Three-dimensional hyporheic exchange driven by local riverbed scouring below the in-stream structure.

This article focuses on the development and validation of a coupled surface–subsurface model that integrates the effects of local riverbed scouring (LBS) and in-stream structures on hyporheic exchange processes in rivers. Using field data from the Sheshui River basin in China, the model accurately simulates sediment transport, morphological evolution, and temperature variations, demonstrating that increases in weir height and inlet discharge enhance pressure gradients, temperature response areas, and hyporheic exchange fluxes. Importantly, incorporating the dynamic LBS effect significantly amplifies these parameters—raising the upstream-downstream pressure gradient by 1.89 times and hyporheic exchange flux by 1.28 times—highlighting the critical role of scouring pits in driving hyporheic exchange and informing river ecological restoration strategies. The study acknowledges limitations related to model generalizability, sediment heterogeneity, and biological-chemical interactions, suggesting directions for future research to improve model robustness and ecological applicability.