The morphometric variation of islands in the middle and lower Yangtze River: A variational analytical explanation
The morphometric variation of islands in the middle and lower Yangtze River: A variational analytical explanation
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长江中下游岛屿形态变化的变分分析解释
DOI：
10.1016/j.geomorph.2016.03.004
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发表时间：
2016-05
期刊：
影响因子：
3.9
通讯作者：
Gerald C. Nanson
中科院分区：
文献类型：
--
作者：
Xiaofang Liu;He Qing Huang;Gerald C. Nanson
分支河流是由各种形状的岛屿组成的，本研究应用变分分析方法来解释特定基本形状的岛屿的形态。根据长江中下游的实测资料，建立了一个分汊河道的理论模型，该模型在单河道和双河道分汊河段之间交替，分汊河段的平面形状近似为三角形，其中一个分汊比另一个分汊长。模型河流的平衡条件来自于变分研究的基本关系的流量连续性，通道边界阻力，推移质输运，和能量守恒的anbranching河流。我们证明，当这样一个系统达到静止平衡的三角形平面形状的岛屿是由通过两个通道的水和沉积物的比例。我们还表明，较短的直通道需要更大比例的泥沙相对于其水的比例。为了使岛屿呈现流线型的形态，进入每个水道的水和沉积物排放比例之间的差异需要尽可能小。当水沙比例取不同值时，岛屿的流线形态变化范围较大。与长江中下游5个岛屿的实测形态比较，理论计算的岛屿长度与实测值的偏差<± 10%，具有显著的一致性。
Anabranching rivers are formed of islands of various shapes and this study applies a variational analytical approach to explain the morphology of islands of a particular basic shape. A theoretically modeled anabranching river is developed based on observations from the middle and lower Yangtze River, which alternates between a single channel and a two-channel anabranching reach with islands approximately triangular in planform such that one anabranch is longer than the other. The equilibrium condition of the model river is derived from a variational investigation of basic relationships of flow continuity, channel boundary resistance, bedload transport, and energy conservation in the anabranching river. We demonstrate that when such a system reaches stationary equilibrium the triangular planform of the island is determined by the proportions of water and sediment passing through the two channels. We also show that the shorter straight channel takes a larger proportion of sediment relative to its proportion of water. For the island to take a streamlined morphology, the difference between the proportions of water and sediment discharge entering each channel needs to be as small as possible. When the paired proportions of water and sediment discharge take different values, the streamlined morphologies of the island vary in a wide range. In comparison with the measured morphologies of the five islands located in the middle-lower Yangtze River, the theoretically determined lengths of the islands are remarkably consistent, varying from the corresponding field measurements by a range of <±10%.
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影响因子：
4.9
作者：
S. Tooth;J. Jansen;G. Nanson;T. Coulthard;T. Pietsch
通讯作者：
S. Tooth;J. Jansen;G. Nanson;T. Coulthard;T. Pietsch
DOI：
--
发表时间：
1948-06
期刊：
--
影响因子：
--
作者：
E. Meyer-Peter;R. Müller
通讯作者：
E. Meyer-Peter;R. Müller
影响因子：
2.3
作者：
H. Huang;G. Nanson;S. Fagan
通讯作者：
H. Huang;G. Nanson;S. Fagan
影响因子：
--
作者：
G. Parker;P. Wilcock;C. Paola;W. Dietrich;J. Pitlick
通讯作者：
G. Parker;P. Wilcock;C. Paola;W. Dietrich;J. Pitlick
影响因子：
5.4
作者：
Huang, He Qing;Nanson, Gerald C.
通讯作者：
Nanson, Gerald C.