Nonlinear barotropic tides and bores in estuaries

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The propagation of tides from the coastal ocean into shallow estuarine waters often produces characteristic nonlinearly induced asymmetries of velocity and water level in time series. Until recently (Aubrey and Speer, 1985) a sound physical understanding of related phenomena has been difficult to obtain as flow field data are rare. Numerical studies usually model a single estuary only; the modeled parameter space is often limited. From the vertically averaged governing equations that include nonlinear terms and bottom friction, we deduce that three dimensionless parameters set the character of the barotropic tidal response for channel shaped estuaries. We then develop a time-dependent numerical model based on the method of Lax and Wendroff. We use the model to explore the response over a wide range of the three parameters. Tidal responses include damped waves, hydraulic regimes, and tidal wave breaking or bore development. Where field data are available in the case of the Conwy Estuary, UK, water level and velocity compare favourably with model prediction.DOI: 10.1034/j.1600-0870.1991.t01-2-00007.x
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