Prediction of soil erosion under different land uses in the typical watershed of the Loess Plateau based on FLUS-CSLE model

Abstract: Soil erosion has posed a serious threat to the ecological balance and food security in the most fragile environment of the Loess Plateau. Frequent human activities are drastically changing the spatial pattern of land use in the economic and social development. Therefore, it is of great significance to predict the soil erosion under different strategies of land use for the regional coordinated development in the future. Taking the Jiuyuangou watershed as the research object, this study aims to propose an improved FLUS-CSLE model for the prediction of the spatial distribution pattern of land use in different scenarios. The vegetation coverage factor (B) and the tillage measure factor (T) were also calculated in the future scenario. The CSLE model was used to evaluate the soil erosion status in the historical period (2010-2020). The vegetation coverage factor and tillage measure factor were combined to predict the soil erosion under various scenarios of land use in 2025. Finally, a systematic analysis was made to determine the response of land use types to soil erosion status. The results show that: 1) The land use types were grassland (62.23%) and forest land (28.41%), followed by cropland, buildings, and water in the study area. There were the great variations in the spatial distribution pattern of land use. Specifically, the areas of forest and grassland increased by 8.36% from 2010 to 2020, whereas, the area of cropland was decreased by 30.3%. 2) The average modulus of soil erosion in the three years of 2010, 2015, and 2020 were 19.49, 15.83, and 20.7 t/(hm2·a), respectively, indicating a trend of first decreasing and then increasing. The soil erosion modulus of land use types was ranked in the descending order of the cropland (40.56 t/(hm2·a)) > grassland (18.79 t/(hm2·a)) > building (10.25 t/(hm2·a)) > forest land (8.02 t/(hm2·a)). 3) Under the positive ecological protection scenario, the area of forest and grassland in 2025 was basically the same as that in the natural development scenario, but the proportion of forest land increased. The area of forest and grassland was increased by 5.06% compared with the economic growth scenario. The area of cropland was increased by 1.20% compared with the natural development scenario and decreased by 14.73% compared with the economic growth scenario. 4) The soil erosion moduli were 24.3, 22.9, and 18.3 t/(hm2·a), respectively, under the natural development, economic growth, and ecological protection scenarios of the watershed in 2025. Therefore, an active ecological protection mode can be expected to appropriately expand the building area in the needs of economic development. Anyway, a rapid and efficient prediction of soil erosion can be given for the management strategies in the various scenarios of land use in the future. The findings can also provide the scientific reference for the decision-making on land use, as well as soil and water conservation in the watershed.