Study of groundwater recharge mechanism in Thal Doab

Groundwater recharge is a critical aspect in resource management. Isotope techniques can help determine the fresh recharge as well as its sources. In the present study (PCRWR Project), groundwater recharge mechanism was investigated in Thal Doab (area between the river Indus and the river Jhelum/Chenab). Surface water and groundwater (shallow and deep) samples collected from 216 stations were analyzed for stable isotopes. /sup 18/O concentrations of shallow and deep groundwater ranged from -12.2 to -2.2% and -11.8 to -4.8% respectively while gamma /sup 2/H values ranged from -87.4 to -17.6% and -84.2 to -34.3% respectively. /sup 18/O values of shallow and deep groundwater show similar geographical distribution pattern proving that they are interconnected and have similar recharge mechanism. Spatial distribution of /sup 18/O in shallow groundwater is depicted. Groundwater in the upper eastern part of the doab between Grot, Distt. Khushab and Mankera, Distt. Bhakar is mainly recharged by the rain (gamma /sup 18/O = -4.2%, gamma/sup 2/H = -24.6%). Sampling points surrounding the rain fed area show intermediate waters indicating the mixed recharge from rain and surface waters. As we move downwards from the rain-fed area, contribution of rain to groundwater recharge decreases while the rivers/canals contribution increases. At all remaining locations, groundwater is mainly recharged by the rivers either directly or through the canal system derived from them, which means that groundwater is a renewable resource and has good sustainable exploitation potential. (orig./A.B.)