HEC RAS模型在汉江上游郧县尚家河段全新世古洪水流量重建中的应用

以汉江上游郧县尚家河段含有4期全新世古洪水事件的沉积剖面为例，采用HEC RAS模型计算出这4期最大古洪水最大洪峰流量为45 550~61 750 m3/s，与比降法重建的古洪水洪峰流量结果相比，误差为158%~309%。同时，采用相同水文参数和模型，计算了剖面附近的2010年7月18日洪痕洪峰流量，与实测流量相比，误差为491%，说明重建古洪水洪峰流量时水文参数选择与洪峰流量计算结果是合理的，同时也表明利用HEC RAS模型在重建古洪水流量中简捷，可操作性强，其研究结果为古洪水水文学研究提供一种新的方法

APPLICATION OF THE HOLOCENE PALAEOFLOOD DISCHARGE RECONSTRUCTION USING HEC RAS MODEL AT SJH REACH IN THE YUN COUNTY IN THE UPPER REACHES OF THE HANJIANG RIVER

Four Holocene palaeoflood slack water deposits (SWD) were found at Shangjiahe reach in the Yun County of Hubei province in the upper reaches of the Hanjiang River. In the laboratory, the grain size distribution, magnetic susceptibility and loss on ignition were analyzed and compared with modern flood SWD, and the results indicated that four palaeoflood SWDs were typical and recorded four palaeoflood events in the upper reaches of Hanjiang River. The HEC RAS software was developed at the Hydrologic Engineering Center (HEC), which is a division of the Institute for Water Resources (IWR), U.S. Army Corps of Engineers. HEC RAS is an integrated system of software, designed for interactive use in a multi tasking, multi user network environment. The HEC RAS system contains four one dimensional river analysis components for steady flow water surface profile computations, unsteady flow simulation, movable boundary sediment transport computations and water quality analysis. A key element is that all four components use a common geometric data representation and common geometric and hydraulic computation routines. In addition to the four river analysis components, the system contains several hydraulic design features that can be invoked once the basic water surface profiles are computed. The system is comprised of a graphical user interface (GUI), separate hydraulic analysis components, data storage and management capabilities, graphics and reporting facilities. The maximum peak discharges of the four palaeoflood events were calculated from 45 550 m3/s to 61 750 m3/s using HEC RAS model. These calculated discharges were checked by the reconstructed palaeoflood peak discharges by the slope area method, and the errors were 1.58%-3.09%. At the same time, the flood peak discharge of July 18, 2010 extraordinary flood was also reconstructed with the same model and hydrographical parameters, and the error between the calculated and gauged discharges was about 4.91%. This result showed that it was reasonable to calculate palaeoflood peak discharges and choose hydrological parameters, and it was simple and easily operable to use HEC RAS model to reconstruct palaeoflood peak discharges. Moreover the study results provided a new method on the study of palaeoflood hydrology. Thus, the results effectively extended the upper reaches of the Hanjiang River flood hydrology data sequence and provided a reliable reference for engineering construction, flood control and disaster alleviation in upper reaches of Hanjiang River