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首页> 外文期刊>Frontiers of earth science >The barrier river reach identification and classification in the Middle Yangtze River
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The barrier river reach identification and classification in the Middle Yangtze River

机译：长江中游屏障河段识别与分类

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Adjustments of upstream river regimes are one of the main factors affecting downstream fluvial processes. However, not all adjustments of river regimes will propagate downstream. There are some distinctive river reaches where upstream and downstream adjustments have no relevance. However, the irrelevance is neither caused by different river types nor by the different conditions of water and sediment; but rather, the channel boundaries and riverbed morphologies block the propagation effect. These are referred to here as the barrier river reach phenomena. The migration of the thalweg line is the essential reason for causing the propagation effect. Numerous influencing factors for thalweg migration exist, including 1) the average flow rate above the critical bankfull discharge, the average flow rate below the critical bankfull discharge, and their ratio, 2) the ratio of the duration of the aforementioned two periods, 3) the thalweg displacement at the entrance of the river reach, 4) the deflecting flow intensity of the node, 5) the ratio of the river width to water depth, 6) the relative width of the floodplain, and 7) the Shields number. In this study, the correlativity between the measured distances and the restricting indicators of thalweg migration in the Middle Yangtze River over the years was established. The barrier degree of 27 singlethread river reaches was subsequently assessed. These reaches included 4 barrier river reaches; 5 transitional reaches transforming from barrier to non-barrier; 10 transitional reaches transforming from non-barrier to barrier; and 8 non-barrier river reaches. Barrier river reaches were found to be important for maintaining the stability of the river regime and the transverse equilibrium of sediment transport in the downstream reaches. To some extent, the barrier river reaches may protect the natural dynamical properties from being destroyed by artificial river regulation works. Thus, they are of great significance for river management.
机译：上游河流政权的调整是影响下游河流过程的主要因素之一。但是，并非所有河流制度的调整都会向下游传播。在一些独特的河道中，上游和下游的调整无关紧要。然而，无关紧要既不是由不同的河流类型引起的，也不是由水和沉积物的不同条件引起的。但是，河道边界和河床形态阻碍了传播效应。这些在这里称为障碍河到达现象。 thalweg线的迁移是引起传播效应的根本原因。存在许多影响thalweg迁移的因素，包括1）临界堤满流量以上的平均流量，临界堤满流量以下的平均流量及其比率； 2）上述两个期间的持续时间的比率3）河流入口处的thalweg位移； 4）节点的偏转流强度； 5）河流宽度与水深的比率； 6）洪泛区的相对宽度；以及7）Shields数。在这项研究中，建立了测得的距离与多年来长江中游海藻迁移的限制指标之间的相关性。随后评估了27条单线河道的屏障程度。这些河段包括4条屏障河段； 5个过渡阶段，从无障碍过渡到无障碍；从无障碍到障碍的10个过渡阶段； 8条无障碍河段。人们发现，屏障河段对于维持河流状态的稳定性和下游河流泥沙输送的横向平衡很重要。在一定程度上，屏障河段可以保护自然动力特性不受人工河道整治工程的破坏。因此，它们对河流管理具有重要意义。

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