Abstract Sediment load is a critical issue in hydrologic process analysis and river basin management. Many studies have analyzed the impacts of rainfall or reservoir separately on the downstream sediment load; however, few researches investigated the coupled effect of rainfall and reservoir on sediment load change. In this study, a rainfall-augmented sediment trapping index (RSTI) that combines the impacts of effective rainfall and reservoir sediment trapping capacity was developed to attribute the sediment load change in the Wujiang River Basin (WRB) during the period of 1952–2017. Eight linear or nonlinear regression models were set up to investigate how to best utilize the proposed RSTI to reveal the coupled effect of rainfall and reservoir on the downstream sediment load of WRB. It is found that observed sediment load has a large decrease after 1984 when the Wujiangdu Reservoir was put into full operation while rainfall had only a slight change in the same period. The nonlinear regression model with RSTI as an explanatory variable (NSE = 0.837) has the best performance in simulating the observed sediment load series. These results might be helpful for the downstream sediment management under a changing environment.

中文翻译：

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有效降雨信息与水库泥沙截留能力耦合指数研究下游泥沙负荷变化

摘要 泥沙负荷是水文过程分析和流域管理中的关键问题。许多研究分别分析了降雨或水库对下游泥沙负荷的影响；然而，很少有研究调查降雨和水库对泥沙负荷变化的耦合影响。在这项研究中，结合有效降雨和水库泥沙截留能力的影响的降雨增强泥沙截留指数 (RSTI) 被开发来归因于 1952-2017 年期间乌江流域 (WRB) 的泥沙负荷变化。建立了八个线性或非线性回归模型，以研究如何最好地利用所提出的 RSTI 来揭示降雨和水库对 WRB 下游泥沙负荷的耦合影响。结果表明，1984年乌江渡水库全面投产后，实测含沙量大幅度下降，同期降雨量变化不大。以RSTI为解释变量（NSE=0.837）的非线性回归模型在模拟观测到的泥沙负荷序列方面表现最好。这些结果可能有助于在不断变化的环境下进行下游沉积物管理。