A High-Resolution Unstructured Grid Finite Volume Model for Currents Around Narrow Straits of Matsushima Bay

Matsushima Bay is one of the famous cultivation area of oysters. However, it is reported that the seedling collection decline in 2013. It is necessary to clarify this cause in order to take a countermeasure. There is some possibility that strong tidal currents through narrow straits cause oyster larvae in the bay to flow out. It is pointed out that increase of river discharge leads to a large flow of them. This research aims to clarify the influence on the movement of larvae in Matsushima Bay, especially focused on currents and river discharge. In this paper, the numerical model for tidal currents around Matsushima Bay is developed as the first step of the study to clarify their influence on them. The model is based on finite volume method with unstructured grid system and generalized terrain-following coordinate system (FVCOM). The model reproduces the influence on tidal currents by heat flux, precipitation, evaporation, surface wind stress and river discharge. The results are compared with some observation data to verify the validity of the model. The characteristics of currents around Matsushima Bay are also investigated from the result reproduced by the model, focused on the influence of fresh water from rivers.