Minimizing the Total Cost of Lining and Excavation Including Free Board

Lined canal with free board reduces the friction slopes, which enables the canal to be laid on a flatter bed slope. This increases the command area of canal, on other hand, as the lining permits higher average velocities, the canal can be laid on steeper slope to save the cost of earth work in formation. As the lining provide rigid boundary, it ensures protection against bed bank erosion. This paper presents design equation for minimizing the total cost of canal lining and excavation with free board. This can be overcome by using manning equation. It involve lining cost, cost of earth work which varies with the excavation depth, on account of complexities of analysis. The optimal cost equation along with the corresponding section shape coefficient is useful during the planning of canal project. A network of canal represent a major cost item in an irrigation project and economy of the canal network is vital. The maximum economy is achieved by minimizing the cost of lining of canal and excavation with free board. This technique is developed by taking illustration numerical example.