汉江上游郧县辽瓦店全新世古洪水研究

以汉江上游谷地郧县辽瓦店全新世古洪水滞流沉积剖面为研究对象,对其进行了洪水沉积学和水文学研究,并对其粒度组成、磁化率、烧矢量等理化性质进行了测量。结果证明,辽瓦店(LWD)剖面中夹有典型的古洪水滞流沉积物(SWD),它记录了一次特大洪水事件。利用地层学方法确定该次洪水事件发生在AD100-300之间(东汉-魏晋时代之间)。根据沉积学和水文学原理恢复了古洪水的洪峰水位在159.80m,以此计算出洪峰流量为65 420m3/s。根据2011年9月19日汉江洪水洪峰水位痕迹高程并利用相同方法反推洪水流量,所获流量数据与实测数据误差小于1%。

Palaeoflood Study in Liaowadian Site of Yunxian County in Upper Reaches of Hanjiang River

The Holocene sediment profile was surveyed in detail and sampled systematically at the Liaowadian site on the first river terrace in the upper Hanjiang valley.Its sedimentological and hydrological characteristics were observed in the field.Particle-size distribution,magnetic susceptibility and loss-on-ignition were analyzed in laboratory.An integration of the results showed that the palaeoflood slackwater deposits of the profile are very typical,recording an extreme flood event that might occur during A D 100-300 according to stratification comparison.Based on flood level information recovered using sedimentological and palaeo-hydrological methods,the palaeoflood peak discharge could reach 65 420 m3/s.The methods were further validated by the reconstruction of the modern flood event(20110919),with a very low error less than 1%.