Optimal Design of Transmission Canal

This paper presents design equations for the least-cost canal sections considering earthwork cost which may vary with depth of excavation, cost of lining, and cost of water lost as seepage and evaporation from irrigation canals of triangular, rectangular, and trapezoidal shapes passing through a stratum underlain by a drainage layer at shallow depth. The optimal design equations are in explicit form and result into optimal dimensions of a canal in single-step computations. Using these least-cost section equations and applying the Fibonacci search method, equations for computation of the optimal subsection length and corresponding cost of a transmission canal have been presented. The optimal design equations along with the tabulated section shape coefficients provide a convenient method for the optimal design of a transmission canal. A step-by-step design procedure for rectangular and trapezoidal canal sections has been presented to demonstrate the simplicity of the method.