Assessment of potential changes in soil erosion using remote sensing and GIS: a case study of Dacaozi Watershed, China

Soil erosion is a major global environmental problem. Therefore, a method of calculating potential soil erosion is necessary for soil and water resource management, as well as for assessing the risk of soil erosion. This study aimed to develop a simple method for calculating potential soil erosion change (PSEC) by combining the Universal Soil Loss Equation (USLE) and a Geographic Information System (GIS). The USLE model includes a rainfall erosivity factor (R), soil erodibility factor (K), cover management factor (C), slope gradient factor (S), length factor (L), and the supporting practice factor (P). Using a measured patch of soil and water conservation as the experimental unit, weather and soil data were combined to calculate R and K. Remote sensing images were used to extract vegetation cover (VC) and calculate C, while digital elevation models were used to extract and calculate S and L; land use maps were used to determine the P of each patch. The PSEC of each patch was then calculated according to the results of the above mentioned six factors. Finally, the PSEC of the entire study area was calculated on the basis of a patch area weighting method, which was validated in the Dacaozi Watershed in China, where a 1-year soil and water conservation project was implemented, beginning in November of 2013. In this study, the PSEC of the Dacaozi Watershed in May of 2017 was calculated, accounting for approximately 3 years of project implementation. The results showed that the average VC increased by 21.6% after 3 years of project implementation, whereas C decreased by 46.4%. The value of P did not change significantly from before to after project implementation. The average S decreased from 22.6 ± 12.1° to 21.3 ± 10.6°, and S decreased by 6.8%. In contrast, L increased by 33.3%. On the whole, the PSEC in the Dacaozi Watershed was 0.3925 and the potential soil erosion decreased by 60.75% after 3 years of conservation.