Spatial distribution of soil erosion in a black soil region of Northeast China studied using remote sensing and GIS techniques

The soil erosion intensity and its spatial distribution of Mashezihe watershed located at Bin county in the typical gentle hilly black soil region of Northeast China were studied using the Surface Erosion Grading Indicator (SEGI) method and Universal Soil Loss Equation (USLE) model. Land cover types and vegetation cover fraction derived from the Advanced Land Observing Satellite (ALOS) remotely sensed data were employed in conjunction with other spatial datasets (DEM and soil texture) for assessing soil erosion in the ArcGIS platform. Results show that with the support of remotely sensed parameters by ALOS, the USLE model is able to identify more detailed information on soil erosion than the SEGI method. The total areas of very slight and slight erosion identified by the two methods are very similar. However, the USLE model produced larger areas moderately, highly, and very highly eroded than the SEGI method. It also classified severely eroded areas of 52.25hm². According to grading regulation of soil loss tolerance issued by Ministry of Water Resources of China, the areas of very slight erosion (namely no obvious erosion phenomenon) and slight erosion identified by the USLE model are 21298.38 hm² and 22919.19 hm², accounting for 45.49% and 48.95% of the entire watershed, respectively, mainly in areas with slopes smaller than 5° and elevations lower than 200 m. Areas moderately, highly and very highly eroded are 1776.75, 486.56 and 286.88 hm², equivalent to 3.79%, 1.04% and 0.61% of the study area, mainly in areas with slopes ranging from 8° and 15° and elevations ranging from 200 to 300 m. The severely eroded areas are sporadically distributed in areas with slopes above 15° and elevations higher than 300 m.