Spatial distribution of runoff and sediment on the different topography positions of vertical belts in loess region of hilly

There have been many arguments on and also have been many interests in the source of soil erosion at hilly region of the Loess Plateau and the slope-gully erosion sediment production. Erosion patterns correspond to the different topography position from hill slope to gully slope in soil erosion chain in the slope-gully system of loess region of hilly and gully. Spatial distribution of runoff and sediment in the vertical belts sections of soil erosion chain was studied by simulated rainfall examination on block diagram combined with multi-slope sections, also studied the accelerated erosion of the sediment from the upper slope. Results show that runoff increases from upper slope to lower slope. Runoff per unit area and time increased with the order of the upper hillside, the middle hill slope, the lower hill slope, and the gully slope. Also, all erosion patterns developed well on hill slope with rainfall intensity of 1.5 mm(min)-1and rill erosion extended from bottom of slope to the middle and the upper hill slope, gully slope display the gravity erosion such as slide and collapse. Rill erosion, in contrast, only occurred in the lower hill slope and gully slope with rainfall intensity of 1.0 mm/min, and gully erosion did not developed with rainfall intensity of 0.5 mm/min. Slope runoff and sediment production increase with an increase of slope gradient, slope length and rainfall intensity due to the effect of runoff from the upper slope, sediment yields of hill slope and gully slope increased greatly.