Overbank Flow with Vegetatively Roughened Flood Plains

An experimental and theoretical investigation into the flow characteristics of channels with complex cross sections was undertaken. In this study, particular attention was given to the problem of non‐submerged flood‐plain roughnesses. This differs from previous studies in which compound‐channel flow was primarily investigated for more or less uniform boundary roughnesses. In order to achieve more conformity with natural rivers, the flood plain and the main channel were separated in the model by a sloping bank. Two cross sections with varying aspect ratios and flood‐plain roughnesses were investigated. The necessary measurements were carried out by applying LDV and Preston‐tube techniques. On the basis of simple turbulence assumptions methods are presented by which the flow resistance in vegetatively roughened flood plains and main channels can be properly predicted as a function of independent and directly determinable basic flow parameters. A first verification of this model was accomplished using field ...