降雨移动方向对坡面侵蚀泥沙浓度的影响

为了探讨降雨移动方向对坡面下游出口处侵蚀泥沙浓度特性的影响，及其产沙产流量相对比值关系，本文主要通过室内小尺度坡面人工降雨物理模型试验展开研究.结果表明：降雨向上移动时，连续降雨过程各侵蚀泥沙浓度过程曲线形态相似，而降雨向下移动时,首场与后几场工况的泥沙浓度曲线差异鲜明；针对首场后的降雨工况，降雨向上移动泥沙浓度过程曲线均出现1个峰值，峰值泥沙浓度为6~90 g/L，而降雨向下移动时均出现2个峰值，相应值为11~68 g/L，且后者在弱雨强工况下标准差最小；2类移动工况的等效侵蚀泥沙浓度在不同雨强下随产沙峰值增加的增幅均表现为：弱雨强>中雨强>强雨强.总体上，相同条件（降雨强度、降雨历时、坡面土壤特性等）下，降雨向下移动时坡面侵蚀程度比降雨向上移动时大.

Impacts of moving rainfall on sediment concentration of soil erosion

Aiming to study the relationships between rainfall moving directions and soil erosion on hillslope, comparative plot-scale laboratory experiments were carried out in our study. The results showed that: shapes of the sediment concentration curves in one-day experiments were similar for the upstream-moving events, while significantly different for downstream-moving events. For events after the first in one-day experiments, there was only one peak sediment concentration when rainfall moves upstream, while two for the downtream conditions|furthermore, the range of peak sediment concentration was much larger for the upstream-moving events（6~90 g/L） than the downstream-moving events (11~68 g/L), of which standard deviation was the least in those downstream events with weak intensity (W). For both moving conditions, the equivalent sediment concentration with weak rainfall intensity showed the largest increase as the peak sediment yield increased, and strong intensity events (S) the least. It was concluded based on the characteristics analysis of sediment concentration that erosion of downstream-moving events was generally higher than the upstream-moving events under similar conditions.