Rainwater storage systems for rainfed ricelands of eastern India: results from research in Hazaribagh District
1994
Paul, D.K. | Tiwari, K.N. (Indian Council of Agricultural Research (India). Soil and Water Conservation Engineering, Central Rainfed Upland Rice Research Station)
India has 126.5 million ha of rainfed area, with the largest riceland (5 million ha) located in the State of Bihar. Rainfed ricelands have very low productivity mainly because of lack of irrigation and water management facilities, especially in the plateau region. To overcome this problem, the feasibility of small farm ponds (or) on-farm reservoirs [OFRs] for rainwater storage was studied at Hazaribagh during 1980-92. A study of seven villages in four adjacent blocks of Hazaribagh revealed that there are 2-3 private or community OFRs per village, with 0.5-07 ha reservoir area. These OFRs were constructed by the villagers with funds from the local government or from socio-religious organizations. Only farms with private OFRs have some dry-season crops. OFRs should be located such that 60 percent of the total area is used as catchment area. Preferably, OFRs should have 1:1 side slopes. Storage depth should be estimated on the basis of weekly reservoir water balance at 60 percent rainfall probability and 40 percent water loss due to evaporation, and seepage and percolation. For this situation, the projected life-sowing irrigation water requirement during critical drought spells should be thru irrigation using 10 cm water each, either during the initial, intermediate, or terminal phase of the rainfed rice, and two light irrigation for the second crop (lentil, chickpea, or linseed). The cost-benefit ratio of an unlined OFR comes to 1:4. Lining an OFR costs US$135/100 sq.m. A 37 percent net increase in groundwater recharging rate in a red loam soil area was achieved in the unlined OFR area
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