Experiments on Flood-Wave Propagation in Compound Channel

Abstract

Data related to floodplain inundation by fast-rising floods are limited and needed. Eighteen data sets are provided from experiments conducted in a symmetrical compound channel that has a trapezoidal main channel. Three flood types were investigated: long, moderate, and short duration floods (LDF, MDF, and SDF). The data include water depths, velocities, and bed shear stresses measured in straight and meandering reaches. Data show that a flat portion occurred in the MDF and LDF hydrographs when the floodplain was being inundated. Flood peaks stretch exponentially along the channel and are more pronounced in the meandering reach. An SDF has the fast decay rate, followed by MDF and LDF. Overbank front speeds of the SDF and MDF can be predicted by the moving speed of a surge, with the surge height being the difference of the bankfull depth from that of the base flow. The tail of a synthetic hydrograph should be modified according to the channel storage so that it can be used as an inflow boundary condition.