Spatial-Temporal Differentiation and Attribution of Soil Erosion in Northwestern Hubei Based on RUSLE and Geographic Detector

Northwest Hubei Province is a region prone to soil erosion. Investigating the spatiotemporal variations in soil erosion and identifying its underlying causes can offer valuable insights for guiding soil and water conservation efforts in the area. Based on the RUSLE model, we quantitatively analyzed the spatiotemporal variations in soil erosion in Northwest Hubei from 2005 to 2020. A geographical detector model was used to study the dominant factors of the spatial and temporal differentiation patterns of soil erosion, the degree of interactive coupling between multiple factors, and quantitative attribution of soil erosion-prone areas. The results indicate that, overall, the intensity of soil erosion in Northwest Hubei continued to decrease from 2005 to 2020. The average soil erosion modulus decreased by 16.3 t/(km2·a), and the soil erosion volume decreased by 200,000 t in 2020 compared to in 2005. Northwest Hubei showed a spatially divergent pattern of strong soil erosion intensity in the west and south and weak soil erosion in the central and north, with slight and mild erosion as a whole (accounting for 93% of the total erosion area). The land-use types in the study area were mainly forest land, and the proportions of forest land in 2005, 2010, 2015, and 2020 were over 60%. The soil erosion intensity of cultivated land was the highest among all land-use types. The area proportion of mild and above grade erosion intensity in this type was 85%, followed by forest land and grassland, with the percentage of the area of mild erosion intensity being 33.96% and 26.63%, respectively. From 2005 to 2020, each land-use type was transformed into another, and the transfer matrix results showed that cultivated land and grassland were mostly transformed into forest land, with a transfer area of 11.98%. Topographic factors markedly affected the soil erosion pattern: the soil erosion intensity in northwestern Hubei first increased and then decreased with the increase in elevation; the most significant erosion occured in the elevation zones of >200-500 m and >500-800 m, with proportions of the total erosion area being 47.7% and 31.8%, respectively. The soil erosion pattern was different under different slopes, and the area of >8°-25° was dominated by moderate, strong, and very strong erosion (the proportion of erosion is 55.4%); 65.6% of the area of >25° is strong and above high-intensity erosion. Given the impact of topographic factors on soil erosion, effective arrangements for soil erosion prevention and control measures should be made, keeping in mind the elevation distribution law and slope as the primary influencing factors. The results of geographical detection showed that slope and land use were the dominant factors affecting soil erosion, and the explanatory power of the two factors on soil erosion (q=0.479) was better than that of a single factor. Areas with slopes>35°, at elevations ranging between 500 and 800 m, showing an annual rainfall erosivity of 4,950.55-6,378.09 MJ·mm/(hm2·h·a), and cultivated land as the main land use type were identified as high-risk erosion areas. The results provide a scientific basis for soil erosion prevention, control, and land-use optimization in northwestern Hubei