ABSTRACT
The hyporheic exchange driven by the weir structure and the corresponding temperature change in the hyporheic zone affect the river ecosystem, and play a crucial role in the river ecological restoration project. The size of the weir structure is a key influencing factor affecting the hyporheic exchange. In this paper, numerical simulations were carried out to investigate the changes in hyporheic exchange patterns driven by weir junctions, and the water-sand interface pressure and riverbed temperature were simulated at three different weir structure heights. The results show that the intensity of hyporheic exchange is positively correlated with the height of the weir structure. As the height of the weir structure increases, the hydraulic gradient at the water-sand interface also increases, creating downward and upward flows at the sediment-water interface upstream and downstream of the structure, respectively, and the area of the arc-shaped temperature region in the riverbed sediment close to the surface water becomes larger accordingly. This suggests that the weir structure will enhance the hyporheic exchange between surface water and groundwater, providing a habitat for benthic organisms, as well as a theoretical basis for practical river restoration projects.
