Investigation of the Effect of Hydraulic Conditions on Optimization of Water Conveyance Channels with Different Sections

Channel design is one of the optimization issues aiming to minimize the cost of channel construction. In this definition, the amounts of sections variables, namely radius, slope side, bottom width and flow depth are calculated by minimizing cost of channels with regard to indicating the hydraulic flow constraint. In the current study, the optimal design problems are formulated in a nonlinear optimization framework with the objective function being a cost function per unit length of the channel has been expressed as the cost per unit length of the channel for lining, the depth-dependent unit volume earthwork cost and the cost of water lost. Using genetic algorithm, the parameters of four optimized channel sections including trapezoidal, rectangular, triangular and circular sections of channels were calculated. From the results obtained for restricting the flow equation in comparison with the total cost of construction of sections, circular section has less cost of construction. Using the proposed method, which has more precision and accuracy, several models with additional restriction of velocity, Froude number, and top width were considered for optimal design of the channel under special conditions. Restriction of velocity and Froude number caused increasing by %40 and %30 respectively, but restricted top width decrease about %48 of construction cost for trapezoidal, rectangular, and triangular sections. Restriction of Froude number, top width and velocity caused increasing, the cost construction of circular section.