A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 2004

The aim of this study is to develop a genetic based programme for pipe diameter optimization. The developed programme is applied to a case study, distribution system of Weligama water supply scheme in Sri Lanka. Then the performance of genetic algorithm is compared for cross validation with that of non linear programming. It is proven that the genetic algorithm method using the standard three operators is particularly effective in finding global optimal solution for the case study network. It should be noted that the genetic algorithm technique is ideally suited to discrete problems such as selection of commercially availably pipe sizes. Furthermore, water demand for the design is estimated and those demand data are input to the GA program. The output diameter values from the GA program are compared with the pipe diameters of existing distribution system. It is found that some of the existing pipe diameters will not be able to cater for the demand at year 2011. And at the same time, it is evident that 148 number of pipes in the existing distribution system have been over-estimated. The National Water Supply and Drainage Board in Sri Lanka designs pipe networks mainly not to violate the hydraulic constraints. Manual calculations followed by hydraulic simulations are carried out to find the suitable pipe network design. In this study, attempts have been made to obtain a pipe network, which satisfies hydraulics and the cost optimality.