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.