Analysis of characteristics of soil erosion on slope land in the water source areas of Beijing and Tianjin

Slope land is a kind of important resource which can ensure food security and economic development.Data of Nanshan runoff plots in Chengde was used to study how slope length influenced soil erosion,sediment concentration and runoff depth in different length of plots.The results showed that both the slope length and rainfall intensity had influence on soil erosion.And the two factors changed with the slope length.When I10 was less than 0.25 mm/min,with the increase of slope length,soil erosion modulus decreased;when I10 was more than 0.25 mm/min,with the increase of slope length,soil erosion modulus increased at first and then decreased,and reached a maximum of 22 m.The change of mean runoff depth against slope length was identical to that of the volume of soil erosion;and the average runoff sediment was changed by rain intensity.So contour hedgerows or other measures can be used to reduce project investment and slope soil erosion and to improve land productivity.