From Hydroclimatic Extremes to Recharge Planning: A Multi-Evidence Decision-Support Framework for the Multan-Lodhran Aquifer, Punjab, Pakistan

Groundwater depletion in the Multan-Lodhran aquifer is intensifying as pumping expands faster than replenishment. This study explicitly separates two evidence types: (i) published baseline endpoints, which are recalculated here for transparent growth and water-budget indicators, and (ii) analyses performed in the present manuscript, comprising area-weighted GRACE/GRACE-FO storage residuals (2002–2024), a five-model bias-corrected NEX-GDDP-CMIP6 precipitation ensemble, precipitation-extreme diagnostics, and GIS-based managed aquifer recharge (MAR) screening. From the published baseline, built-up land increased from 346 to 417 km2 between 2000 and 2023; municipal wells rose from 16 to 92 by 2020; the urban-central groundwater decline was about 0.57 m yr−1; and the recalculated recharge-to-abstraction ratio declined from 1.15 in 2006 to 0.72 in 2020 and 0.58 in the 2045 projection. The new GRACE residual analysis indicates persistent regional storage loss, but the GRACE/GRACE-FO mission gap and residual surface-water contributions preclude treating the full-record slope as a homogeneous groundwater-depletion rate; pre-gap Theil–Sen slopes were −0.42 and −0.48 cm yr−1 for pre- and post-monsoon conditions. Under far-future SSP5-8.5, annual precipitation increases by 21.88%, while winter precipitation declines and monsoon/post-monsoon rainfall and upper-tail extremes intensify. These climate results describe precipitation opportunity rather than simulated groundwater recharge. GIS screening identifies low-slope alluvial areas with surface-water access as candidate investigation zones, not validated MAR sites. The framework is therefore intended for planning: site-specific hydrogeology, source-water quality, infiltration performance, and monitoring must be demonstrated, and recharge measures must be implemented alongside abstraction control.