Didier Bousmar

Velocity measurements in a concrete experimental channel representing a flood plain

river dynamic. It exhibits therefore a slight curvature, with an approximate radius 25m. The reference xyz is defined with x always parallel to the main channel centerline. The bed was cement covered, with different ridges orientation in the main channel and in the flood plain. The corresponding Manning roughness coefficients in the two separate subsections were nmc = 0.012s/m 1/3 in the main channel and nfp = 0.013s/m 1/3 in the floodplain. They were obtained by measuring water depths of flows passing in only one of the beds for various discharges. The mainchannel bank was 0.16m high, while its bottom width was Bmc = 0.7m. The bank slope equals 32° at the interface with the floodplain, whose width was Bfp = 2.17m. A stilling basin preceded the entrance of the compound channel, and the flow stilling was pursued by honeycombs of bricks and wire netting screens. At the downstream end of the channel, an inclined gate was used to set a constant water depth. Longitudinal evolution of the water depth in the main channel could be evaluated by three fixed point-gauges (Fig. 1).