Single universal dimensionless specific energy curves for trapezoidal and circular shaped open channels

Trapezoidal and circular channels are commonly employed as conveyances of open channel flow in irrigation canals, for storm and wastewater drainage and at times for transporting raw water. Open channel flow problems in such cross sections typically involve determination of alternate depths, critical depths and specific energy that require solving equations for which explicit solutions are difficult to obtain. This paper demonstrates the development of a solution for such problems through the use of single universal dimensionless specific energy-depth curves for each of the trapezoidal and circular shaped channels. The dimensionless curves are demonstrated to be simple to develop and use and can be adapted for wide range of user environments. Simulation of the graphical solution over broader range of flows and dimensionless depths of flow shows that the solution is reasonably accurate with percentage error of estimation of depth varying between 0 and 4 % with mean percentage error of 1.1 % for trapezoidal shaped channels and 1.2 % for circular shaped channels. Further application examples have been provided that show that the proposed graphical procedure can achieve results that are within close range of the precision of results obtained using numerical methods.