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通过对汉江上游的野外考察,在湖北郧县段河谷发现了含有典型的古洪水滞流沉积物的全新世风成黄土土壤剖面。对该剖面采集样品,进行了沉积学分析,并且应用光释光技术中的单片再生剂量法(SAR)测定获得其OSL年龄,结合地层对比和文化层考古学断代,确定由古洪水滞流沉积层记录的特大洪水事件发生在距今1 800～1 700a之间,对应于我国历史上的东汉至魏晋时期(A.D.200～300)。通过与汉江上游地区、国内和世界各地的多种指标气候变化记录的对比分析,揭示出特大洪水事件发生在东汉至南北朝时期的气候恶化期。由于气候状态不稳定,降水变率大,致使严重地干旱和特大洪水皆有发生。该成果对我们深刻理解区域水文系统对于全球变化的响应规律具有重要意义。
Through the field investigation in the upper reaches of Hanjiang River, the section of Holocene aeolian loess with typical paleo-flood stagnant sediments was found in the section of Yunxian section of Hubei Province. Samples were collected from this section and analyzed by sedimentology. OSL ages were determined by single-site regrowth dosimetry (SAR) in photosoluminescence technique. Based on stratigraphic correlation and cultural-layer archeology dating, The catastrophic flood events recorded in the sediments ranged from 1,800 to 1,700 years ago, corresponding to the period from the Eastern Han Dynasty to the Wei-Jin Dynasties in China’s history (AD200 ~ 300). Through the comparative analysis of climate change records with many indicators in the upper reaches of the Han River, at home and in the world, it reveals that the catastrophic period of the severe flood occurred in the period from the Eastern Han Dynasty to the Northern and Southern Dynasties. Due to the instability of the climate and the large precipitation variability, severe droughts and catastrophic floods have taken place. This achievement is of great significance to our deep understanding of the response of regional hydrological systems to global changes.