胶体颗粒在潜流带中沉积过程及机制

Deposition process and mechanism of colloidal particles in hyporheic zone

潜流带是河流地表水和地下水交混区域,是河流中重要的物质能量交换和水生生物栖息的场所,而胶体颗粒在潜流带中沉积,会改变潜流带中的水动力结构和生态环境。本文利用室内循环水槽实验和多物理场耦合的数值模拟方法,旨在研究胶体颗粒在河流上覆水与潜流带中的迁移过程和胶体颗粒在潜流带中沉积分布特征及其对不同因素的响应规律。结果表明:河流上覆水中胶体会逐渐被河床截留且截留胶体集中于河床浅层;沙波水平方向截留量呈现出迎水面较高、背水面较低的趋势;胶体在潜流带沉积的主要机制是潜流交换、颗粒沉降与河床截留作用。本文能为胶体颗粒在潜流带中的生态环境作用研究提供科学依据,并为河流生态环境修复、河流健康管理提供理论支持。

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.