NearshoreOffshoreModellen

NearshoreOffshoreModellen is a class of computational models designed to simulate coastal dynamics by integrating nearshore and offshore processes within a single framework. The approach aims to represent wave propagation, currents, water levels, sediment transport and shoreline morphology from the open sea to the beach and shoreline features.

Core idea: offshore and nearshore domains are connected so that physics computed in the offshore region influence nearshore conditions and vice versa. Offshore modules may simulate deep-water wave transformation and storm surge, while nearshore modules handle wave breaking, surf zones, friction, and alongshore transport. Models are coupled through shared boundaries, flux exchanges, and nested grids or multi-scale solvers, often using time stepping coordination to ensure consistency across scales.

Applications include coastal flood risk assessment, harbor and breakwater design, erosion and shoreline evolution studies, dune management, beach nourishment planning, and assessment of offshore wind farm interactions with sediment transport and wave loads.

Typical features include multidimensional hydrodynamics, wave- and tide-driven forcing, sediment transport and bed evolution, and sometimes wind fields and wave-structure interactions. Numerical schemes may employ depth-averaged shallow-water equations for the nearshore, phase-averaged or fully 3D models offshore, and morphological updating rules to update bed elevations. Data assimilation and calibration with field measurements are common.

Status: Nearshore–offshore coupling is an active area of coastal modelling. Several modelling systems support nearshore–offshore integration, using components such as SWAN, XBeach, Delft3D, TELEMAC, ROMS, or similar modules. Researchers apply these approaches to European and global coastlines to support planning and risk assessment.

Limitations include substantial data requirements for bathymetry and sediment properties, high computational costs for fine-scale, long-term simulations, and challenges in validating cross-domain morphodynamics due to scale differences and uncertain forcing.