不同植被覆盖度对紫色土坡面侵蚀过程的影响

为研究植被覆盖度对紫色土坡面侵蚀过程的影响,探讨有效控制水土流失的坡面植被临界盖度问题,利用人工模拟降雨试验与室内分析相结合的方法对紫色土坡面侵蚀过程进行分析。结果表明:(1)总体上,紫色土坡面产流量随植被覆盖度的增大而减小,二者之间呈线性负相关,但是植被覆盖度在25%以下,径流量变化不明显,植被覆盖度达75%时,径流量处于较低的稳定值,明显低于植被覆盖度0%,25%,50%;(2)坡面侵蚀泥沙量随植被覆盖度的增加而减少,二者呈二次项相关(R2=0.99),植被覆盖度25%以下对坡面减沙起到重要作用,50%的植被覆盖度是紫色土坡面有效控制水土流失的临界盖度;(3)侵蚀泥沙中以微团聚体(0.25mm)为主,各级团聚体基本上随着植被覆盖度的增加而呈现减少趋势;(4)通过统计分析,植被覆盖度对产流、产沙量的影响均为极显著(p0.01)。紫色土坡面植被覆盖度达到50%对涵养水源、保持水土起到至关重要的作用。

Effects of Slope Gradients on Erosion Under Different Vegetation Coverage on Purple Slopes

The paper analyzed the erosion processes of purple soil slopes using the method of artificially simulated rainfall experiment and lab analysis to study the effects of vegetation coverage on the erosion processes of purple soil slopes,and discussed the critical point problem of slope vegetation cover.The results showed that:(1) As a whole,with the increase of vegetation coverage,the runoff on purple soil slopes decreased.The was a significant negative relationship between the vegetation coverage and the runoff.However,when the vegetation coverage was less than 25 ％,the changes in runoff were not obvious.When the vegetation coverage reached 75 ％,the stable value of the runoff was low,being obviously lower than that when the vegetation coverage was 0％,25％,and 50％.(2) Sediment yield decreased rapidly with the increase of vegetation coverage.There was a significant quadratic term correlation between the vegetation coverage and the runoff.When the vegetation coverage was below the critical value of 25 ％,the vegetation played an important role in decreasing sediment load.A vegetation coverage 50％ was the critical coverage for soil erosion control on purple soil slope.(3) Soil microaggregates (＜ 0.25mm) were the main parts in eroded sediment.Basically,all levels of soil aggregates decreased with the increase of vegetation coverage.(4) Through statistical analysis,the vegetation coverage caused an extremely significant effect on runoff and sediment yield (p ＜ 0.01).Moreover,when the vegetation coverage reached 50％,vegetation played a vital role in soil and water conservation,and reduced soil and water erosion on purple soil slopes.