Author(s): Ryan P. Mulligan; Logan M. Ashall; Danika Van Proosdij; Emma Poirier
Linked Author(s): Ryan Mulligan
Keywords: Tidal currents; Suspended sediments; Numerical modelling; Marsh vegetation; Coastal circulation
Abstract: In this study we use a high-resolution numerical model to examine the tidal flooding and draining of muddy channels and vegetated salt marsh flats in Minas Basin, Bay of Fundy, by comparison with field observations. The Delft3D model is used to simulate the hydrodynamics and sediment transport using a horizontal domain composed of three grids that achieve the highest resolution in the salt marsh. The model uses a flexible-stem vegetation sub-model that parameterizes low marsh (Spartina alterniflora) and high marsh (Spartina patens) plants based on a force balance according to the stem diameter, stem height and plant density with spatial variability based on Lidar topographic surveys. The results indicate that strong shallow flows occur in the drainage channels at the onset of flooding and at the end of e bb that transport high concentrations of suspended sediment of 0. 2-0. 4gL-1. Including vegetation in the model causes flow over the marsh to be significantly dampened, re-directed into channels, and results in higher correlation with observations especially at higher marsh elevations. This work indicates the importance vegetation in controlling the hydrodynamics and sediment exchanges between salt marshes and tidal flats via tidal channel networks.
Year: 2015