Assessment on Variations of Flow Velocity and Flood level of River and Estuary due to Vegetation

Vegetation along rivers is likely to play a role of roughness causing to increase river water level and flow velocity. During floods, floodwaters from the main channel overflow into the floodplain and increase the flow resistance due to the influence of vegetation, causing the flood level to rise. In case vegetation in rivers is formed near estuary, the flow resistance by vegetation may affect flow pattern along rivers. In this study, the characteristics of water level and flow velocity in rivers and estuaries that occur when a vegetation zone is located in a section about 1 km from the estuary were investigated by analyzing the results of numerical simulations. The aim of this study was to analyse the variability of water level and flow velocity in rivers and estuaries that may be caused by natural vegetation area in rivers or by planting as riverfront. Through numerical analysis using a two-dimensional numerical model, transverse flow analysis in a vegetated section and longitudinal flow analysis including an estuary of about 3 km were performed and their characteristics were presented.