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

摘要

To understand the causes of the past water cyclevariations and the influence of climate variability on the streamflow, lakestorage, and flood potential, we analyze the changes in streamflow and theunderlying drivers in four typical watersheds (Gaosha, Meigang, Saitang, andXiashan) within the Poyang Lake Basin, based on the meteorological observationsat 79 weather stations, and datasets of streamflow and river level at fourhydrological stations for the period of 1961-2000. The contribution ofdifferent climate factors to the change in streamflow in each watershed isestimated quantitatively using the water balance equations. Results showthat in each watershed, the annual streamflow exhibits an increasing trendfrom 1961–2000. The increases in streamflow by 4.80 m3 s?1 yr?1and 1.29 m3 s?1 yr?1 at Meigang and Gaosha,respectively, are statistically significant at the 5% level. The increasein precipitation is the biggest contributor to the streamflow increment inMeigang (3.79 m3 s?1 yr?1), Gaosha (1.12 m3 s?1 yr?1),and Xiashan (1.34 m3 s?1 yr?1), while thedecrease in evapotranspiration is the major factor controlling thestreamflow increment in Saitang (0.19 m3 s?1 yr?1). Inaddition, radiation and wind contribute more than actual vapor pressure andmean temperature to the changes in evapotranspiration and streamflow for thefour watersheds.For revealing the possible change of streamflow due to the future climatechange, we also investigate the projected precipitation andevapotranspiration from of the Coupled Model Intercomparison Project phase 3(CMIP3) under three greenhouse gases emission scenarios (SRESA1B, SRESA2 andSRESB1) for the period of 2061–2100. When the future changes in the soilwater storage changes are assumed ignorable, the streamflow shows an uptrendwith the projected increases in both precipitation and evapotranspiration(except for the SRESB1 scenario in Xiashan watershed) relative to theobserved mean during 1961–2000. Furthermore, the largest increase in thestreamflow is found at Meigang (+4.31%) and Xiashan (+3.84%) under theSRESA1B scenario, while the increases will occur at Saitang (+6.87%) andGaosha (+5.15%) under the SRESB1 scenario.