HYDRAULIC PERFORMANCE OF A SKEWED 2-STAGE FLOOD CHANNEL

This paper presents the results of an experimental investigation carri ed out in the UK Flood Channel Facility into the hydraulics of overban k river flow (two-stage channels), This large experimental channel can accommodate models up to 60 m in length. The topic investigated here concerns straight river channels flanked by skewed floodplains. Angles of skew over the range 2 degrees to 9 degrees and overbank depth rati os from 0.15 to 0.49 were studied. Friction characteristics are derive d from the measured stage-discharge curves and compared with the equiv alent straight (unskewed) two-stage channels as well as simple trapezo idal ones. Distributions of both transverse and longitudinal velocity components as well as bed shear stress are presented and discussed. In ferred secondary circulation systems in the deep channel are proposed and related to the measured hydraulic characteristics of the flow.