黄土缓坡细沟侵蚀演化过程及其水流水力学特性实验研究

In this paper, rill dynamic development process and the temporal and spatial distribution hydraulic characteristics of flow were studied on Loess gentle slope of 15 degree through laboratory continuous rainfall simulation. The results showed that: (1) Dynamic development process of rill erosion could be presented as splash erosion-sheet erosion-drop pit-intermittent rill-continuous rill-rill collapse. Rill length developed rapidly and rill width and rill depth developed slower. To the end of the 5th rainfall, rill horizon density, the largest rill length, width and depth respectively increased 2.5, 10.2, 0.8, 1.6 times than initial erosion; (2) Velocity, runoff depth and Reynolds number increased with rainfall accumulation duration accompanied by minor fluctuations. The velocity in rill had a steady growth and runoff depth and Reynolds number in rill increased with fluctuant. Froude number had a larger fluctuation and it increased with the increasing of rainfall sessions. (3) Rain and grain resistance were decreased and form resistance increased with rainfall duration. Total resistance had a larger fluctuation in the first two rainfalls and it reached the minimum at the third rainfall. Total resistance increased in the last two rainfalls and reached steady. Grain resistance was the dominant resistance in first two rainfalls. However, form resistance increased to be the dominant resistance in last two rainfalls. The resistance in rill was least and upslope resistance was biggest.