基于胡杨年轮重建黑河下游近100年春季径流量

在建立近100年来额济纳旗胡杨年轮年表的基础上,将标准年表(STD)的年轮宽度指数与黑河正义峡水文站径流量进行相关分析,结果表明年轮宽度指数与春季径流量负相关最显著,相关系数为-0.642。利用多元线性回归方程,重建了黑河下游(正义峡)近100年来的春季径流量,并用逐一剔除检验法进行了方程稳定性检验。统计检验参数表明估计序列与实测序列较为相近,残差缩减值RE和平均有效系数CE为0.419,乘积平均值t为4.949,符号检验超过95%的置信度,重建方程稳定可信。根据转换函数重建的近100年来春季径流量中,最大春季径流量为93.03m3/s,最小为37.99 m3/s。Morlet小波分析和功率谱周期分析表明,春季径流量存在3.3年的显著周期变化。

About 100-year reconstruction of spring streamflow based on tree rings in the lower reaches of Heihe River

Populus euphratica is a single natural arbor and the dominant plant species of Ejin Oasis in the lower reaches of Heihe River,Inner Mongolia,which has a major function of maintaining weak ecological balance.But few high-resolution researches have been carried out in this region yet.Based on principles and methods of dendrochronology,we sampled 40 tree cores of Populus euphratica in the west Ejin River and developed ring-width Chronology.To understand the hydrologic response of the radial growth of populus euphratica,simple correlation analysis was conducted between the STD tree-ring index and the monthly and period runoff data of Zhengyixia station in the lower reaches of Heihe River.The analysis result showed that there was the evident negative correlation(-0.642) between ring-ring index and the spring runoff.The correlation coefficient 0.642 above 95 percent confidence level was used to reconstruct an about 100-year runoff in the region.The correlation value 0.719,accounting for 51.7 percent variance in the instrument records,F-test values 10.961 and P-value 0.000 in the linear regression models were significant well beyond the 99 percent confidence level."Leave-one-out" method was used to estimate stability of regression function based on statistics between the observed and estimated series.The positive RE values and CE values signified predictive ability of the model,and the sign tests for both actual and estimated values were significant at the 95 percent confidence level.The maximum and the minimums spring runoff among the reconstructed series are 93.03 m3/s and 37.99 m3/a,respectively.Wavelet analysis suggested that there were high frequency variations in the runoff reconstruction and the frequency peak was found at 3.3 years above 99 % confident level,which revealed there was a 3.3-yearperiod in the spring runoff series.