Experimental study on scours downstream of floodgates

The river reach downstream of a floodgate at the estuary of the Xinyihe Riv er is about 1.3km long, and the riverbed is composed of clotty clay. In the experiment, soil samples are taken from the construction site, and the inc ipient velocity is determined in a laboratory flume, and it is used to desi gn the scour model and to select model sand material. The experimental resu lts show that scours below the floodgate is unavoidable due to large discha rge and Low tidal level. Scours is caused by two factors: the rapid flow pa ssing though the floodgate and the water drop near the river mouth during l ow ride, and the scout below the floodgate is more critical to the structur al design. It is suggested that anti-scour walls should be used instead of riprap. The ideas and methods adopted in the experiment can be used as refe rence in the study on river scout under similar conditions.