Dynamic Simulation of Water Levels in Large-Scale Infiltration Galleries Using a Surface Water-Groundwater Coupled Model
The extraction process of large-scale infiltration galleries significantly alters surface water-groundwater exchange dynamics. Existing models often simplify the gallery as a boundary condition or adopt loosely coupled schemes, constrained by iterative exchange algorithms, failing to capture dynamic water flux interactions and transient responses. This study focuses on the large riverbed infiltration and purification water supply project in Shijiazhuang, China, establishing an integrated three-domain fully coupled numerical model—encompassing surface water, groundwater, and the infiltration gallery—using the dual-node coupling approach in HydroGeoSphere. The model sets two upstream inflow scenarios (wet and dry seasons) and simulates groundwater level evolution and water exchange processes under two operational modes: single-pump extraction at 1000 m³/h and no pumping. Results show that groundwater levels decline markedly under pumping, with the most pronounced response in the dry season, where maximum drawdown reaches approximately 1.24 m. Monitoring wells near the gallery show an earlier hydraulic response to pumping, reaching peak drawdown rates about 2–3 days sooner than wells farther away. At steady-state balance, surface water contributes more recharge to groundwater during the wet season than in the dry season, and water exchange between the gallery and aquifer is substantially enhanced under pumping. Spatially, water exchange concentrates primarily around transverse and longitudinal gallery sections, consistent with localized permeability enhancement from the perforated structure. These findings reveal groundwater dynamics and multi-domain interaction mechanisms under operational conditions, providing a theoretical basis for planning, design, and management of similar riverbed infiltration projects.