Document Type : Research Article
Industrialization of the human life requires that more attention is paid to the environmental issues. Sewers are one of the main sources of pollution and must carefully be collected and disposed. The cost of construction and maintenance of the sewer systems is very high in particular the large scale systems required for populated cities. Any reduction in the design cost of these structures lead to a considerable savings. Many researchers have studied the use of optimization algorithms for the optimal design of sewer networks. In this paper the capabilities of mathematical programming and genetic algorithm for the optimal design of sewer networks are investigated and compared for networks with fixed layout. Two different models, namely modified Hazen-Williams and Manning formula with fixed and variable friction coefficient is used for hydraulic simulation of the network. Nodal elevations of the network are considered as the decision variables of the problem leading to the possibility of discrete determination of the pipe diameter. Successful application of these algorithms demonstrates the ability of proposed models to optimal design of sewer networks.