弱潮型河道形态演化与河型判别方法：以黄河下游为例

Morphological evolution and pattern identification of weakly tidal river channels: A case study of lower reaches of Yellow River

摘要

【目的】弱潮型尾闾河道的形态演变机制复杂，厘清其在水沙作用下的响应规律对于河道治理与防洪安全至关重要。【方法】通过开展系统的物理模型试验，观测不同水沙条件下蜿蜒河道的动态演变全过程。基于试验揭示的机理，结合河流阻力理论，引入河道比降、弗劳德数及床沙粒径等参数，构建了河道形态特征参数。利用支持向量机(SVM)对黄河下游历史水文断面数据进行分类，建立了河型的定量判别标准，确定了游荡、分汊与弯曲河型的定量化判别阈值。【结果】试验结果表明，河道演变呈现“稳定→微变→强变”的典型三阶段规律。水沙条件主导演变模式，高流量引发强烈侵蚀与改道，而高含沙量则导致淤积与拓宽。利用最新河道资料验证表明，该河型判别标准能有效判别河型转变，如孙口—艾山段已呈现向分汊型发展的趋势，与遥感影像判读结果一致。【结论】研究证实，物理模型是揭示河道演变机理的有效手段。所构建的形态参数模型实现了从定性描述到定量判别的跨越，对河道治理具有理论指导意义。

Abstract

[Objective] The morphological evolution mechanism of weakly tidal estuarine channels is complex. Clarifying its response to runoff and sediment dynamics is crucial for river channel regulation and flood control. [Methods] Systematic physical model experiments were conducted to observe the complete dynamic evolution process of meandering channels under different runoff and sediment conditions. Based on the mechanisms revealed by the tests, and combined with river resistance theory, parameters including channel slope, Froude number, and bed sediment size were introduced to construct characteristic morphological parameters. Historical hydrological cross-sectional data from the lower reaches of the Yellow River were classified using support vector machine(SVM), and quantitative criteria for river pattern identification were established. [Results] The experimental result indicated that river channel evolution exhibited a typical three-stage pattern: stable, slight change, and strong change. Runoff and sediment conditions dominated the evolution mode, where high flow triggered intense erosion and channel avulsion, while high sediment concentration led to deposition and channel widening. Based on this, quantitative thresholds for identifying wandering, braided, and meandering river patterns were established. Validation using recent river channel data confirmed the effectiveness of these criteria in identifying pattern transitions. For instance, the Sunkou-Aishan section was identified as transitioning towards a braided pattern, which was consistent with interpretations from remote sensing imagery. [Conclusion] Physical modeling is an effective approach for revealing river channel evolution mechanisms. The constructed morphological parameter model facilitates the transition from qualitative description to quantitative discrimination, offering theoretical guidance for river channel management.

关键词

物理试验 / 阻力规律 / 河流形态 / 相对糙度 / 形态参数 / 支持向量机 / 泥沙 / 遥感

Key words

physical test / resistance pattern / river morphology / relative roughness / morphological parameters / support vector machine / sediment / remote sensing

基金资助

国家自然科学基金青年基金项目“过渡型蜿蜒河道的控制性水流特征与形态演变过程研究”(52409103)