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首页> 外文期刊>Catena: An Interdisciplinary Journal of Soil Science Hydrology-Geomorphology Focusing on Geoecology and Landscape Evolution >Hydrodynamic and geomorphic adjustments of channel bars in the Yichang-Chenglingji Reach of the Middle Yangtze River in response to the Three Gorges Dam operation
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Hydrodynamic and geomorphic adjustments of channel bars in the Yichang-Chenglingji Reach of the Middle Yangtze River in response to the Three Gorges Dam operation

机译：三峡坝上近长江宜昌 - 成玲峡桥梁渠道的流体动力学和地貌调整

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摘要

The evolution of channel bars in response to upstream damming has significant impacts on channel stability, navigation, and aquatic habitats. Here, the effects of the Three Gorges Dam (TGD) operation on downstream channel bars in the Yichang-Chenglingji Reach (YCR) were comprehensively analyzed using remote sensing images, cross-sectional profiles, and hydrological datasets. The morphodynamic adjustments of channel bars in the YCR were significantly different during the pre- and post-TGD periods (i.e., before and after the construction of the TGD). Specifically, the total area of channel bars did not exhibit any significant trend in the pre-TGD period, but displayed a significant reduction following the construction of the TGD, although the morphodynamic response of each sub-reach was different. The channel bars in the YCR were relatively stable in the pre-TGD period, but became more erodible in the post-TGD period. The length/width ratio (LWR) of the bars showed an overall increase trend during the whole period from 1992 to 2017, not changing before and after the dam construction. The water discharge that led to the greatest channel bars adjustment was 27,000-30,000 m(3)/s (corresponding to bankfull discharge) in the pre-TGD period and 15,000-18,000 m(3)/s (corresponding to the medium discharge that can submerge the surface of the bars) in the post-TGD period. In addition, the grain size of non-uniform sediment with the highest replenishment degree gradually reduced downstream; these finer sediments were the main sources of material for the channel bars in the YCR. Quantitative relationships between bars area, the most effective bar-forming discharge and suspended sediment load with the highest replenishment degree, were proposed based on the improved Delayed Response Model (DRM). Results indicate that geomorphic adjustments of channel bars in the YCR are closely related to the previous four-year flow and sediment regimes, implying a delayed response of the fluvial system to damming.
机译：响应上游坝体的沟道条的演变对信道稳定，导航和水生栖息地产生了重大影响。这里，使用遥感图像，横截面轮廓和水文数据集综合分析了三峡大坝（TGD）操作对宜昌 - 成钟达到（YCR）的下游通道条的影响。在TGD后和TGD后，YCR中沟道杆的形态学调整显着不同（即，在TGD的构建之前和之后）。具体地，信道条的总面积在TGD期间没有表现出任何显着的趋势，但在TGD的构建后表现出显着的减少，尽管每个次达的形态学反应不同。在TGD前期间，YCR中的沟道条相对稳定，但在后TGD期间变得更加易于侵蚀。条形的长度/宽度（LWR）在整个1992年至2017年的整个时期内显示出总体增加趋势，在大坝建设之前和之后，不会改变。导致最大通道条调节的排水量为27,000-30,000米（3）/ s（3）/ s在TGD期间的27,000-30,000米（相当于银行排放），15,000-18,000米（3）/ s（对应于培养基排放可以在TGD后时期淹没条形图）。此外，不均匀沉积物的晶粒尺寸最高的补充程度逐渐减少下游;这些更精细的沉积物是YCR中沟道棒的主要材料来源。基于改进的延迟响应模型（DRM），提出了条形区域，最有效的棒状放电和悬浮沉积物的定量关系，提出了最高的补充程度。结果表明，YCR中信道条的地貌调整与先前的四年流量和沉积物制度密切相关，这意味着河流系统对撞击的延迟响应。

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