关键词: 临界坡度, 侵蚀, 能量

Abstract: The effect of slope gradient on soil erosion has been studied extensively. A common result is that the amount of sheet erosion increases with the increasing of slope gradient. However, to a certain critical slope gradient. the amount of erosion decreases, because the increasing of the slope gradient decreases the actual project area of slope under a certain slope length and thus decreases the amount of flow on slope and the erosivrty of slope runoff. For a long time. scientists have attempted to determine the value of the gradient by both experiment and theory. Laboratory and site experiments give a common critical gradient of about 25?. but the theoretical results were different.In this paper. sheet erosion was supposed to be proportional to the flow energy exhausted to overcome the friction force of slope ground on the flow. The maximum energy exhausted produces the greatest amount of erosion. By solving the equation of energy it was found that the critical slope gradient is between 24癮nd 29?. depending on the ratio of flow depth to the diameter of soil grains which are equal or great than 84% in soil particle composition. The result is in consistent with the experimental result.

Key words: Critical slope gradient, soil erosion, energy