Assessing agricultural managed aquifer recharge (Ag-MAR) for groundwater depletion mitigation in irrigated agricultural zones

Groundwater is essential for agricultural irrigation but faces severe depletion, leading to ecological degradation. In China’s Sanjiang Plain—an important grain-producing region—groundwater supplies over 90 % of total water use, creating serious sustainability challenges. Agricultural managed aquifer recharge (Ag-MAR) offers a potential solution, yet its success depends on site-specific geological and hydrological conditions, which are often overlooked by existing evaluation systems. This highlights a critical need to integrate surface water availability with subsurface hydrogeological features to better guide site selection. This study develops a region-specific framework combining geographic information systems (GIS), the analytic hierarchy process (AHP), and numerical groundwater modeling to assess Ag-MAR feasibility in the Sanjiang Plain. Six indicators, with geology as decisive factor, are used to construct a suitability evaluation system. Results show that 20.24 % of the region—mainly in the Jiansanjiang reclamation area—is highly suitable for recharge, using diverted river water for managed infiltration rather than relying on natural river–aquifer interactions. A groundwater model, calibrated for 2011–2020, is applied to predict recharge outcomes under three scenarios for 2020–2045: Scenario 1 (No recharge), Scenario 2 (Target-area recharge), and Scenario 3 (Optimized recharge distribution). Scenario 1 shows continued decline, while Scenario 2 reduces depletion by 94 %. Scenario 3 achieves a further 1.8 % reduction, aligning maximum water-level increases with optimal recharge zones. Under Scenario 3, depletion is virtually eliminated and water levels stabilize around 6 m. This framework provides technical support for sustainable groundwater management and offers transferable guidance for Ag-MAR implementation in similar agricultural regions.