联合径流侵蚀功率与连通性指数识别流域侵蚀对植被恢复的响应

为识别植被恢复流域侵蚀变化过程，本研究构建了包含RUSLE(Revised Universal Soil Loss Equation)、IC(Index of Connectivity)和基于SWAT(Soil and Water Assessment Tool)的径流侵蚀功率方程所构成的侵蚀过程识别模型方法框架，以探究延河流域侵蚀过程的变化及对植被恢复的响应特征。结果表明：延河流域侵蚀情况总体持续向好，1985—2000年间多个年份的流域平均侵蚀模数超过80 t·hm^-2·a^-1，而在2015年左右下降至10～30 t·hm^-2·a^-1，植被恢复造成了流域侵蚀的动态变化，两者呈负相关的年际变化趋势，表明植被增加在较大程度上抑制了土壤侵蚀。径流侵蚀功率时空变异性较大，最大值从1985年的13.28×10^-4m⁴·s^-1·km^-2下降至2020年的4.40×10^-4m⁴·...

Response of soil erosion to watershed revegetation: role of sediment connectivity and erosion power

To identify the changing processes of erosion in revegetated watersheds, a model-based methodology was developed to simulate erosion processes and assess the spatial and temporal patterns of erosion and revegetation in the Yanhe watershed. The methodology combined the Revised Universal Soil Loss Equation(RULE), Index of Connectivity(IC), and Soil and Water Assessment Tool(SWAT)to model the variability in runoff erosion processes and the characteristics of the response to vegetation restoration. The results show that:damage due to erosion in the Yanhe watershed has generally improved:the average erosion rate had exceeded 80 t·hm^-2·a^-1 in most years between 1985 and 2000 and decreased to approximately 10-30 t · hm^-2 · a^-1 around 2015. The change in the soil erosion rate can be attributed to the degree of vegetation restoration, as evidenced by both measures showing a negative correlated interannual trend. The runoff erosion power decreased over time, from 13.28×10^-4 to 4.40×10^-4 m⁴·s^-1·km^-2 from 1985 to 2020, and a strong scale effect was observed:runoff erosion increased very quickly as a power function of the decreasing area, when the watershed area was less than 1 000 km². The IC results showed spatial variability, with small IC values in slope areas and large values in gullies. IC ranged from -13.11 to 1.95 across the watershed, being smaller in the middle reaches and larger in the upper and lower reaches, and decreased as the nested catchment area increases. IC was highly correlated with Normalized Difference Vegetation Index(NDVI)at the time scale(R²=0.98), and there was a gradual decrease in IC with increasing vegetation cover, suggesting that increasing vegetation impedes the degree of connectivity of sediment pathways. Meanwhile, IC and erosion were strongly correlated over time, indicating that areas with high IC have higher erosion risk and should be the focus of further erosion control. In general, the methodological framework demonstrated in this study has explanatory power and provides a new way to explore the erosion patterns in the watershed.