3D DCSM-FM: a sixth-generation model for the NW European Shelf : 2022 release

Upon request of Rijkswaterstaat (RWS), Deltares has developed a sixth-generation hydrodynamic model of the Northwest European Shelf: the Dutch Continental Shelf Model - Flexible Mesh (DCSM-FM). This model is the latest in a line of DCSM models and a successor to the fifth-generation WAQUA model DCSMv6. Specifically, this model covers the North Sea and adjacent shallow seas and estuaries in the Netherlands, such as the Wadden Sea, the Ems-Dollard estuary, the Western Scheldt and the Eastern Scheldt. The development of the present model is part of a more comprehensive project in which sixth-generation models have been developed for all waters managed and maintained by RWS. An important difference with the previous fifth-generation models is the use of the D-HYDRO Suite, the new software framework for modelling free surface flows, which was first released in 2015 and allows for the use of unstructured grids. The present report describes the model setup and validation of the three-dimensional model 3D DCSM-FM. The main purpose of 3D DCSM-FM is to have a versatile model that can be used for all manner of studies and research on the Northwest European Continental Shelf, including the North Sea and adjacent shallow seas, such as the Wadden Sea. It aims to combine state-of-the-art capabilities with respect to modelling of water levels (tide and surge) as well as (residual) transport phenomena. The latter is crucial for application in water quality and ecological modelling. A first version of this model was released in 2020. In 2022, this model was updated with respect to model bathymetry, vertical layering, tidal boundary forcing and meteorological forcing and numerous other adjustments and improvements. These changes, including a renewed validation of water levels, salinity and water temperature, are reflected in this current report.