Fig. 4

a Time series of δ¹⁸O in the Changjiang river water in Nantong and precipitation over the Changjiang catchment. The 2σ errors for precipitation are calculated with Eq. (1) based on the deviation for monthly precipitation for each sub-basin (see Table 1). See the text for a detailed calculation of precipitation isotopic composition. Time series of δ¹⁸O in Changjiang River in Chongqing and Datong, Dongting Lake and Poyang Lake are likewise compared. The sampling time for each time series is shown in bracket (YY/MM ~ YY/MM). b Daily river discharge data of the Changjiang River at different gauge stations from October 2012 to December 2014. All discharge data refer to http://yu-zhu.vicp.net/. The temporal variations of δ¹⁸O in the Changjiang river water in Nantong are displayed for the comparison. c Correlation between δ¹⁸O time series (17 days shift forward) in the Changjiang river water in Nantong and the defined lake contribution in terms of water discharge ratio. The water level at the Three Gorges Reservoir is retrieved from the Wanxian Station (http://yu-zhu.vicp.net/)