A coupled modeling scheme for longshore sediment transport of wave-dominated coasts—A case study from the southern Baltic Sea

A modeling scheme based on dynamic coupling of a high-resolution 1D cross-shore model to a 2DH area model is developed to calculate the total longshore sediment transport (LST) rate in wave-dominated coasts. The purpose of this coupling strategy aims at resolving the LST with a high-resolution (both temporally and spatially) inside the surf-zone and with a coarser spatial resolution seaward of the surf-zone. The 2DH area model operates on a fixed pre-designed regional grid (parent grid) and the 1D cross-shore model is dynamically coupled to the boundary of the parent grid with a time-varying domain, starting from the first wave breaking point and ending at the maximum wave set-up point. The time-varying domain is generated in the 1D model by resolving the landward wave propagation from the offshore conditions provided by the 2DH area model at every time step. With a high-resolution cell size the 1D model resolves the wave propagation processes and resulting LST along the profile. The coupled model is applied to study the LST in the Pomeranian Bight at the southern Baltic Sea. Simulation results are compared with three other different hierarchical modeling methods (from empirical formulas such as CERC and Kamphuis to a 2DH area simulation). The comparative study indicates that the dynamically coupled model can be a reliable tool in practical applications, especially for the areas where hydrodynamics is controlled by complex bathymetry (e.g., multiple longshore bars) or morphologically induced circulation patterns.

► We proposed a dynamic coupling scheme for modeling of longshore sediment transport (LST).
► Comparison of performance on prediction of LST by different hierarchical models is given.
► The dynamic coupling scheme successfully predicts the erosion/deposition along the coast.