Cost and flooding probability minimization based design of HBPS (horizontal bottom and parabolic sides) channel

This study proposes to use the channels having horizontal bottom and parabolic sides (HBPS) as substitute for trapezoidal channels. The acceptability of HBPS channel is contested by using the criteria of minimization of cost and flooding probability. An optimization model is developed to minimize the total cost of construction and flooding probability. The bi-objective model is solved by using the constraint method of multiple objective optimization technique. The objective of minimizing the flooding probability is converted to the flooding probability constraint. The first order analysis is used to develop the flooding probability constraint equation. The optimization model is solved by using projected augmented Lagrangian method. The optimization model is applied for design of HBPS and trapezoidal cross sections considering the composite and uniform roughness cases. The application results show that the objectives of minimizing the flooding probability and the total costs conflict each other when the desired flooding probability values are less than the value that occur at the traditional minimum cost design of the channels. The new HBPS cross section is found to remain cheaper than the traditional trapezoidal cross section. The developed optimization model has a potential for practical use.