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| 1 | The mechanism of barrier river reaches in the middle and lower Yangtze River显示文摘在它人工地或自然地被扰乱以后,冲积隧道总是以沉积运输的平衡国家调整了自己。怎么维持沉积运输的平衡国家并且使河政体稳定总是是河的 geomorphologists 的担心。在长江的中间、更低的活动范围的隧道被区分的河和单个线的河的蹒跚的分发描绘。河政体的变化比在单个线的河里在区分的河里猛烈地是更多。区分的河里的河政体的调整是否能通过单个线的河并且宣传到下游的活动范围,影响全面的河政体的稳定性。研究证明障碍河活动范围能阻止宣传到下游的活动范围接近在上游的隧道调整;因此,它在稳定河政体起一个关键作用。这研究在长江的中间、更低的活动范围调查 34 个单个线的河活动范围。根据长江的中间、更低的活动范围的河的进程的系统的摘要,障碍河活动范围的控制因素被总结并且提取:平面形态学单个线、蜿蜒地流;没有流动偏斜,节点在河活动范围的上面或中间的部分散布了;水力的几何系数是不到 4;纵的坡度比 12 大,凹面河岸的泥土内容比 9.5% 大,并且床沉积的中部的直径比 0.158 公里大。从海军司烧方程,流动的弯曲半径的计算公式动态轴被推出,然后这些的角色在限制流动的迁居上控制因素动态轴和障碍河活动范围的形成被分析。当时,障碍河活动范围被看作这到隧道边界的限制力量的动态轴是的流动的迁居力量的比率不到 1 在不同流动层次下面。障碍河活动范围的机制是以便甚至当在上游的河政体调整时,这个活动范围的隧道边界能总是抑制流动的移植振幅动态轴并且在不同的在上游的河政体条件下面集中主要的流线的平面位置,提供相对稳定的到来的流动为下游的活动范围调节,从而阻止宣传到下游的活动范围接近在上游的河政体调整。 | YOU Xingying TANG Jinwu ZHANG Xiaofeng HOU Weiguo YANG Yunping SUN Zhaohua WENG Zhaohui | 2017 | Journal of Geographical Sciences2017，27，10： | 9 |
| 2 | The barrier river reach identification and classification in the Middle Yangtze River显示文摘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. | Jinwu TANG Chunyan HU Xingying YOU Yunping YANG Xiaofeng ZHANG Jinyun DENG Meng CHEN | 2019 | Frontiers of Earth Science2019，13，3： | 0 |
| 3 | Coarse and fine sediment transportation patterns and causes downstream of the Three Gorges Dam显示文摘Reservoir construction within a basin affects the process of water and sediment transport downstream of the dam.The Three Gorges Reservoir (TGR)affects the sediment transport downstream of the dam.The impound- ment of the TGR reduced total downstream sediment.The sediment group d≤0.125mm (fine particle)increased along the path,but the average was still below what existed before the reservoir impoundment.The sediments group d>0.125mm (coarse particle)was recharged in the Yichang to Jianli reach,but showed a deposition trend downstream of Jianli.The coarse sediment in the Yichang to Jianli section in 2003 to 2007 was above the value before the TGR impoundment.However,the increase of both coarse and fine sediments in 2008 to 2014 was less than that in 2003 to 2007.The sediment retained in the dam is the major reason for the sediment reduction downstream. However,the retention in different river reaches is affected by riverbed coarsening,discharge,flow process,and conditions of lake functioning and recharging from the tributaries.The main conclusions derived from our study are as follows:1)The riverbed in the Yichang to Shashi section was relatively coarse,thereby limiting the supply of fine and coarse sediments.The fine sediment supply was mainly controlled by TGR discharge,whereas the coarse sediment supply was controlled by the duration of high flow and its magnitude.2)The supply of both coarse and fine sediments in the Shashi to Jianli section was controlled by the amount of total discharge.The sediment supply from the riverbed was higher in flood years than that in the dry years.The coarse sediment tended to deposit,and the deposition in the dry years was larger than that in the flood years.3)The feeding of the fine sediment in the Luoshan to Hankou section was mainly from the riverbed.The supply in 2008 to 2014 was more than that in 2003 to 2007. Around 2010,the coarse sediments transited from depositing to scouring that was probably caused by the increased duration of high flow days.4)Fine sediments appeared to be deposited in large amounts in the Hankou to Jiujiang section.The coarse sediment was fed by the riverbed scouting,and much more coarse sediments were recharged from the riverbed in the flood years than in the dry years.5)In the Jiujiang to Datong section,the ratio of fine sediments from the Poyang Lake and that from the riverbed was 1:2.82.The sediment from the riverbed scouring contributed more to the coarse sediment trans- portation.The contribution was mainly affected by the input by magnitude and duration of high flows. | Songzhe LI Yunping YANG Mingjin ZHANG Zhaohua SUN Lingling ZHU Xingying YOU Kanyu LI | 2018 | Frontiers of Earth Science2018，12，4： | 0 |
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