不同植被格局下凸型坡径流流速时空变化及产沙研究

以凸型坡为研究对象,利用室内径流冲刷试验,研究了不同植被配置下凸型坡水蚀动力的变化过程以及侵蚀产沙的差异。结果表明:裸坡条件下径流流速呈现出极强的空间波动状态,随水力断面与坡顶距离的逐渐增加表现出先减小后增大的空间变化态势,导致侵蚀最为严重的部位出现在上坡上部和下坡上部。将草带布设于与坡顶距离60%～80%位置处对径流流速影响较大,降幅为22%,蓄水效益和减沙效益分别为12%和69%,能够较好地发挥直接拦沙的水土保持功效。不同植被空间配置下的径流量和产沙量均表现出与径流流速相一致的空间变化特征,随着草带距坡顶距离的逐渐增加,径流量和产沙量呈现出先增加后减小的趋势,植被通过调控水蚀动力过程实现了对径流和侵蚀产沙的调控。在此过程中,植被的空间配置方式改变了径流流速时空变化特征,从而对水蚀动力过程起到了很大程度的调控。研究结果有助于加深对植被、冲刷与水蚀动力过程之间耦合关系的理解。

Study on Temporal and Spatial Variation of Runoff Velocity and Sediment in the Convex Hillslope Under Different Vegetation Patterns

The convex hill slope was used as the object, using indoor runoff scouring experiments, the variation process of water erosion dynamics and variance of erosion sediment under different vegetation spatial configurations was studied. The results showed that the spatial variation of runoff velocity exhibited a fluctuating state, with first decreasing then increasing with distance between the hydraulic section and the slope top under bare-slope conditions. The most serious erosion was recorded on the upper part of the up slope and down slope. When the grass strip was planted at about 60%~80% of the up slope length, the impact on various runoff velocity was greater, and decreased by about 22%;by which water storage function is 12%, and sediment reduction function reach 69%. It could better exert soil and water conservation function by direct sediment interception and resulted in the lowest level of erosion in the experiment. The spatial variation trend of runoff and sediment was basically consistent with runoff velocity under different vegetation spatial configurations. With the increase of grass strip distance to the slope top, the runoff and sediment showed the first increasing then decreasing trend. The regulation effect of vegetation on erosion sediment transport was achieved through the regulation of the water erosion dynamic process. In the course of regulation, the vegetation spatial configuration altered spatiotemporal variation characteristics of runoff velocity, and thus played a significant effect on hydrological processes. The information of this study can be useful for better understanding the coupling relationship between vegetation, runoff scouring, and water erosion dynamics process.