Effect Of Grassland Filter Belt On Runoff And Sediment Yield Of Two Kinds Of Brown Soil Slope

In order to control the soil and water loss in the earth rock mountainous area of North China,the optimal layout of grassland filter belt was put forward 9°.Under the conditions of slope gradient and 90 mm / h rainfall intensity,the influence of grassland filter arrangement on slope erosion was analyzed by indoor artificial rainfall experiment.The results show that:(1)The initial runoff generation time of strip layout under slope is 1.6 ～ 1.7 times of bare slope,and1.3 ～ 1.6 times of other three layout methods;The relationship of runoff yield of loess cinnamon soil under different layout modes is as follows: bare slope > Up slope slice >Up slope strip > Down slope slice>Down slope strip;the relationship of runoff yield of calcareous cinnamon soil under different layout modes is as follows: bare slope > Down slope slice> Up slope slice >Up slope strip >Down slope strip;In the aspect of flow reduction benefit,the strip layout under the slope has the best flow reduction benefit.The flow reduction benefit of the strip layout under the Loess cinnamon soil slope is 1.7 ～ 3.2 times of the other three layout methods,and the flow reduction benefit of the strip layout under the lime cinnamon soil slope is 1.3 ～ 4 times of the other three layout methods.(2)In terms of sediment yield,the sediment yield of the two kinds of soil under the four layouts showed bare slope > Up slope slice >Up slope strip > Down slope slice>Down slope strip;The results show that the sediment yield on the slope is 5.2 ～ 8.7 times of that on the slope,and the sediment reduction benefits of the four layout methods of loess cinnamon soil are 73.26%,97.79%,13.97% and 17.51%respectively;The sediment reduction benefits of calcareous cinnamon soil under four layout modes are91.59%,96.27%,10.57% and 18.14% respectively;The strip layout under the slope can effectively delay the occurrence time of rills,which has a significant effect in inhibiting rill development and reducing erosion and sediment yield;In the end stage of rainfall,the final content of sand and coarse silt of the two kinds of soil arranged on the slope is greater than that arranged on the slope.(3)In terms of runoff parameters,the increasing order of flow velocity of loess cinnamon soil under the four layout modes is Up slope slice >Up slope strip > Down slope slice>Down slope strip,and the final flow velocity is Up slope slice > Down slope slice>Up slope strip >Down slope strip,The results show that the increasing range of flow velocity in calcareous cinnamon soil is Down slope strip >Up slope strip > Up slope slice > Down slope slice,and the final flow velocity is Up slope strip >Down slope strip > Down slope slice >Up slope strip.For loess cinnamon soil,strip arrangement can slow down runoff velocity;The resistance coefficient under strip layout is greater than that under sheet layout.The resistance coefficient of loess cinnamon soil under four layout modes is Up slope strip >Down slope strip >Down slope strip > Up slope slice.The resistance coefficient of calcareous cinnamon soil under four layout modes is Up slope strip >Down slope strip >Up slope strip > sheet off slope.