PROTECTING A HERITAGE-SITE GROUNDWATER-DEPENDENT POND USING TRANSIENT MODFLOW SCENARIOS AND MANAGED AQUIFER RECHARGE

A groundwater-dependent sacred pond at the Katas Raj heritage site (Salt Range, Pakistan) has experienced declining water levels associated with sustained groundwater abstraction for agriculture, domestic supply, and industrial expansion. To quantify the drivers of decline and evaluate management options, we developed a transient, two-layer MODFLOW model using hydro stratigraphic information, pumping records, and time-varying recharge for 2011-2020, and assessed model performance against available observation-well heads. Water-budget results indicate that current withdrawals exceed natural recharge by approximately 40%, leading to persistent groundwater depletion and an average drawdown of about 0.5 m/year in the vicinity of the pond, with larger localized declines under future stress scenarios. Scenario testing shows that stabilizing groundwater levels near the pond requires an approximately 40% reduction in abstraction relative to current conditions. Managed Aquifer Recharge (MAR) implemented through infiltration ponds provides a complementary intervention, supplying an estimated 13,333 m³/day of infiltration and reducing the modelled water-budget deficit by roughly 60%. These findings translate model outputs into actionable thresholds for pumping control and MAR sizing to protect groundwater-dependent heritage water bodies under increasing demand and recharge stress, and provide a scenario-based workflow applicable to similar settings facing competing groundwater uses.