黄土裸坡土壤侵蚀过程研究

Soil Erosion Process Research of the Loess Bare Slope

黄土地区的土壤侵蚀严重地影响了当地和黄河下游地区的可持续发展,研究黄土地区的土壤侵蚀对于该地区的水土保持工作具有重要意义。采用人工模拟降雨试验的方法对黄土裸坡土壤侵蚀过程进行了研究,取得了如下结果:(1)不同雨强条件下,坡地土壤侵蚀随降雨过程的变化相似,可用幂函数相关方程进行描述,侵蚀强度变化的转变点在降雨开始后的10～15min之间;(2)不同雨强条件下,坡度对土壤侵蚀的影响相近且可用抛物线相关方程进行描述,侵蚀强度变化的临界坡度在25～30°间;(3)不同雨强条件下,坡地土壤侵蚀总量随坡长的变化可用幂函数相关方程进行描述,但坡长对侵蚀模数的影响比较复杂,表现为不同的形式;(4)不同坡度条件下,降雨强度对土壤侵蚀的影响相似且均可用线性相关方程进行描述,随着坡度的增大,土壤侵蚀随雨强增大而增加的越明显;(5)裸坡次降雨侵蚀经验模型为多元幂函数统计方程,裸坡条件下降雨强度对土壤侵蚀的影响最大,坡长与坡度的影响基本大体一致。研究结果表明,采取不同措施增加地面覆盖、停止陡坡耕种、截断坡地径流是治理黄土地区水土流失的有效途径。

Soil erosion of the loess areas greatly endangered sustainable development of the loess areas and the downstream areas of the Yellow River.Research on the soil erosion is significant to the soil and water conservation of the loess areas.With the simulated rainfall experiment,the bare-slope soil erosion of the loess areas was studied and the following results were made:(1) Under different rainfall intensity,hillslope soil erosion varied similarly with rainfall process and could be described with exponential equations.Erosion intensity didn't change until 10~15 min after rainfall began;(2) With rainfall intensity changed,slope gradient influenced soil erosion similarly and could be described with parabola equations.The critical slope degree was about 25~30° above which erosion intensity changed;(3) With rain intensity varied,general soil erosion amount changed with slope length and could be described with exponential equations.But slope length impacted erosion modulus more complicated with different forms;(4) With slope gradient differed,rainfall intensity affected soil erosion similarly and could be described with linear equations.The feature that soil erosion increased with rainfall intensity became more obvious to steeper slope;(5) The empirical model that simulated single-event bare-slope erosion processes was a plural exponential function.Rainfall intensity showed most influential to soil erosion,while slope length acted equally as slope gradient did on soil erosion.The result of study showed that taking different measures to increase ground cover,stopping cultivating on steeper slope and blocking hillslope runoff were effective ways of controlling soil and water loss in loess areas.