A dike-groyne algorithm in a terrain-following coordinate ocean model (FVCOM): Development, validation and application

A dike-groyne module is developed and implemented into the unstructured-grid, three-dimensional primitive equation finite-volume coastal ocean model (FVCOM) for the study of the hydrodynamics around human-made construction in the coastal area. The unstructured-grid finite-volume flux discrete algorithm makes this module capable of realistically including narrow-width dikes and groynes with free exchange in the upper column and solid blocking in the lower column in a terrain-following coordinate system. This algorithm used in the module is validated for idealized cases with emerged and/or submerged dikes and a coastal seawall where either analytical solutions or laboratory experiments are available for comparison. As an example, this module is applied to the Changjiang Estuary where a dike-groyne structure was constructed in the Deep Waterway channel in the inner shelf of the East China Sea (ECS). Driven by the same forcing under given initial and boundary conditions, a comparison was made for model-predicted flow and salinity via observations between dike-groyne and bed-conforming slope algorithms. The results show that with realistic resolution of water transport above and below the dike-groyne structures, the new method provides more accurate results. FVCOM with this MPI-architecture parallelized dike-groyne module provides a new tool for ocean engineering and inundation applications in coastal regions with dike, seawall and/or dam structures.