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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Intra-event scale bar-bank interactions and their role in channel widening
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Intra-event scale bar-bank interactions and their role in channel widening

机译：事件内规模的酒吧银行互动及其在渠道拓宽中的作用

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Channel bars and banks strongly affect the morphology of both braided and meandering rivers. Accordingly, bar formation and bank erosion processes have been greatly explored. There is, however, a lack of investigations addressing the interactions between bed and bank morphodynamics, especially over short timescales. One major implication of this gap is that the processes leading to the repeated accretion of mid-channel bars and associated widenings remain unsolved. In a restored section of the Drau River, a gravel-bed river in Austria, mid-channel bars have developed in a widening channel. During mean flow conditions, the bars divert the flow towards the banks. One channel section exhibited both an actively retreating bank and an expanding mid-channel bar, and was selected to investigate the morphodynamic processes involved in bar accretion and channel widening at the intra-event timescale. We repeatedly surveyed riverbed and riverbank topography, monitored riverbank hydrology and mounted a time-lapse camera for continuous observation of riverbank erosion processes during four flow events. The mid-channel bar was shown to accrete when it was submerged during flood events, which at the subsequent flow diversion during lower discharges narrowed the branch along the bank and increased the water surface elevation upstream from the riffle, which constituted the inlet into the branch. These changes of bed topography accelerated the flow along the bank and triggered bank failures up to 20 days after the flood events. Four analysed flow events exhibited a total bar expansion from initially 126m(2) to 295m(2), while bank retreat was 6m at the apex of the branch. The results revealed the forcing role of bar accretion in channel widening and highlighted the importance of intra-event scale bed morphodynamics for bank erosion, which were summarized in a conceptual model of the observed bar-bank interactions. Copyright (C) 2015 John Wiley & Sons, Ltd.
机译：河道条和河岸强烈影响辫状河和蜿蜒河的形态。因此，已经极大地探索了条形成和堤岸侵蚀过程。但是，缺乏针对河床和河床形态动力学之间相互作用的研究，尤其是在短时间内。这一差距的一个主要含义是，导致中通道筋反复积聚和相关增宽的过程仍未解决。在奥地利的一条碎石河Drau河的修复段中，河道中段的坝体在不断扩大的河道中发展。在平均流量条件下，杆将流量引向堤岸。一个通道部分既显示了主动撤退的堤岸，又显示了正在扩展的中间通道条，并且被选择来研究在事件内时间尺度上条的增加和通道扩展所涉及的形态动力学过程。我们反复调查了河床和河岸地形，监测了河岸水文学，并安装了延时摄影机，以便在四个流量事件期间连续观察河岸侵蚀过程。在洪水事件期间，淹没了中间通道的水坝，结果表明该中间水坝会增生。在随后的较低流量排水过程中，水流分流使沿河岸的分支变窄，并增加了浅滩上游的水面高度，从而构成了分支的进水口。 。床形的这些变化加速了沿堤岸的流动，并在洪水事件发生后长达20天触发了堤岸的破坏。四个分析的流动事件显示出总的钢筋扩张，从最初的126m（2）扩展到295m（2），而在分支的顶点处，岸撤退为6m。结果揭示了条形积聚在河道拓宽中的强迫作用，并强调了事件内尺度床形态动力学对于河岸侵蚀的重要性，在观察到的条形-河床相互作用的概念模型中对此进行了总结。版权所有（C）2015 John Wiley＆Sons，Ltd.

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