A finite element circulation model for embayments with drying intertidal areas and its application to the Quoddy region of the Bay of Fundy

A three-dimensional, triangular-mesh, finite element model has been adapted to allow for the flooding and drying of intertidal areas. The new algorithm sets velocities in dry areas to zero and removes elements from the computation when they are completely dry. Model tests simulating an idealized sloping beach that includes a tidal pool and a narrow deep channel laterally bounded by shallow drying sides, give qualitatively reasonable results. A simulation of the Quoddy region of the Bay of Fundy also gave good results when calibrated against available observations. This region includes extensive intertidal flats, tidal pools and channels that are blocked at low water by emerging shallows. The model is a clear improvement over a three-dimensional linear model and a fully nonlinear model without the drying routines using the same model grid. The drying model reproduces the tidal elevations with higher accuracy and has more realistic tidal currents.