Groundwater Responses to Artificial Recharge of Rainwater in Badulla District in Sri Lanka

Two thirds of the country is considered a dry zone, where people face difficulties to access safe drinking water. According to the 2008 national census, pipe borne water coverage in Sri Lanka is around 34%, with the rest of the population depending on local sources such as wells, hand pump tube wells, small scale rural water supply schemes, rain water harvesting tanks and surface water bodies: irrigation tanks, canals, streams and springs. It is believed that contamination of water sources, by industry and through agricultural waste and fertilizers, is the main cause of the growing water-related health problems in the country. Most of the Schools in Badulla District are mainly depend on groundwater wells for its uses. Major problems in using the groundwater wells was the decreasing well water levels during dry season and quality deterioration. Therefore this study was designed to use the overflow of the rainwater harvesting tank for artificial recharging to increase the groundwater levels. In total seven were selected in seven schools and overflow of the rainwater harvesting tank was diverted to these wells. Water levels in the well and the rainwater harvesting tanks were monitored at weekly intervals. In addition pH, electrical conductivity and total soluble salts were measured in weekly interval. Results showed that the groundwater level increased due to artificial recharging of rainwater during the year 2018 even though the annual average rainfall of year 2018 (1827.9 mm) was less than that of year 2017 (1924.5 mm). Further the pH, electrical conductivity and total soluble salts in rainwater harvested water were within the safe limits of 6.5-8.5, 1500μS/cm and 500mg/L. However the EC and TDS values of rainwater harvested water is much less than the well water, therefore artificial recharging by rainwater do not post any threat to the groundwater.