Hydrodynamics of Meander Bends in Intertidal Mudflats: A Field Study From the Macrotidal Yangkou Coast, China

作者：Chao Gao, Alvise Finotello, Andrea D’Alpaos, Massimiliano Ghinassi, Luca Carniello, Yupeng Pan, Dezhi Chen, Ya Ping Wang · 发表于：Water Resources Research · 年份：2022 · DOI：10.1029/2022wr033234 · 被引用次数：25 · 研究领域：Coastal wetland ecosystem dynamics、Coastal and Marine Dynamics、Geological formations and processes

Abstract Meandering channels are ubiquitous features in intertidal mudflats and play a key role in the eco‐morphosedimentary evolution of such landscapes. However, the hydrodynamics and morphodynamic evolution of these channels are poorly known, and direct flow measurements are virtually nonexistent to date. Here, we present new hydroacoustic data collected synchronously at different sites along a mudflat meander located in the macrotidal Yangkou tidal flat (Jiangsu, China) over an 8‐day period. The studied bend exhibits an overall dominance of flood flows, with velocity surges of about 0.8 m/s occurring immediately below the bankfull stage during both ebb and flood tides. Unlike salt‐marsh channels, velocities attain nearly constant, sustained values as long as tidal flows remain confined within the channel and reduce significantly during overbank stages. In contrast, curvature‐induced cross‐sectional flows are more pronounced during overbank stages. Thus, a phase lag exists between streamwise and cross‐stream velocity maxima, which limits the transfer of secondary flows and likely hinders the formation of curvature‐induced helical flows along the entire meander length. Our results support earlier suggestions that the morphodynamics of intertidal mudflat meanders does not strongly depend on curvature‐induced helical flows and is most likely driven by high velocities and sustains seepage flows at late‐ebb stages, as well as by other tidally‐mediated processes such as waves an...