Department of Geosciences, University of Padova, Padova, PD I-35131, Italy.
Department of Civil, Environmental, and Architectural Engineering, University of Padova, Padova, PD I-35131, Italy.
Proc Natl Acad Sci U S A. 2018 Feb 13;115(7):1463-1468. doi: 10.1073/pnas.1711330115. Epub 2018 Jan 29.
The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths.
大多数潮流通道都呈现出明显的弯曲特征。尽管它们在油藏形成和潮流地貌形态方面非常重要，但仍存在一些问题，即潮流弯道的动力学是否可以用河流过程和理论来解释。关键的区别表明并非如此，例如周期性的景观形成潮流的反转，以及广泛接受的经验观念，即潮流弯道是稳定的景观特征，与它们迁移的河流弯道形成鲜明对比。相反，在这里，我们表明，一旦经过适当的归一化，观察到的潮流和河流弯道的迁移率非常相似。归一化的关键是潮流通道宽度的作用，它响应景观形成流速和潮流棱柱体的强烈空间梯度。我们发现，潮流弯道的迁移动力学与河流弯道演化的非线性理论一致。我们的结果挑战了将潮流通道视为稳定景观特征的传统观点，并表明由于潮流棱柱体在弯道波长上的大梯度，蜿蜒的潮流通道再现了许多河流弯道。
