Simulation of Estuarine Flooding and Dewatering with Application to Great Bay, New Hampshire

A finite element model for simulating tidal flooding and dewatering of shallow estuaries is described and applications to hypothetical embayments and to the Great Bay, New Hampshire estuary system, are presented. The model incorporates two-dimensional kinematic wave physics, with a porous medium beneath the open channel to incorporate the realistic drainage of dry elements on a fixed, high resolution mesh. The Galerkin method is used on simple linear finite elements and solved implicitly with iteration in time. Simulations of idealized channels conserve mass, display physically correct behaviour, and agree with applicable one-dimensional results. Solutions for Great Bay further illustrate the physics of tidal flat hydrodynamics, characteristic distributions of bottom shear stress and the influence of topography on the overall circulation in the region. Sediment transport implications are discussed.