论文部分内容阅读
以清代永定河芦沟桥志桩尺寸记录为骨干资料,结合近现代器测水文资料,使用分段建模的方法恢复了1766-2004年永定河芦沟桥断面的汛期径流量序列,序列表明永定河径流量在逐年尺度上具有极大的不稳定性,但其洪峰规模自19世纪以来不断减小,19世纪中期与20世纪初期是最为明显的丰水时段,而1920年代后径流量便明显萎缩,枯水期一直延续至现代。进入1920年代后,流量变化在18世纪后期至19世纪存在的30年准周期消失,水量变化呈现无周期特征。与太平洋年代际振荡指标PDO的比对发现,两者在30-40年尺度上具有明显的反相关关系,天然状态下,太平洋温度升高对应于永定河流域较为干旱的时段。海温异常造成的季风强度变化会导致华北地区降雨格局出现变化,进而影响到永定河芦沟桥以上河段的汛期水量,表明处于季风区北部边缘的永定河水系对于太平洋海温变动具有更大的敏感性。
Taking the records of the Lugou bridge pile in the Yongding River in the Qing Dynasty as the backbone data and the hydrologic data measured by the modern modem, the sequence of the flood season runoff at the Lugou Bridge section of the Yongding River from 1766 to 2004 was restored by the method of piecewise modeling. The sequence shows that Yongding River runoff has great instability on a year-by-year scale, but its peak size has been decreasing since the 19th century. The mid-19th and early twentieth century were the most significant wet-season periods, while the runoff was obvious after the 1920s Shrinkage, dry season has been extended to the modern. After entering the 1920s, the 30-year quasiperiodic cycle of flow changes disappeared from the late 18th century to the 19th century, and the change of water volume showed no periodicity. Compared with the PDO of the decadal oscillation in the Pacific Ocean, it is found that there is a significant inverse correlation between the two in the 30-40 year scale. Under natural conditions, the temperature rise in the Pacific corresponds to the drier period in the Yongding River basin. The variation of monsoon intensity caused by the anomalous SST can lead to the change of rainfall pattern in North China, which in turn affects the flood season water volume above the Lugou Bridge over the Yongding River, indicating that the Yongding River water system at the northern edge of the monsoon region has greater variations in the SST temperature in the Pacific Ocean Sensitivity.