1766～1911年黄河中游汛期水情变化特征研究

根据1766～1911年万锦滩汛期涨水情况的历史文献记录,重建研究时段内黄河三门峡断面逐年汛期流量R(109m3/a)和汛期开始时间T(侯尺度),其平均水平分别为径流量R=51.06×109m3/a,汛期开始时间T平均情况为7月上旬(7月第2个侯),对应于梅雨结束平均日期。研究时段内,1840 s前流量平,汛期开始时间总体较稳定;1840～1850 s流量普遍偏丰,汛期到来偏晚;1860 s开始流量减少,汛期提前,此阶段持续约40 a左右,是近300 a中黄河中游产流微弱持续最长的1个时期。

Hydrological Changing in the Middle Reaches of the Huanghe River During Flood Seasons of 1766-1911

Climate change and regional development under the background of water resource decreased over the Yellow River basin,which is under the monsoon climate control.The runoffs during flood season in the Yellow River is about 60%-70%.Rain-fed agriculture is the most important ecnomy part of China during the past thousands of years,while rainy summer and autumn leads to rivers flood,so in history Chinese government must predominate the flood to avoid the agricultural loss.According to the historical records of water level in the Wanjintan during 1766-1911 A D,the reconstruction of the flood flow(R) of Sanmenxia section sequences,and the start time of 115-year flood.Its multi-year average runoffs are R=51.06×109 m3/yr,and the average flood conditions for the start time T is in the early July.Wavelet shows the a 50-year cycle in the runoff series.The results show that: the runoffs in the middle reaches of the Huanghe River has inter-annual and inter-decadal oscillations like 6-8 years,quasi-22 years and 50 years.The determination of the quasi-22 years is link to the changing of Wolf Sunspot Numbers.The solar activity was significant during the 1830s.ENSO event is negative with the changing of natural runoff at the inter-annual scale.There was a low-flow period in the last 4 eras of LIA,and it has been the longest low-flow period since 1766 A D.The summer is the key reason of the changing of flood season beginning time for the unstable rainband moving from the middle and lower reaches of the Changjiang River to the middle reaches of the Huanghe River.Based on water level of Wanjintan in the middle reach of Yellow River(Sanmenxia,Henan)in the 1766-1911s were recorded the time of rising water.Under the 5-days scale,establishing the beginning time of flood season in Sanmenxia in the study period.The results show that: 1766-1840s is the start time of flood season in the middle reaches of the average level;in 1840-1860s the beginning time of flood season come late;in 1860～1890s the beginning time of flood season advance again.In the study period,the average beginning time of flood season in the middle reaches of Yellow River is in the early July,the end time of rainy in the middle reach of Changjiang River have a good correspondence.However,summer wind rain-band moving is the main driving factors of changing of flood season beginning.The delay of flood season to about one pentad in the middle reaches of the Yellow River from 1870 to 1900 is in accordance with the relative low temperature of the Loess Plateau in summer,while the early flood season of the middle reaches of the Yellow River and Qin River is correspondent with the relative high temperature of summer in the Loess Plateau.