Identification of critical source areas of soil erosion on moderate fine spatial scale in Loess Plateau in China

Abstract

Critical Source Areas (CSAs) are considered as priority areas for soil conservation and it is essential to identify CSAs for effective watershed management. Soil and water assessment tool (SWAT) model is a useful tool in identifying CSAs. Previous studies that used SWAT for CSAs identification were almost carried out on the basis of sub-watershed level which was too coarse to capture spatial detail of soil erosion. This research identified CSAs of soil erosion at a moderate fine spatial detail scale in a small watershed of Loess Plateau in China using SWAT model. CSAs were identified based on the 4-year average annual sediment yield of hydrological response units (HRU). The result shows that CSAs were mainly located in steep slope farmland areas and gully dominated areas. CSAs covered 10% areas of watershed, and contributed 30% sediment yield to the watershed. Such a trend is more obvious under larger storms. This could imply that CSAs identification on HRUs level is suitable for site-specific management design. This study also confirms that CSAs identification could be a potential approach assisting water quality control.