基于河道控制断面选取的山洪成灾流量修正

在山洪灾害分析评价工作中,采用不同河道断面作为控制断面时,根据曼宁公式计算的相应于成灾水位的成灾流量存在较大差异,对此提出了利用水力半径对水位流量关系进行修正的方法。通过取不同控制断面水力半径平均值,利用各个控制断面的湿周,得到修正后的控制断面面积,进而计算出修正后的流量,取各个断面修正后的流量均值或最大值作为计算成果。利用能量法计算了河段的平均流量,并与修正后的成灾流量进行对比。以湖北省宜昌市桥边镇桥边河河段和该镇松门溪河段为例进行了流量对比分析。两河段修正后的成灾流量分别为739.1 m~3/s和94.6 m~3/s,与能量法得到的成灾流量接近,表明根据水力半径对流量修正的方法具有一定的合理性。

Adjustment method of mountain torrent disaster discharge based on selection of control sections in river channel

Since the different selection of control sections may cause disparity in mountain torrent disaster discharge corresponding to the disaster water level calculated by Manning formula, so the method of adjusting level-discharge relation by hydraulic radius is proposed. The method used wetted perimeter of several control sections to adjust the cross-sectional areas and discharges through the average of the hydraulic radii. The adjusted average or maximum discharge at each section is used as the result. The mean discharge is calculated by energy method and compared with the adjusted discharge. Taking the reaches of Qiaobian River in Qiaobian town and Songmen Brook in Shangfengjian village in Yichang, Hubei Province as example, the adjusted discharges are 739.1 m3/s and 94.6 m3/s respectively, which are closed to 877.3 m³/s and 101.1 m³/s calculated by the energy method. The results show that the adjusted discharge based on the hydraulic radius is reasonable.