Distribution Characteristics and Coupling Relationship Between Soil Erosion and Hydrologic and Sediment Connectivity in Changchong River Basin

[Objective] To clarify the distribution characteristics and coupling relationship between soil erosion and hydrologic and sediment connectivity in Changchong River Basin, and to provide basis for soil erosion control and soil erosion prevention in this area. [Methods] By using the RUSLE model and introducing the connectivity index (IC) and topographic humidity index (TWI), the distribution characteristics of soil erosion, hydrological and sediment connectivity in the Changchong River Basin in 2021 were quantitatively evaluated by GIS platform. The effects of different slope, land use, elevation and slope direction on soil erosion intensity and hydrologic and sediment connectivity in small catchments were discussed, and the coupling relationship between soil erosion and hydrologic and sediment connectivity was analyzed through spatial autocorrelation. [Results] (1) The average soil erosion modulus in the Changchong River Basin was 380 t/(hm2·a), and the soil erosion intensity was mainly slight erosion, which gradually intensified from north to south. (2) The high hydrological and sediment connectivity is mainly distributed in cultivated land, and the opposite is true in forest and grassland land. The higher value is mainly located in the low-lying flat area with low slope and easy water accumulation, while the lower value is mainly in the steep mountainous area. (3) Topographic factors and land use types significantly affected soil erosion and hydrological and sediment connectivity (p<0.01). The relatively low soil erosion intensity and hydrological and sediment connectivity levels, the higher erosion intensity and connectivity levels accounted for a higher proportion of arable land, but a smaller proportion of woodland and grassland. Among the hydrological and sediment connectivity grades, the proportion of 5° ~ 10° and 10° ~ 15° slope, 90.30 ~ 131.96 and 131.96 ~ 175.34 m elevation area is higher. The higher the grade, the higher the proportion of sunny slope area is. (4) Soil erosion has a significant positive correlation with hydrologic and sediment connectivity, mainly reflected in slope, slope direction, land use and elevation. [Conclusion] Improving the vegetation coverage and dominance of the Changchong River Basin to reduce its hydrologic and sediment connectivity can effectively reduce soil erosion and sediment production, and has an important impact on the ecological environment management, water and sediment control, and scientific prevention and control of soil and water loss in the small watershed.