黄河“92.8”洪水来源及特性分析

Analysis on Water Source and Characteristics of August 1992 Flood Occurred in the Yellow River

1992年8月,黄河花园口站发生6260m^3/s的洪水,水位达94.33m,为有记载以来的最高水位,造成比较大的灾害,引起了人们的普遍关注。这次洪水系黄河中游多沙粗沙区的暴雨形成,整个降雨过程在时间、空间上高度分散,洪水过程较长,它具有以下显的特点:①洪峰小、水位高;②花园口洪峰流量较小浪底显著增大;③三门峡库区冲淤严重;④漫滩流量减小,传播时间延长。发生这些异常现象的根本原因是,本次洪水的含沙量大以及近几年河道淤积严重、河床明显抬高。

In August 1992, there is a flood occurred at Huayuankou station on the lower Yellow River with discharge of 6260 m^3/s. The discharge of the flood is not big. but the water level is as high as 94.33m which is the highest level since the recording, causing heavier disasters and bringing widely to people's close attention as well. The flood is formed by a rainstorm happened in heavy sediment and eoarse sand areas on the middle reaches of the Yellow River. It is highly dispersed in time and space and with longer duration during the whole process of precipitation. It has the following notable characteristics: ①small peaks with high water level; ②peak discharge at Huayuankou is repmarkably increased comparing with that at Xiaolangdi; ③the Sanmenxia Reservoir area is severely aggradated and deaggradated; ④bankful discharge is smaller and travel time is longer. The basic reason of these abnormal phenomenas is caused by hyper-sediment concentration, severe deposition of the channel and obviously increased the river bed.