模拟降雨条件下坡度和降雨强度对桂南崩积体侵蚀产沙的影响

Effects of Slope Gradient and Rainfall Intensity on Sediment Yield in the Colluvial Deposits of Southern Guangxi Under Simulated Rainfall

[目的]探究坡度和降雨强度对崩岗崩积体坡面侵蚀产沙特征的影响,为桂南地区崩积体水土流失预测及其防治提供科学依据。[方法]采用室内模拟降雨试验,研究不同坡度(15°,20°,25°)和降雨强度(60,90,120 mm/h)条件下崩积体坡面侵蚀产沙过程。[结果]各坡度条件下,60 mm/h降雨强度时,崩积体坡面侵蚀速率变化过程较为稳定,且侵蚀速率多低于5.0 g/(m^(2)·s),并呈现出一定的下降趋势;90~120 mm/h降雨强度下,侵蚀速率呈先波动增大后波动减小的变化趋势。降雨过程中侵蚀速率最大值随降雨强度和坡度的增大而增大,侵蚀速率最大值出现的时间集中在0~25 min内,且随坡度的增大有提前的趋势。次降雨产沙量(3.64~48.07 kg/m^(2))随降雨强度和坡度的增大而增大,与降雨强度和坡度之间的非线性回归结果(幂函数)优于线性回归结果。次降雨产沙量与坡度和降雨强度的交互项相关性最为显著,二者呈极显著线性函数关系。[结论]次降雨产沙量对降雨强度的敏感系数要高于对坡度的敏感系数,降雨强度对次降雨产沙量的影响强于坡度,崩积体侵蚀防治中建议做好坡面排水措施。

[Objective]To reveal the influences of slope gradient and rainfall intensity on the erosion and sediment yield characteristics of the colluvial deposits from Benggang,and to provide a scientific basis for soil and water loss prediction and control of the colluvial deposits in southern Guangxi.[Methods]The indoor experiment of simulated rainfall was carried out to investigate the erosion and sediment yield phocesses of colluvium slope under different slope gradients(15°,20°,25°)and rainfall intensities(60,90,120 mm/h).[Results]The results showed that the variation processes of the erosion rate of the colluvium were relatively stable,and the erosion rate was mostly lower than 5.0 g/(m^(2)·s),and showed a certain downward trend when the rainfall intensity was 60 mm/h under different slope conditions.While,the erosion rate fluctuated to increase first,and then decreased under the rainfall intensity of 90 to 120 mm/h.The maximum erosion rate during each rainfall increased with the increase of rainfall intensity and slope gradient,and the maximum erosion rate occurred within 0 to 25 min and tended to advance with the increase of slope gradient.The sediment yield amount(from 3.64 to 48.07 kg/m^(2))increased with the increase of rainfall intensity and slope gradient,and the nonlinear regression result(a power function)between the sediment yield amount and rainfall intensity and slope gradient was better than the linear regression result.The correlation between sediment yield amount and the interaction of slope gradient and rainfall intensity was the most significant and showed a high-significant linear function relationship.[Conclusion]The sensitivity coefficient of the sediment yield amount to rainfall intensity was higher than that to slope gradient,and the influence of rainfall intensity on sediment yield was stronger than slope gradient.gradient Slope drainage measures should be taken in the prevention and control of colluvial deposit erosion.