黄土坡面细沟发育过程中的重力侵蚀实验研究

利用室内模拟实验的方法对典型坡度条件下黄土坡面细沟发育过程中的重力侵蚀规律进行了研究。通过对水沙测量结果的统计分析，同时结合实验中对重力侵蚀现象的观测，给出了实验条件下的临界重力侵蚀含沙量，以此为依据计算了重力侵蚀产沙量及重力侵蚀量达到总侵蚀量50%时对应的“中值时间”。结果表明，在细沟发育过程中，重力侵蚀产沙量存在着由增大到减小再到波动的变化趋势，这一趋势对坡面产沙变化具有重要的影响。重力侵蚀发生的中值时间则由小变大，反映了细沟发育的不同阶段重力侵蚀由以沟头坍塌为主向以沟壁崩塌为主的转化过程。

Experimental study on gravitational erosion process

Special experiments were conducted to analyze gravitational erosion variation in rill evolution process on loess slope. Based on the observation of gravitational erosion process in the experiment and the statistical analysis of the measured sediment concentrations at the egress of the slope, the critical values of sediment concentration caused by gravitational erosion under the experimental condition were specified. It was revealed that gravitational erosion load, which contributes to the main part of the slope erosion, varied with a tendency of increasing-decreasing-small-scaled fluctuation in the process. The concept of the gravitational erosion median time (GEMT) was given, which was defined as the time when the accumulated gravitational erosion load reaches half of the total in a rainfall. The test results show that GEMT decreased at the first and then fluctuated at the end of the rainfall due to the changing of dominant gravitational erosion type from sliding at the rill head to bank collapsing.