Kiyumars Roushangar - Associate Professor, Department of water engineering, Faculty of Civil Engineering, University of Tabriz,
Aida Nouri - Ph.D. Candidate, Department of water engineering, Faculty of Civil Engineering, University of Tabriz,
Hassan sani - M.Sc, Department of Civil Engineering, University of Tabriz, Tabriz, Iran,

Manufactured open channels are costly in the basic terms of the construction material. Optimum design of the channel structures includes reducing the total amount of costs of channel’s length unit. The present research aimed to optimize the design of Trapezoidal Channel Cross Section. In the optimization process, the objective function referred to the costs of lining length unit, the cost of unit volume earthwork, and the cost of water loss through seepage and evaporation. At first, a general resistance equation has been applied as an equality restriction. Next, Genetic Algorithm (GA) was used for optimal design of trapezoidal channel section with depth, bottom width and side slope variables. Two models have been proposed and evaluated including no restriction, restricted Froude number. The numerical outcome were obtained by the GA and compared with classic results to determine the most efficient model. The results indicated that the restricting Froude number increased the total cost

Open channels; Optimization; Froude numbers; trapezoidal section