The past and future changes of streamflow in Poyang Lake Basin, Southeastern China

Water resources have a close relationship with climate. The changes of streamflow affect the exploitation and utilization of water resources directly, and the social security and the stability of ecological system. Meteorological observations at 79 weather stations, and datasets of streamflow and river level at 4 hydrological stations were collected to analyze the changes of streamflow and underlying drivers in four typical watersheds within Poyang Lake Basin during the period from 1961 to 2000. The contributions of different factors to the changes of streamflow in four typical watersheds were quantitatively quantified using water balance equation. Then, the possible future change of streamflow was assessed using precipitation and evaporation projected by different GCMs under three different emission scenarios, including medium greenhouse gases emission scenario (SRESA1B), high greenhouse gases emission scenario (SRESA2), and low greenhouse gases emission scenario (SRESB1). The change of streamflow exhibited different characteristics the four watersheds exist different increasing trends during 1961 to 2000. The increase in streamflow in Meigang and Gaosha watersheds was at the 5% significance level, with increasing rate of 4.80 m3 s−1 yr−1 and 1.29 m3 s−1 yr−1, respectively. The increase in precipitation is the biggest contributor to streamflow increment in Meigang Gaosha, and Xiashan watersheds, while the decrease in evaporation is the major explainer for streamflow increment in Saitang watershed. Radiation and wind have larger contributions than actual vapor pressure and mean temperature to evaporation and streamflow. If soil water storage will not change in the future, with the increasing precipitation and the decreasing evaporation (not including the SRESB1 in Xiashan watershed), the streamflow shows an uptrend. Furthermore, the largest increase of Meigang watershed (+4.13%) and Xiashan watershed (+3.84%) appear under SRESA1B scenario while the increase of Saitang watershed (+6.87%) and Gaosha watershed (+5.15%) in SRESB1 scenario.