Complexity of the flooding/drying process in an estuarine tidal‐creek salt‐marsh system: An application of FVCOM

Abstract

The tidal flooding/drying process in the Satilla River Estuary was examined using an unstructured‐grid finite‐volume coastal ocean model (FVCOM). Driven by tidal forcing at the open boundary and river discharge at the upstream end, FVCOM produced realistic tidal flushing in this estuarine tidal‐creek intertidal salt‐marsh complex, amplitudes and phases of the tidal wave, and salinity observed at mooring sites and along hydrographic transects. The model‐predicted residual flow field is characterized by multiscale eddies in the main channel, which are verified by ship‐towed ADCP measurements. To examine the impact of complex coastal geometry on water exchange in an estuarine tidal‐creek salt‐marsh system, FVCOM was compared with our previous structured‐grid finite difference Satilla River Estuary model (ECOM‐si). The results suggest that by failing to resolve the complex coastal geometry of tidal creeks, barriers and islands, a model can generate unrealistic flow and water exchange and thus predict the wrong dynamics for this estuary. A mass‐conservative unstructured‐grid model is required to accurately and efficiently simulate tidal flow and flushing in a complex geometrically controlled estuarine dynamical system.