黄土坡面侵蚀方式演变过程中汇水坡长的侵蚀产沙作用分析

利用由位于坡面上部的供水装置和坡面下部的试验土槽组成的试验装置系统,通过模拟降雨试验,研究了不同降雨强度(50、75和100 mm/h)和不同坡度(15°、20°和25°)条件下坡面侵蚀方式演变过程中汇水坡长对侵蚀产沙的作用.结果表明,黄土坡面片蚀-细沟侵蚀-切沟侵蚀方式演变过程中汇水坡长对侵蚀产沙具有重要作用,且受降雨强度、坡度和侵蚀方式演变过程的综合影响.汇水坡长增加,使坡面片蚀-细沟侵蚀-切沟侵蚀发育速度明显加快,侵蚀产沙量明显增加.在坡面侵蚀不同发育阶段,汇水坡长对坡面侵蚀的产沙作用也不尽相同.当坡面以切沟侵蚀为主时,汇水坡长对坡面侵蚀产沙的作用最大,其次是以细沟侵蚀为主时.而以坡面片蚀为主时,汇水坡长对坡面侵蚀产沙的作用最小.通过对坡面侵蚀产沙量与汇水坡长的相关分析表明,它们呈正线性关系.

Contribution of upstream slope length to loessial hillslope erosion and sediment during erosion pattern evolution process

An experimental equipment,consisting of a water feed installation and a test box,is used to assess the contribution of upstream slope length to loessial hillslope erosion and sediment during erosion pattern evolution process at 50,75 and 100 mm/h of rainfall intensities and 15°,20° and 25° of slope gradients by using simulated rainfall.The results show that upstream slope length has great influences on the erosion and sediment yield during the erosion pattern evolution process from sheet erosion to rill erosion,and then to gully erosion.With the increasing of upstream slope length,the erosion pattern evolution process from sheet erosion to rill erosion,and rill erosion to gully erosion quickens and the sediment yields increase greatly.Meanwhile,at different stages of erosion pattern evolution process,the contribution of upstream slope length to loessial hillslope erosion and sediment is quite different.At the gully erosion stage,the effect of upstream slope length to hillslope erosion and sediment is the largest,the next is at the rill erosion stage,and the last one is at sheet erosion stage.The relationship between hillslope sediment yield and the upstream slope length is expressed as positive linear function.