Abstract:In order to deeply analyze the characteristics and driving factors of runoff and sediment variation in watershed, and reveal the mechanism of runoff and sediment variation, the Lianshui watershed located in southern Jiangxi province was selected as the research area. Based on the hydro-meteorological and land use data from 1965 to 2020, at the annual scale and single rainstorm scale, we used the Mann-Kendall test method, cumulative anomaly method, runoff-sediment relationship curve and empirical statistical analysis method to analyze the characteristics of runoff and sediment variation, then established runoff-sediment relationship in different periods, and quantitatively evaluated the contribution rate of precipitation variation and human activities to the change of runoff and sediment. The results showed that at the annual scale, the runoff depth and sediment discharge showed a non-significant downward and extremely significant upward trend, respectively, and the abrupt change years were 1998 and 1995, respectively. Compared with the baseline period, the runoff depth and sediment discharge in different time scales of the changing period fluctuated more greatly, and the correlation between runoff and sediment was increased. The parameter a representing external human interference and the parameter b representing the sediment transport capacity of the river were increased. At the annual scale and single rainstorm scale, the contribution rate of precipitation variation and human activities to the decrease of runoff were -1.1%, 101.1% and 30.2%, 69.8%, respectively, while to the increase of sediment discharge were 0.5%, 99.5% and -2.0%, 102.0%, respectively. The research results could provide a basis for reasonable regulation of runoff and sediment, as well as the sustainable ecological development of watershed.