Hydrological Modeling of Aquifer’s Recharge and Discharge Potential by Coupling WetSpass and MODFLOW for the Chaj Doab, Pakistan

Abstract

The estimation of the groundwater (GW) potential in irrigated areas is crucial for the sustainable management of water resources in order to ensure its sustainable use. This study was conducted in a selected area of the Chaj doab, Punjab, Pakistan, to quantify the impacts of the pumping and the recharge on the aquifer therein. To that end, a groundwater flow model (MODFLOW) and a groundwater recharge model (WetSpass) were coupled to assess the conditions of the aquifer. The model was calibrated manually on twelve-year data (2003–2014) against the observed groundwater levels, and it was validated with five-year data (2015–2019). Three main scenarios (divided into ten subscenarios) were simulated for the future prediction of the groundwater: Scenario-I (to assess the impact of the pumping if the prevailing conditions of the years from 2003 to 2019 were to continue until 2035); Scenario-II (to assess the impact of the pumping on the aquifer by increasing the pumping capacity by 25, 50, 75, and 100% for the coming 10 years); and Scenario-III (to assess the impact on the aquifer of the decrease in the average groundwater recharge from the river by 50% by following the same pumping trend). The Scenario-I results show that there would be an 18.1 m decrease in the groundwater table at the end of the year 2035. The Scenario-II results predict decreases in the water table by 2.0, 5.5, 9.8, and 14.3 m in the year 2029 as a result of increases in the pumping capacity of 25, 50, 75, and 100%, respectively. The results of Scenario-III show that, with the decrease in the recharge from the rainfall, there would be a 0.7 m decrease in the water table, and that, from open-water bodies, there would be a 2.4 m decrease in the water table. These results are very helpful for determining the recharge and discharge potential of the aquifer.