Spatially Varied Open-Channel Flow with Increasing Discharge Equation

Abstract

Flow visualization techniques and velocity measurements of jets in crossflow prove that the jet follows a distinct trajectory as if immiscible with the cross stream. Such observations reveal similarities between open channels receiving lateral inflow and vegetated flows. In the latter, the vegetation effect is accounted for as an increase in resistance, represented by a drag force. Using a similar approach, a new equation accounting for drag is developed for spatially varied flow (SVF) with increasing discharge. Experimental water surface profiles (WSP) from a number of studies with different arrangements of SVF were used to validate the performance of the proposed equation. A sensitivity analysis revealed that for the data considered the influence of nonuniform velocity distributions was minimal thus momentum correction factor, β was assumed equal to unity. The Blasius equation was used to estimate friction slope. WSPs estimated from the proposed equation were a closer match to measurements than the general equation for different channel bottom slopes and lateral inflow rates. The analogous results imply that the proposed equation is generic for any conditions of SVF with increasing discharge.