The Relationship Between Surface Roughness And Depression Storage

Surface roughness is resulted in the action of artificial management and soil erosion. It means concave and convex on the surface, and has great effect on overland runoff and erosion process. Depression storage capacity has close relationship with surface roughness. Compared with smooth surface, the depression storage capacity of rougher surface is greater. In order to understand the relationship between surface roughness and depression storage, we have to analyze the difference of depression storage under different surface conditions and their relationship. Artificial rainfall was applied and surface soil of farmland in Yangling was selected to study the effect factors of depression storage capacity, to analyze runoff-yielding time under different roughness conditions, to discuss changes of surface roughness and depression storage capacity at different erosion stage and their relationship. Based on experimental data estimation models were put forward to offer scientific basis for utilizing and exploring slope farmland.1 Surface roughness of three treatments decreased consecutively at three erosion stage. Artificial hoe decreased by 9.0%,6.5%,25.6% , artificial dig were 11.3%,6.4%,27.8%, contour tillage were 6.4%,3.9%,38.8%,dominent change occurred at grill erosion stage. During single rain event, surface roughness of straight slope increased by 32.5%,Surface roughness of artificial hoe slope, artificial dig slope and contour tillage decreased33.7%,33.0%,33.8% separately.2 Real depression storage capacity of artificial hoe decreased by 5.7%,15.0%,30.3% at three erosion stage, artificial dig were 7.0%,14.0%,40.8%; contour tillage were 8.0%,12.7%,46.5%. During single rain event, real depression storage of artificial hoe, artificial dig and contour tillage decreased by 39.8%,29.2%,42.5% separately.3 Maximum depression storage of artificial hoe decreased by 8.8%, 21.2% and 9.0% at three erosion stage. Artificial dig decreased by 7.2%,24.0%,8.1% at three erosion stage, and contour tillage slope decreased by 13.5%,11.0%,13.8%. During single rain event, maximum depression storage of artificial hoe, artificial dig and contour tillage decreased by 23.7%, 24.7%, 35.0% separately. The results showed that changes of surface roughness and depression storage were the same. Although change intensities were not the same at different erosion stage, it could also testify that surface roughness was the main effect factor of depression storage capacity. 4 The results of experiments showed that maximum depression storage capacity was significantly correlative with real depression storage capacity in linear relationship.At the same time, changes of them was the same at different erosion stages testified the close relationship between them from another point. Maximum depression storage could be replaced by real depression storage, and be used in runoff-erosion models.5 Depression storage was main effect factor of runoff-yielding time.Runoff-yielding time (T) was significantly correlative with depression storage capacity (DSC) in linear relationship: T(1.0)=2.4214DSC +2.5844 (DSC<10L) T(1.0)=0.7819DSC -1.7127 (DSC≥10L) T(2.0)=0.2737DSC +1.82.6 MUD index(MUD) was significantly correlative with depression storage (DSC) in linear relationship: DSC=3.9741MUD-10.404 (MUD>3.72) DSC=0.6456MUD+0.1166 (MUD<3.72).The relationship between depression storage(DSC) and R index(R), slope gradients(S) could be writhen as: DSC=6.427R-0.327S+2.404.