2.1 Study area
The Yangtze River Basin (YRB) has a well-developed water system, with four main tributaries: the Yalong River, the Minjiang River, the Jialing River, and the Han River. This study was conducted in the middle and lower reaches of the YRB with the area of 1.8*106km2, located from 90°33’ to 122°25’ E longitude and 24°30’ to 35°45’N latitude (see Figure 2 ) (Li et al., 2021).
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Figure 2 Study area and location of 224 hydrometric stations

2.2 Data

The daily streamflow data of 267 hydrometric stations was downloaded from the Annual Hydrological Report of the People’s Republic of China, in which 224 hydrometric stations with 30 years records from 1970 to 1990 and from 2007 to 2016 were selected (see Figure 3 ). According to the China Meteorological Data Network (https://data.cma.cn/), daily precipitation, potential evaporation and temperature data from 1961 to 2016 were downloaded from 698 evenly distributed weather stations. The observed precipitation, potential evaporation and temperature data were interpolated into the whole Yangtze River basin with the method of Thiessen polygon (Meena et al., 2013). The interpolated precipitation, potential evaporation and temperature data of the basin area corresponding to 224 hydrometric stations were averaged. From the geospatial data cloud (http://www.gscloud.cn/), the 30-meter digital elevation model (DEM) was downloaded. Data on 361 reservoirs located in the mid-lower reaches of the YZR were retrieved from the Global Reservoir and Dam database (GRanD) (Lehner et al., 2011) .
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Figure 3 Streamflow record for 224 hydrologic stations. We here used complete decadal streamflow data for year 1970–1990 and 2007-2016.