Numerical simulation of intertidal areas
Abstract
Our research is focused on the numerical simulation of water motion and morphodynamics in tidal systems. Morphodynamics, the study of how the bed changes over time due to erosion and deposition, is important for several reasons: the bedform geometry can influence flood risks, is important for vegetation and wildlife and affects which ships can pass. Using numerical models allows for proper ecological and economic management of these systems. As preliminary step in my research, the detailed tide-induced water motion in an intertidal area is investigated for a schematized tidal inlet system with a rectangular plan view and a linearly sloped bed, forced by a semi-diurnal lunar tide at the seaward boundary. The flow is governed by the 1D Shallow Water Equations. For the considered configuration, velocity peaks occur in the intertidal area during both flood and ebb. We compare the coordinate transformation method with other wetting-drying approaches, such as the removal/addition of grid cells used in Delft3D, the Defina approach with partially dry cells and perturbation methods. As a next step, we will focus more on idealized modelling: the use of simplified models based on first principles, where on the basis of scaling analysis the most dominant mechanisms can be selected and a perturbation method and harmonic analysis can be applied. The main advantage of these idealized models is their fast execution time, so that it is possible to thoroughly investigate the sensitivity for a range of parameters and identify equilibria and their stability.