古洪水行洪断面面积的估算

Palaeoflood Channel Cross Section Area Estimates

根据中国四大江河（ 长江、黄河、海河、淮河） 古洪水研究的成果，提出了在冲淤变化型河床上进行古洪水行洪断面面积估算的方法，即将估算的断面面积分为三个部分：现代均衡断面面积、古洪水均衡断面面积和次洪水冲刷断面面积．应用结果表明，次洪水冲刷断面面积往往占总过水断面面积的比重较大。

To obtain a palaeoflood discharge based on the pinch outs of its slackwater deposits,the palaeoflood channel cross section area is required.Overseas palaeoflood research is limited in valley type rivers.After the research work on the four largest rivers(Yangtze River,Yellow River,Haihe River,Huai River)in China,a method is present for the estimation of the cross sectional area of the allavial stream.The area is divided into three parts:the present mean cross sectional area,the difference between the present cross sectional area and the sectional area for the year of occurence of the palaeoflood,and the difference between the present mean cross sectional area and the maximum area of the erosion section.The conclusion is drawn that the third part is larger than the second part.