Relationship between the equilibrium morphology of river islands and flow-sediment dynamics based on the theory of minimum energy dissipation |
| |
| Authors: | Xuhai Yang Zhaohua Sun Jinyun Deng Dongfeng Li Yitian Li |
| |
| Institution: | 1. State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China;2. Department of Geography, National University of Singapore, Kent Ridge 117570, Singapore |
| |
| Abstract: | River islands are vital geomorphic units in alluvial rivers, and the variation of their morphology and position plays a significant role in regulating flow-sediment transport and channel stability. Based on the theories of minimum energy dissipation theory of fluid movement and river morphodynamics, this study uses the river islands in anabranching channels to analyze the relationship between the shape coefficient of river island and the flow-sediment dynamics under stable equilibrium conditions. Results indicate that the river islands could adjust their lengths and widths to reach an appropriate allocation of flow diversion ratio and sediment separation ratio in the two anabranching channels to ensure flow-sediment being smoothly transported downstream and achieve the minimum energy dissipation. Under the minimum energy dissipation condition of flow-sediment transport balance, the ratio of “sediment separation ratio” to “flow diversion ratio” in short and straight branching channels is between 1 and 1.1. When the proportion of flow-sediment transport reaches its maximum, the steady island morphology coefficient is approximately 0.2; that is, the island length is five times the width. We verify the steady island morphology coefficients using two typical islands in the middle and lower reaches of the Yangtze River and find the relative error is within ±3%. |
| |
| Keywords: | Equilibrium morphology of islands Flow-sediment dynamics Minimum energy dissipation theory Sediment separation ratio Flow diversion ratio |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
