Modeling wetting and drying scheme based on an extended logarithmic law for a three-dimensional sigma-coordinate coastal ocean model

A wetting and drying scheme (WDS) is developed to incorporate into a three-dimensional sigmacoordinate coastal ocean model (POM; Blumberg and Mellor, 1983) with proposing an extended logarithmic profile within and above bed boundary layers to accurately simulate 3D hydrodynamics in extremely shallow coastal seas. While the WDS is simplistically formulated, it can selectively retain the computational robustness and water mass conservation in the domain. The developed model, WD-POM, is verified to have a good agreement with the analytical solution for non-linear long-waves propagating on a sloping beach proposed by Carrier and Greenspan (1958). WD-POM is also applied to a tidal simulation in San Francisco Bay, California, USA, which is encompassed by huge intertidal areas. The model-generated surface elevations and tidal currents are compared to the observed data-set by NOS-NOAA (2003) and demonstrate that WD-POM is capable of precisely reproducing the estuarine intertidal hydrodynamics in San Francisco Bay. The influence of intertidal topographies on estuarine hydrodynamics is next examined, by comparing between the simulated result with WDS and that without WDS. The wetting and drying process is represented to significantly alter development of tidal waves and a current field in San Francisco Bay. The intertidal sloping bathymetry appears to enhance refraction and shoaling of tidal waves propagating anticlockwise as Kelvin waves. The intertidal effects are evidently exhibited to modify the amplitude and phase speed of the tidal waves, and to shift the current direction to be shore-normal.