April to June average streamflow reconstruction for Weihe River upper reaches during the past 377 years by means of tree rings
Purposes—To investigate the historical changes in runoff flow in the upper reaches of the Weihe River basin over the past 377 years,and provide key information needed for water resource assessment,such as the variability,intensity and periodicity of hydrological elements on a centennial scale,as well as their long-term evolutionary characteristics.Methods—Correlation analyses,linear regression equation and power spectrum method were utilized to determine the response relationships between tree rings and streamflow,model construction and period signals.Results—The variations of April to June average streamflow during 1630-2006 were reconstructed.The variance interpretation of 34.9％ existed in the calibration period from 1945 to 1979.The reconstructed tree ring streamflow sequence identified 51 extreme high-flow years and 54 low-flow years,accounting for 13.53％and 14.32％over the total 377 years.Extreme high-flow epochs with more than three consecutive years appeared in 1647-1649,1699-1701,1843-1845,1905-1907 and 1909-1911,while extreme low-flow years occurred in 1722-1727,1747-1749 and 1763-1765.The values of high and low stream-flow spans based on the 11-year moving average were quantified,and the significant low-flow years had a good relationship with the regional large-scale drought events.The reconstruction had a periodic signal of 50.400 a and 2.290 a.Conclusions—The variations of tree ring seasonal streamflow of the Tianshui section for the middle-upper reaches of the Weihe River during the past 377 years were char-acterized by high variability and large amplitude,and the hydrological climate changes in the basin were closely related to large-scale climate drives such as the Pacific Decadal Oscillation and El Nino-Southern Oscillation.
万方数据
维普
