Spatiotemporal Variation Characteristics and Attribution Analysis of Sediment Transport in the Ganjiang River Basin

［Objective］ The aim of this study was to investigate the spatial and temporal variation of sediment transport in the Ganjiang River Basin, and to explore the contribution of climate change and human activities to sediment changes of the basin quantitatively, in order to provide a reference for soil erosion control, water and sediment resource management. ［Methods］ Data of sediment transport monitoring and precipitation history from 1960 to 2020 at 15 main hydrological observation stations located in upper, middle and lower reaches of the Ganjiang River Basin were collected. The spatial and temporal changes of sediment transport were analyzed by the linear trend method, Mann-Kendall trend test and Pettitt mutation test were used in combination with double mass curve to quantitatively analyze the contribution of the influencing factors. ［Results］ 1) Annual sediment transport in the upper, middle and lower reaches of the Ganjiang River Basin showed a significant decreasing trend from 1960 to 2020 (|Z|>2.58). The reduction rate of Waizhou, Xiajiang and four stations of the upper reaches were 2.143×105, 1.661×105 and 0.812×105 t/a, respectively, and there were mutations in sediment transport in 1994, 1992 and 1998. 2) The multi-year average sediment transport modulus of the sub-basins were high in the south and low in the north, and the temporal variation showed a trend of increasing first and then decreasing in the upper reaches, and decreasing in the middle and lower reaches. Compared with 1960—1987, the average sediment transport modulus in the upper, middle and lower reaches decreased by 51.32%, 104.95% and 105.03%, respectively from 2001 to 2020.3) The temporal and spatial variation of sediment load in the basin was affected by the topography, soil and water conservation measures, etc. Human activities were the leading factor for the reduction of sediment transport in the Ganjiang River Basin. ［Conclusion］ The sediment production from erosion in the Ganjiang River Basin has significantly reduced, but the upper reaches are still the key areas for soil erosion control in the future.