Assessing the efficacy of river bank filtration around a check dam in a non-perennial river for rural water supply in southern India.

Ideal locations for bank filtration wells were identified by assessing the efficiency of river bank filtration around a check dam in a non-perennial river located in southern India. The methodology of this study includes water sampling and water level measurements from existing wells, analysis of geochemical and biological parameters, pumping tests and borehole drilling. The conservative chloride and water level measurements indicate that production wells can be positioned up to 300 m from the check dam along the groundwater flow direction. It is recommended that if wells are not receiving 50% surface water contribution, then the production wells must be chosen within 110 m. In addition, the effectiveness of a river bank in improving water quality is evaluated by examining its hydraulic conductivity of 20 to 50 m/day (estimated using borehole data and pumping tests) and travel time and analysed water quality parameters. A significant reduction in microbiological load from surface water is evident even with a short travel time of 46 days. Substantial reduction in turbidity and improved geochemical characteristics were observed in wells located within the production zones which are supported by the Schoeller plot. The above results reveal that for the non-perennial river, in order to achieve maximum benefit through bank filtration, the same well cannot be used as a production well. Based on the water level in the check dam, the direction of groundwater flow and the percentage contribution of the river, it is necessary to shift the production well.