The Saemangeum Reclamation Project, which could be created 28,300 ha of the enclosed area and 11,800 ha of the freshwater reservoir, was started in 1991 and the final closure for a sea dike of 33 km was constructed in April 2006. As a result, the inherent fluid flow properties surrounding artificial sea dike will be changed and it will be influenced in a factor of the risk for the adjacent water ecosystem. The two-dimensional hydrodynamic model used to assess the change of flow properties is Delft2D-Flow model. This model was calibrated and validated against the observed data and was run using various scenarios.