坡长对红壤侵蚀影响人工降雨模拟研究

Impact of Slope Length on Red Soil Erosion Under Simulated Rainfall

为解决南方红壤丘陵区裸坡面水土流失问题,该文采用人工模拟降雨(雨强30—150mm/h)结合试验土槽等方法(坡长分别为1、2、3、4、5m,坡度20°),研究了不同雨强下坡长对红壤侵蚀的影响,并初步探讨了侵蚀增强的临界雨强和设置水土保持措施的合理坡长,结果表明,产沙量随坡长的延长呈增大趋势,二者的关系可用幂函数(R2>0.80)表示,雨强越大,产沙量增速越快,增量越大.坡长延长相同长度时,产沙量不呈比例增加,初步建议在南方红壤丘陵区裸坡面可每隔4—6m设置水土保持措施,有效缓解坡面水土流失.坡面侵蚀产沙量随着雨强的增大而增加,坡长越长,产沙量随雨强增加速度越快,二者呈幂函数关系(R2=0.99),60mm/h左右是红壤丘陵区侵蚀增强的临界雨强;雨强、坡长与产沙量均呈正相关关系,雨强对裸坡面侵蚀产沙量的影响较坡长大.该研究为南方红壤丘陵区裸坡面水土流失治理提供一定的理论依据.

In order to solve soil loss issue on bare slope in red soil hilly region,this study investigated the impact of slope length on soil erosion under different rainfall intensities,the critical rainfall intensity and reasonable slope length for soil conservation by laboratory simulated rainfall（ with rainfall intensity 30—150mm / h） and soil flumes（ with slope length 1,2,3,4,5m,slope gradient20°）. Results indicated that sediment yield increased with increasing slope length under the same rainfall intensity,relationship between them could be described by power function（ Determination coefficient R2 0. 80）. The more and the quicker increase of sediment yield required the greater rainfall intensity. Increment of sediment mass was not proportional to the same slope length increase,consequently,this study suggested preliminarily that engineering measures of soil and water conservation on bare slope in red soil hilly region could be constructed at 3m intervals to truncate the slope length and decrease soil loss. Sediment yield increased with increasing rainfall intensity and it could be estimated with a power function of rainfall intensity（ Determination coefficientR2= 0. 99）. A quicker increase of sediment mass with increasing rainfall intensity required the longer slope length. Around 60 mm / h rainfall intensity was the critical value that resulted in sudden increase of erosion on bare slope in red soil hilly region,as a consequence,soil and water conservation measures should be strengthened when rainfall intensity is greater than 60 mm / h. There was positive correlation between sediment yield and rainfall intensity（ slope length）,moreover,rainfall intensity played more notable impact on sediment yield than slope length. This Study will serve to the control of soil and water loss on bare slope in red soil hilly region.