Bed Configurations of Downstream Sharp Crested Weir with Orifices

Abstract

Weirs are utilized for measuring of discharge, diminishing the water slope in canals and dissemination of water between canals for irrigation, etc. Classical sharp crested weir is associated with increases in turbulence and bed problems in downstream resulting in scouring activity that is considered one of unfavorable processes which dangers the general steadiness of the weir. Sharp crested weir with orifices along these lines introduces the same functions of the classical type but with has the capacity for minimizing changes in downstream bed configurations. An experimental study was conducted to predict and evaluate the geometry of bed configurations downstream of a sharp crested weir equipped with rounded orifices. Ninety nine (99) experimental runs were conducted. 11 weir models, 3 discharges, and 3 tail water depths. The utilized models referred to 11 scenarios for orifices schedules presented in terms of numbers and locations. 9 symmetrical orifices, 3 cm distance across each were made in the utilized weir to pass on much water in the downstream heading. The orifices were orchestrated in 3 equals spaced rows and 3 equal spaced columns. The study reach secured 4m length downstream the weir. Results were analyzed and graphically displayed. The geometry of bed configurations due to flow over the weir with orifices were contrasted with those of the classical sharp crested weir. Quantitative volumes assessments of local scour and silting utilizing the 11 scenarios were likewise introduced. Large contrasts between tested cases were reported.