Abstract
This study is concerned with lateral exchange of flood water between the flood plain, where a banking structure exists, and river channel, due to breach flows from river channel as well as return flows of flood water. The study is directed toward the examination of lateral exchange of flood water simultaneously occurring in a plurality of river channel. It is demonstrated that a proposed numerical model, that comprises the finite volume method based on unstructured grid using flux-difference splitting (FDS) technique and numerical method to solve simultaneously flows in a channel and inundation flows in a flood plain along with appropriate boundary conditions is effective to simulate the above mentioned complex lateral exchange of flood water.