紫色土坡面植被覆盖度对水土流失影响研究

Research of Effect of Vegetation Coverage on Soil and Water Loss in Purple Soil Slope Land

植被是防止地面水土流失的积极因素,但在三峡库区紫色土关于植被对水土流失的影响还相对比较薄弱。本研究通过人工模拟降雨试验,分析不同草地覆盖度对紫色土坡地径流产沙的影响,定量研究不同草地覆盖度的减水减沙效益。结果表明:流量随草地植被覆盖度的增加而减小,小雨强时表现特别显著。特别是当植被覆盖度>60%后,径流量明显低于裸地及20%,40%植被覆盖度;植被覆盖度越高,植被降低径流含沙率的作用也就越明显,径流含沙量就越低;与草地的减沙功能相比,其削减径流作用明显弱于减沙效应,且盖度对坡面的减水特征值影响不太明显;植被覆盖的减流减沙效益在中小雨强时随雨强的增加而增加,在大雨强时,其减流减沙效益反而降低。

Vegetation is the positive factor preventing ground soil and water loss, but the research of effect of vegetation on soil and water loss is still very weak in purple soil in the Three Gorges Reservoir area. Artifi cial rainfall simulation experiment was used to analyze the effects of different grass coverage on runoff and sediment in purple soil slope land, quantitatively study the benefits of reducing runoff and sediment under different grass coverage. The results showed that the runoff flow decreased with increase of grass coverage, and it was particularly significant under small rainfall intensity. Especially when vegetation coverage was greater than 60~, the runoff volumes were significantly lower than those of bare land, the lands with 20~ and 40~ of vegetation coverage. The higher vegetation coverage is, the more obvious that reducing runoff and sediment yield, and the lower the sediment concentration is. Compared with grass-reduced sediment, it was obviously weaker for reducing runoff, and it was not clear that the effect of vegetation coverage on char- acteristic value of reducing runoff. The benefits of vegetation-reduced runoff and sediment increased with rise of rainfall under small and medium rainfall intensities, on the contrary, under the big rainfall intensity, the benefits of reduction of runoff and sediment declined.