A new semi-unsteady sand transport formula in GAIA

The numerical morphodynamic model GAIA predicts bed changes due to hydrodynamics by means of empirical sand transport formulae. The physical transport processes in the near shore, particularly the wave related processes, which are important during storms, are still poorly represented by the majority of the available transport formulae. Wave related processes become important in shallow waters, where currents are relatively small and waves undergo shape changes. As a consequence of the lack of wave related processes in the sand transport formulae, sand bar formation and migration cannot be modelled yet in TELEMAC. To address this, wave related transport processes were implemented in GAIA using the semi-unsteady sand transport formula of [11], known as the SANTOSS formula. The novelty of this formula, compared to other existing sand transport formulae in GAIA, is that SANTOSS calculates the sand transport rate accounting for wave non-linearity without the need of a phase-resolving wave model. The formula, implemented in a fully coupled 2D model (TELEMAC2D-TOMAWAC-GAIA), was tested against in situ measurements, showing good agreement with the measurements