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

[ 1] 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.