草本植被覆盖对坡面降雨径流侵蚀影响的试验研究

EFFECT OF GRASS COVERAGE ON SEDIMENT YIELD OF RAIN ON SLOPE

通过野外人工模拟降雨试验,研究了草本植被覆盖对坡面降雨径流侵蚀的影响,并从径流侵蚀功率和降雨侵蚀力两个方面对比分析了草本植被对坡面侵蚀动力的调控效果,结果表明草本植被覆盖深刻影响降雨侵蚀动力,并最终对坡面径流侵蚀量产生较大的影响。植被覆盖度为0%～60%时,产流产沙量随植被覆盖度的增加迅速降低,植被覆盖度>80%时,覆盖度的增加不能引起产流、产沙量的大幅度下降,植被水沙调控作用趋于稳定,确定本研究的临界植被覆盖度为60%～80%;以径流深和洪峰流量模数表示的坡面径流侵蚀功率以及降雨侵蚀力等侵蚀动力指标均与侵蚀产沙量呈正相关关系,但径流侵蚀功率与产沙量具有更强的相关性,说明径流侵蚀功率能更好地模拟侵蚀动力;以径流侵蚀功率/侵蚀量表示植被覆盖度对侵蚀结果的影响,反映了临界植被覆盖度的存在,可以作为评价植被侵蚀动力调控效应的一个指标。

Based on a simulated rainfall experiment in the field, effect of grass coverage on slope erosion was studied, and comparison between runoff erosion power, expressed by runoff depth and peak discharge modulus, and rainfall erosion force by sediment yield was conducted to analyze the role of the vegetation regulating erosion dynamics on the slope. Results show that the vegetation cover affected runoff and sediment generation significantly. Runoff and sediment yield reduced rapidly with the vegetation coverage increasing from 0% to 60% , however, when coverage exceeded a critical value, 80% , the effect was not so significant and leveled off. The critical vegetation coverage ranging from 60% to 80% is determined in this study. Both runoff erosion power and rainfall erosion force were positively related with sediment yield, and the former was more significant than the latter, suggesting that runoff erosion power may be used to better simulate erosion dynamics. The presentation of the effect of vegetation coverage on erosion by the ratio of runoff erosion power/ erosion volume reflects existence of critical vegetation coverage, which can be used as a new index to evaluate regulatory effects of vegetation cover on soil erosion dynamics.