Deposition process and mechanism of colloidal particles in hyporheic zone

The hyporheic zone is a region where surface and subsurface water mix in rivers. It is an important area for the exchange of mass and energy and an essential habitat for aquatic organisms. However, the deposition of colloidal particles in the hyporheic zone can modify the hydrodynamics and ecological environment of the river system. Through recirculating flume experiments and numerical simulations, this paper aims to investigate the transport of colloidal particles between stream and streambed, and clarify the pattern of colloidal particles' deposition in the hyporheic zone as well as the influence of different factors over particles' deposition. The results show that the colloidal particles in the overlying water will gradually retain in the streambed and accumulate in the shallow layer. The horizontal distribution of the retained particles tends to be higher on the stoss-side and lower on the lee-side. Hyporheic exchange, settlement of particles and retention of streambed are 3 most important factors in the deposition of colloids in the hyporheic zone. This paper can be helpful for understanding ecological and environmental functions of colloidal particles in hyporheic zone, and it can provide theoretical support for environmental and ecological restoration and health management of rivers.