| Summary: | ABSTRACTThe double mass curve method has been widely used in studying the trend change of hydrological elements. Based on the deviation sequence of the linear regression of cumulative value and extreme value, this paper improves the trend analysis method of the double mass curve and puts forward the selection criterion of abrupt change point of runoff and sediment load. Using the improved double mass curve method, we find there are two abrupt change points of runoff and sediment load in the lower reaches of Jinsha River basin in 2000 and 2012, which correspond to the completion and use of Ertan Hydropower Station and Xiluodu Hydropower Station, respectively, and their contributions to the change of sediment discharge in the basin are −0.33 and −0.99, respectively. Compared with the double mass curve method before and after the improvement, the improved method has a higher accuracy in judging the trend of water and sediment, which provides a mathematical basis for the selection of abrupt change points.
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