Groundwater Recharge in Crisis: Analyzing the Impact of Urban Growth on Monterrey’s Aquifer Health in the Face of the Rio Grande’s Current Conditions

The Monterrey Metropolitan Area (MMA), the largest urban and industrial center in northeastern Mexico, faces increasing groundwater stress driven by rapid urban expansion, recurrent drought, and limited surface-water availability. Since 2024, the San Juan River has been considered a potential source of treaty water under the 1944 U.S.–Mexico Water Treaty, further intensifying pressure on regional water resources. This study evaluates changes in groundwater recharge potential between 1990 and 2022 using an integrated Remote Sensing–Geographic Information System framework combined with the Analytic Hierarchy Process. Eight thematic layers—geology, structural lineaments, slope, geomorphology, precipitation, drainage density, Normalized Difference Vegetation Index, and soil type—were weighted to derive a Groundwater Potential Index and delineate recharge zones. Results show a pronounced redistribution of recharge capacity over 32 years. Very low recharge areas increased by 1021.3 km2, while very high recharge zones decreased by 100.4 km2. In total, more than 1100 km2 experienced degradation in recharge potential, mainly associated with urban growth and land-use change. These findings highlight the urgent need for sustainable groundwater management, stronger land-use planning, and protection of recharge areas. Coordinated action among stakeholders and robust regulatory enforcement will be essential as the region navigates future growth and international water obligations.