Identification of potential rainwater-harvesting sites for the sustainable management of a semi-arid watershed
In the present study, the potential locations for constructing different water-harvesting structures in a semi-arid watershed located at Goparajpalli, in southern India, were derived using GIS in three stages. The locations were first identified based on land use land cover, land slope, rainfall characteristics, soil texture and soil depth. Then a number of structures and suitable semi-arid rainfed regions have limitations in their runoff potential availability; these locations were further optimized based on the runoff available after in situ water conservation and storage in existing water-harvesting structures. The surplus runoff volume available in a normal year after storage was estimated to be 870 000 m3. Suitable locations for 25 rock fill dams (RFD), 74 farm ponds and 5 check dams were identified. These derived sites were validated by exporting to Google Earth and investigated for their suitability with ground truth information. At present, the number of structures existing is more than the optimum number of structures derived, but they have less storage capacity. Hence those structures such as farm ponds located at potential sites are recommended for desiltation and renovation by increasing their size along with lining so that they can be utilized for rainwater harvesting and supplementary irrigation. This methodology for identification of potential locations for water-harvesting structures is less time-consuming, more precise and can be utilized for the planning of large catchments to improve the water availability and productivity.