Concurrent correction method for modeling morphological response to dredging an offshore sandpit: Fid-Bau Portal

Concurrent correction method for modeling morphological response to dredging an offshore sandpit

Shi, Fengyan / Vittori, Giovanna / Kirby, James T.

Abstract In modeling the morphological impact of an offshore dredging pit using a process-based model, the hydrodynamic conditions, often derived from regional scale models and sometimes incomplete measurements, may not be in equilibrium with the initial bathymetry profile before dredging. This lack of equilibrium causes a fast profile adjustment toward an equilibrium, which may bias the model results representing the direct effect of the pit. In this study, a method is described which uses the parallel computing technique and evaluates only the morphological changes due to a single factor, i.e., the dredging of a pit. The hydrodynamics and morphodynamics are assumed to be in equilibrium before initial dredging of the pit. The morphological evolution is computed based on the change of sediment flux due to the presence of the pit. The model can avoid the computational demanding spin-up period necessary to reach equilibrium conditions. In particular the concurrent correction method is efficient for scenario testing with a large amount of morphological settings and hydrodynamic conditions.

Highlights • A new method is developed for modeling morphological change due to a single factor such as dredging a pit. • It is assumed that the morphological change only responds to the hydrodynamic change due to the presence of a pit. • This method gets rid of the effect of the uncertainties in given hydrodynamics on modeling of morphological change.