渭河下游河段平滩流量的变化

平滩流量是河道主槽过流能力的一个重要指标,在河床演变学上具有重要意义。部分学者认为河段平滩流量更能反映整个河段的过流能力,然而,对于河段平滩流量研究范围及其影响因素的研究尚不多。本文以渭河下游咸阳-潼关河段为对象,研究河段平滩流量以及收敛长度的变化。断面平滩水位根据基于几何标准的WOL方法确定,河段平滩流量则采用收敛法估算。根据渭河下游河道长序列水沙过程的模拟分析发现,河段平滩流量与入口水沙条件呈现良好的相关关系,能很好地反应河道平滩特征的变化。同时,用于获得河段平滩流量的收敛长度与河道的冲淤变化密切相关,对实际估算河段平滩流量具有一定意义。

Analysis of bankfull discharge at reach scale in the lower Wei River

As an important parameter, the bankfull discharge is morphologically significant in the study of river morphology, sediment motion, flood dynamics and their ecological impacts. Previous researchers have pointed out that the determination of bankfull discharge is more relevant at river reach scale than at a local scale. Based on the geometry data obtained from the lower Wei River, in this paper we analyze the variation of bankfull discharge at reach scale (QBFR) in fluvial process. To identify the bankfull elevation of each cross section, we adopted a method of Wolman (WOL) that is based on the surveyed cross-sections and geometric criterion. The method of convergence was used to calculate QBFR. The analysis result indicates that the QBFR of this river reach is well correlated with its inflow discharge and sediment conditions. Besides, according to the length of convergence that depends on the fluvial processes, field observations of QBFR should be extended in order to improve its identification.