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极端洪水是驱动河口地貌演变的关键自然动力，然而人类长期改造如何定量调控这一过程，学界尚缺清晰评估。2020年长江口洪水峰值流量、水位虽与1998年接近一致，但其引发的地貌调整幅度却显著减弱。高精度水深测量显示，2020年洪水期间深槽冲刷量较1998年减少39.5%，浅滩淤积量下降37%。基于水文数据、长序列潮汐记录及数值模拟的归因分析表明，响应衰减不仅与洪水历时缩短、累积洪量减少以及18.6年天文大潮周期导致的潮动力减弱有关，更主要归因于20多年来的河口工程干预及流域水库运行导致的来沙量减少。其中来沙量减少塑造了河口由整体淤积向冲刷模式转变的大背景；河口工程则通过约束洪水归槽、抑制漫滩水流调整泥沙分配，发挥出“促淤固滩、稳定河势”的作用，使地貌系统呈现“滩淤槽冲”的响应模式，从而逐渐优化河势，稳定滩槽格局，大幅降低极端洪水下的地貌演变幅度。本研究阐明了人类活动如何改变长江口动力地貌机制，从而显著削弱了极端洪水对河床的调整作用。研究成果不仅为归因全球河口洪水效应提供了普适框架，也为制定应对水文极端事件、增强河口韧性的工程策略奠定了科学基础。
Abstract：Extreme floods are critical natural drivers of estuarine geomorphic evolution. However, how longterm human modifications quantitatively regulate this process remains poorly understood. Although the 2020 flood in the Yangtze Estuary exhibited peak discharge and water levels comparable to the 1998 event, the resulting geomorphic adjustment was significantly reduced. High-resolution bathymetric surveys indicate a 39.5% reduction in deep-channel scouring and a 37% decline in shoal deposition during the 2020 flood. Attribution analysis, integrating hydrological data, long-term tidal records, and numerical modeling, reveals that this dampened response stems not only from shortened flood duration, reduced cumulative flood volume, and weakened tidal dynamics(associated with the 18.6-year nodal cycle), but more critically from reduced sediment supply driven by upstream reservoir operations and over two decades of estuarine engineering. While reduced sediment supply has shifted the estuary's baseline state from net accretion to erosion, estuarine engineering has stabilized the river regime by confining flows to the main channel and inhibiting overbank flow. This promotes a “shoal accretion and channel scouring” pattern, thus optimizing the river regime, stabilizing the shoal-channel configuration, and significantly reducing geomorphic changes during extreme floods. This study clarified how human activities altered the morphodynamic mechanisms of the Yangtze Estuary, significantly weakening the bed adjustment induced by extreme floods. These findings provide a general framework for attributing flood impacts in estuaries worldwide and offer a scientific basis for engineering strategies to enhance resilience to hydrological extremes.
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基本信息:
中图分类号:TV122;P931.1
引用信息:
[1]王晓光,何厚军,安东,等.人类改造下河口地貌对洪水响应衰减机制及归因分析[J].中国水利,2026,No.1034(08):1-10.
基金信息:
水灾害防御全国重点实验室开放基金项目“长江口地貌演变主控因子及驱动机制研究”（2025491811）
2026-05-06
2026-05-06
2026-05-06