Evaluation of Percolation Tank Efficiency on Groundwater Recharge: A Case Study for Karnampettai Percolation Pond, India

Abstract

Over abstraction of groundwater when compared to less amount of rainfall recharge throughout India is mainly due to increasing demands for irrigated agriculture causing severe groundwater depletion. Such an alarming situation is increasing unabated in spite of massive water harvesting measures that are implemented through watershed development programs (WDP). In order to improve the artificial percolation efficiency some new developmental programs are being implemented through managed aquifer recharge (MAR) (mainly percolation tanks and check dams). Keeping in view the well known Water Development Programs limitations due to the increasing number of recharging structures and huge cost involved in their construction, it has become necessary and important to evaluate and understand the MAR performance for sustainable management of groundwater resources. The present study examines the percolation efficiency of typical Karnampettai percolation tank located in Tamilnadu, South India using an integrated approach combining geophysical, hydrogeological and geotracer (radiotracer: tritium and chemical tracers: rhodamine B, bromide) investigations. The results indicated that percolation from the tank is 28 to 35 mm/day with an average percolation rate of 32 mm/day. The percolation rate is reduced progressively with a gradual decline of water level in the percolation tank. The average natural recharge (rainfed and irrigation fields) in the study area is 30 mm (8% of the rainfall). The study indicated that 65% of the total rainfall is lost due to soil moisture deficiency caused by evaporation and evapotranspiration. The study also reveals that the groundwater flow velocity near to the percolation pond is 2 m/day with effective groundwater recharge zone of 275 m.