Study of Seine bay hydrodynamics can't be separated from the Channel and continental shelf. The authors' modellings are aimed at the study of this global ladder and the insertion of coastal areas such as the Seine Bay in this context. Two 2-D models are used. One covers only the Channel, and the other from Pas-de-Calais to continental shelf limits including Celtic sea, Channel and southern North Sea. The results are comparated with long time current observations.