAU show that harvested rainwater, purified through a filter, will remain potable for six months. The excess flow from storage tanks can be utilised for recharging open wells, tube wells, ponds, pits or abandoned wells. For irrigation, KAU recommends harvesting the rainwater and run-off and storing it in small farm ponds on individual plots or larger reservoirs for community use. Seepage loss can be prevented by lining the pond with sealants like black polyethylene or UV-resistant blue silpaulin sheet.

The university recommends the construction of percolation ponds or tanks as small water storage structures to harvest run-off from the catchments and to impound the water for better recharge of aquifers. Recharging through pits is advocated as a practice in areas where sub-strata restrict the downward passage of water and where aquifer is situated at a moderate depth.

In non-water logged areas, small rain pits can be made at various locations and around wells to enhance percolation of rainwater and increase the level of water table. Construction of check dams in shallow rivers and streams is proposed to replenish nearby groundwater reserves and wells.

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