Simplified procedure for design of long-throated flumes and weirs

Abstract

An appropriate critical-depth measuring device should match the flume to approach channel conditions to provide a suitable Froude number in the approach channel to pass the sediment and for producing a stable and readable water surface at the gauging station. In current research, area ratio is explicitly expressed via an elegant equation. This equation is used to design the rectangular-throated flumes and weirs based on the upstream Froude number (upstream flow conditions). Introducing a correction factor, Cf, the proposed equation can be also used with high accuracy for nonrectangular control sections such as triangular (Cf=0.979) and parabolic/trapezoidal (Cf=0.987) sections. Moreover explicit equations for approach velocity coefficient of the long broad-crested weirs (long-throated flumes) are also presented. These relationships facilitate the discharge computation of the broad-crested weirs and long-throated flumes. The relations presented in this study will be useful in the design and analysis of the long-throated flumes and weirs, and reduce computation time and effort.