坡度和雨强对花岗岩崩岗崩积体细沟侵蚀的影响

Effects of Different Rainfall Intensities and Slope Gradients on Rill Erosion of Coluvial Deposits in Granite Benggang

崩积体是崩岗的重要组成部分,具有土质疏松、粗颗粒含量高、坡度大、易侵蚀的特征。该研究利用人工模拟降雨试验,对不同雨强(1.00,1.33,1.67,2.00,2.33mm/min)和坡度(20°,25°,30°,35°,40°)下的崩积体细沟发生、发育及形态特征进行分析。研究结果表明:发生细沟的时间随着坡度和雨强的增大而缩短;随着雨强的增大,沟头离坡顶的距离越短,沟宽和沟深增大,但细沟密度差异不明显;随着坡度的增大,垂向作用增加,但横向扩张能力相应地降低,造成坡面侵蚀深度增大,宽深比减小;随着雨强和坡度的增大,侵蚀方式从片蚀为主逐渐转变至细沟侵蚀为主;雨强对细沟侵蚀的影响大于坡度。

Benggang mainly consists of colluvial deposits with high erosivity leading to easy rainfall splash ero- sion or runoff scouring. This study aimed to analyze the rill erosion characteristics of the colluvial deposits under different simulated rainfall and slope conditions. Rainfall intensity ranged from 1.00 to 2.33 mm/min and slope gradient from 20° to 40°. The results indicated that： the time that the rill erosion happened was shorten as the slope and rainfall intensity increased; when the rainfall intensity increased, the distance of rill head from slope top became short, the width and depth increased, but rill density was not obviously differ- ent; when the slope increased, the vertical force increased, but the horizontal expansion capacity reduced ac- cordingly, so the depth increased, and the width-depth ratio decreased; and when the slope and rainfall in- tensity increased, the main erosion pattern changed from sheet erosion to rill erosion; the effects of rainfall intensity on rill erosion was greater than slope gradient.