Use of bottom slots and submerged vanes for controlling sediment upstream of duckbill weirs

Abstract

Duckbill weir is one of the water level control structures in irrigation networks, which is of interest to many engineers. Sediments transported in irrigation networks that accumulate upstream of duckbill weirs cause problems in operation, and affect the upstream water level. In this paper, submerged vanes and bottom slots are investigated for flushing the sediment downstream of the said weir. The experiments were conducted in a rectangular flume, 12 m long, and 0.6 m wide. The vanes placed in four sections were perpendicular to the sidewall. Flow-3D software was used for simulation of flow and sedimentation patterns. The results showed that submerged vanes create a secondary flow which is very useful for flushing the sediment, especially in the value of H p 0:33 (H is head over the sidewall and P is the weir height). Further, the results showed duckbill weir efficiency (which is defined as the ratio of sediment trap to flow capacity of the weir) is as high as 47% (for values of H/P Â 0.1-0.5 and total models). Finally, image processing results showed a maximum relative error of 14.4% for the simulation of the sediment pattern with Flow-3D software.