Characters of Sediment Load and Runoff Evolution and Influence of Reservoir: A Case Study on Sandy River in South China

In this study,based on the 52 years observed data of runoff and sediment load series at a important control station of a sandy river in the south China,the characteristics of the runoff and sediment load and the influence of cascade development have been analyzed by using Mann-Kendall method,coefficient of variation,analogy method and gray system theory.The results show that: 1) The characteristics of the sediment load and runoff evolution of the river have obvious decadal differences,the sediment load and runoff had upward trend before the cascade development,however,those have downward trend after the cascade develop ment,the sediment load has more significant changes than runoff;2) The sediment load and runoff evolution have positively related,the sediment load and runoff are less after the cascade development than before the cascade development of the former,the sedi ment load and runoff had significant changes in 1986 and 2008;3) The cascade development can lead to reducing sediment load and runoff,the cascade development is the main reason for the significant change of the relationship between the sediment load and runoff in 2008 and significantly decreasing of the sediment load and runoff in the mainstream of the river.