辫状河流演变过程与机理的研究进展

A review on morphodynamic processes and mechanism of braided rivers

  • 摘要: 辫状河流属于冲积河流的主要类型,对流水地貌景观、水生栖息地和河流开发与生态保护具有重要科学意义。根据辫状河流演变过程与机理的国内外研究进展,对定义与形态特征进行综合描述,并给出常用的形态表征方法与参数。总结辫状河流的4种野外地形观测方法以及水槽试验和数值模型的应用,比较它们的适合范围;描述辫状河流的不同形态单元的组成,列举沙洲形成、汊道调整与横向迁移、岸滩侵蚀、河漫滩淤积等基本演变规律;对比分析水流功率、床沙粒径、泥沙补给、滨河植被、河谷宽度等影响辫状河流形态动力学过程的主要控制因素;指出青藏高原不同空间尺度辫状河流的形成原因、形态特征和演变规律是河流动力学的重要研究方向。

     

    Abstract: Braided river as a primary alluvial river pattern is of great importance on fluvial geomorphology, aquatic habitat, river exploitation and ecological protection. According to the literature review on braided rivers, the basic definition and morphological characteristics are described, and several classic methods and parameters of morphological characterization are introduced. In addition, field methods of obtaining high-precision DEM are summarized as well as the application of flume experiment and numerical model which advantages and disadvantages are pointed out, respectively. This paper describes the general composition of different morphological units of braided river, and lists the evolution mechanism of bar formation, anabranching adjustment and lateral migration, bank erosion and floodplain deposition. The primary controlling factors of morphodynamics and evolution of braided river, such as stream power, bed sediment particle size, sediment supply, riparian vegetation and valley width, are compared and analyzed. Meanwhile, a promising direction for alluvial river dynamics is to unravel formation causes, morphological characteristics, and fluvial processes of braided rivers with different spatial scales on the Qinghai-Tibet Plateau.

     

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