关键词: 侵蚀, 泥沙, 细沟侵蚀

Abstract: In the process-based models, rill erosion prediction is an important component, and the prediction sensitivity of soil loss from a given hillslope depends greatly on the calculation of rill erosion. Rill erosion occurs on slopeland only when an increase in flow shear from the increased rill spacing causes flow shear to exceed the critical threshold of soil erosion. So, in the process based models of rill erosion, critical hydraulic conditions of rill initiation have to be determined before the model can be used to predict soil loss for a given type of soil. This paper reports the results of a series of laboratory experiments, aiming at a better understanding of overland flow and sediment production mechanisms on hillslopes. The results are presented about threshold hydraulic condition needed for rill formation, characteristics of sediment delivery and velocity of flows in rill, as well as a relation of gradient to rill erosion. The process of rill erosion on the tested slope was examined and described. On the basis of statistical analysis, the formula to calculate critical flow volume of rill formation under the this test conditions was suggested as follows:Q_c=1.36S₀^-1.37 where, Q_c is the critical flow volume for rill initiation,S₀is slope gradient, and flow detachment rate in rill was empirically approximated by:E=0.035Q^1.065S₀^1.811 where, E is detachment rate of rill flow, Q is flow volume in rill, and S₀ is slope gradient.

Key words: erosion, sediment, rill erosion