中文摘要：

在已建立的黄土坡面细沟侵蚀CA模型基础上，侧重研究不同元胞大小对坡面细沟发育过程和细沟特征参数的影响。通过累积径流量和累积侵蚀量的Nash—Sutcliffe系数E-ns和误差系数R-e，分析元胞大小对CA模型有效性的影响。当保持模型其他参数和运行时间都不变时，元胞尺寸增大，细沟发育过程加速，细沟平均沟宽变宽，沟长变长，坡面径流和产沙的趋势提前，同时累积径流量减小，累积侵蚀量增加；当元胞尺寸变小时则相反。由于CA模型的流速是由元胞边长和时间步长的比值来决定的，所以只有其与实验坡面流速接近时才能提高模型的有效性。

英文摘要：

Based on the CA model of rill erosion, the research was focused on the effect of different si- zes of cells on the process and characteristic parameters of rill erosion on loess hillslopes as well as the availability of a CA model through the Nash-Sutcliffe coefficient E~ and error coefficient Re for cumu- lative runoff and erosion. The results show： when other parameters of model and the running time are unchanged, if the size of cell becomes bigger, the process of rill erosion will accelerate, the average width of the rill will get wider, the length will get longer, the trend of runoff and erosion will ad- vance, and at the same time, the cumulative runoff will decrease and the cumulative erosion will in- crease. If the size of cell becomes smaller, the effects will be reversed. In addition, the velocity of the CA model depends on the ratio of cell length and time step and the effectiveness of the model can be improved when it is closed to overland flow velocity.