流域泥沙过程机理分析

Mechanism Analysis of Watershed Sediment Processes

黄土高原地质地貌复杂,是黄河流域的主要泥沙源区,并以黄土丘陵沟壑区和黄土高塬沟壑区为代表.沟壑区的不同部位具有不同的侵蚀产沙现象,并在不同的空间尺度上表现出迥异的水沙运动规律.为此需将流域分为坡面与沟道两大系统分别研究.本文描述坡面侵蚀产沙、沟坡区重力侵蚀和沟道水沙运动的主要现象,分析各水沙过程的主要机理.揭示出可依据坡面径流建立坡面侵蚀产沙模型;根据水流的诱发作用,用沟坡土体失稳的随机力学模型模拟沟坡重力侵蚀;考虑影响水沙运动的多种要素,建立沟道系统的高含沙水沙模型.流域泥沙过程机理的研究为建立符合实际物理图景的水沙模型系统,完成流域泥沙过程模拟提供基础.

The loess plateau who has complex geological and topographical condition is the main sediment source area, and represented by loess hilly-gully region and upland-gully region. Different positions in gully area have different phenomena of erosion and sediment yield, and even represent disparate patterns of water and sediment processes in different watershed scales. So for research, watershed should be divided into two kinds of elements as slopes and channels, which are connected by gullies. The processes of slope surface erosion and sediment yield, gravity erosion in gullies, water and sediment transport in channels are described in this paper, and the main mechanism of each process is also analyzed. Studying the mechanism of water and sediment processes is the basis of establishing the water and sediment model system which accords with the actual physical pattern and finishes the simulation of the whole water and sediment process. The feasibility of establishing the sediment yield simulation model of slope erosion based on slope surface flow, simulating gravity erosion in gullies based on random mechanics of soil body destabilization caused by flow current, and establishing hypereoncentration flow routing model in channel system considering different factors is revealed in this paper.