Estimation of Groundwater Recharge Using Isotope Mass Balance Approach in the Tawi Watershed, Jammu District, Jammu and Kashmir, India

ABSTRACT The present study aims to identify potential areas of groundwater and surface water interaction and to quantify them across the three physiographic zones (Northern Hilly area, Kandi, and Sirowal) of the Tawi watershed. The stable isotopes of Oxygen and Hydrogen were used to evaluate the interaction between river water and groundwater, along with quantification of the groundwater recharge. The results demonstrate that precipitation is the prime groundwater recharge source in these physiographic zones of the Tawi watershed in Jammu District. The river water samples exhibit enriched δ18O isotopic values compared to groundwater samples across the physiographic zones. Also, the inverse altitude gradient of δ18O isotopic values of groundwater in the Sirowal belt shows more negative isotopic signatures than those of the Kandi belt and Northern Hilly area. The Ranbir canal shows significantly depleted δ18O isotopic values in the Sirowal belt, with up to 83% of the canal contribution to the groundwater recharge. The Tawi River explicitly shows a remarkable contribution to groundwater recharge near the banks during monsoon, whereas the value reaches up to 80% in the Kandi belt.