汉江上游晚冰期以来古洪水事件发生的气候背景分析

古洪水事件是地表水文系统对极端性气候突变的响应。通过收集和整理汉江上游古洪水水文学研究成果，发现汉江上游T1阶地前沿的黄土-古土壤沉积剖面中记录了晚冰期以来10期古洪水事件，分别发生在12 600~12 400、11 500~11 400、 9 000~8 500、8 500~8 400、7 500~7 000、5 500~5 000、4 200~4 000、3 200~2 800、1 900~1 700和1 000~900 a BP。与国内外气候变化研究的成果对比分析，表明汉江上游发生的这10期古洪水发生时期，正好对应末次冰期晚冰期以来全球气候突变或转折期，说明汉江上游古洪水事件是对气候突变的响应。此研究结果对深入了解我国半湿润地区河流水文系统与气候变化的相互作用具有重要意义。

Climate Background about the Palaeoflood Events since Lateglacial Epoch in the Upper Reaches of Hanjiang River,China

The palaeoflood event is the response of the surface hydrological system to extreme climatic change. The study results of the palaeoflood hydrology research in the upper reaches of the Hanjiang River are integrated in this paper, and many loess-paleosol profiles recorded palaeoflood events at the frontier of the T1 terrace land in the upper reaches of the Hanjiang River are summarized. Ten episodes of palaeoflood events have occurred in the upper reaches of the Hanjiang River since the lateglacial, which were estimated to 12 600-12 400 a BP, 11 500-11 400 a BP, 9 000-8 500 a BP, 8 500-8 400 a BP, 7 500-7 000 a BP, 5 500-5 000 a BP, 200-4 000 a BP, 3 200-2 800 a BP, 1 900-1 700 a BP and 1 000-900 a BP respectively. Combined the ages of the palaeoflood events with the results of different proxies of climatic change research at domestic and abroad, it is indicated that the ten episodes of palaeoflood events in the upper reaches of the Hanjiang River were coincided with the period of global climatic instabilities or transitions since the lastglacial, these illustrate that the palaeoflood events are responses to climatic change in the upper reaches of the Hanjiang River. The upper reaches of the Hanjiang River is located in the southern part of China's north-south transition zone and its ecological environment is fragile. The river basin environment is very sensitive to climatic change. The Hanjiang River has undergone any major changes in the frequency and scale of river floods caused by climatic change, which will have an impact on the agriculture and economic prosperity of the Hanjiang River. The study results provide scientific basis and are of great significance in understanding the interaction between river hydrological system and climatic change in the upper reaches of the Hanjiang River and semi-humid area of China.