Response of soil erosion to climate change and vegetation restoration in the Ganjiang River Basin, China

In the context of global warming it remains challenging to evaluate declining of soil erosion due to ecological engineering measures, and to isolate and quantify the contributions of various factors involved in soil erosion. For this study, soil erosion and soil conservation dynamics in the Ganjiang River Basin (GRB) in southeast China were quantitatively assessed based on the Integrated Ecosystem Services and Tradeoff Assessment (InVEST) model. Based on the analysis of the attribution factors of precipitation and Fractional Vegetation Cover (FVC), the dominant factors involved in soil erosion were determined by scenario comparison, where the areas with high sensitivity to erosion were quantitatively identified. The results revealed that both simulated value of soil erosion and sediment export initially decreased and then increased from 2000 to 2020; however, the total increases over the last 20 years were 14 % and 18.18 %, respectively. Moreover, the erosion intensity and sediment delivery ratio (SDR) decreased due to the influence of engineering measures such as reservoirs. Precipitation was the dominant factor that affected GRB soil erosion, with its contribution ratio (40 %-60 %) being as high as 94.74 %. In other words, in the GRB, precipitation inhibited the mitigation effect of high vegetation cover on soil erosion, and the contributions of FVC and precipitation showed a vertical trend. The extremely sensitive area caused by FVC is situated in the economically developed cities along the river system in the middle portion of the basin, while the extremely sensitive area caused by precipitation resides in the middle and upper reaches of the western portion of the basin. Based on this, prioritized protection areas can be determined.