제방의 의한 새만금주변의 순환

Abstract

Saemangeum is a macrotidal zone located at the southwestern part of Korea. Between 1992 and 2006, a series of 33km long tidal dykes surrounding the Mankyung and Donjin riverine estuaries and intertidal zones were constructed. The dykes fasten the tidal phase, weaken the tidal current and lower the tidal amplitude. The dykes resemble an inequality sign open toward the east and can be divided into southern and northern legs, and the effects of dykes are greater in front of the southern leg. Using a finite volume coastal ocean model (FVCOM), we explain how the dykes modify the tide. Before the dykes were built, the tide was refracted by the coast and the co-phase became parallel to the coast line. The southern leg was placed parallel to the co-phase line and it is very effective in blocking the tidal energy propagating toward the west coast of Korea, and weakens the tidal current. A simple scaling analysis shows that before the dykes were built over the area the southern leg was placed, in the direction normal to the leg in which the tidal amplitude varies the non-linear advection of momentum, frictional dissipation and pressure gradient balance. Once the tidal flows weakened, so do the momentum advection and friction. The pressure gradient, then, becomes smaller reducing the tidal amplitude. The northern dyke was built oblique to the co-phase line. Only the component normal to the leg wa