Optimization of pressurized irrigation network pipe diameters using genetic algorithm based on integer numeric (Case study: Ismail Abad network in Lorestan)

  Nowadays, human societies spend many costs to maximize profits and minimize their costs.The problem of selecting the best arrangement for the pipe diameters and the optimal pumping head of pressurized irrigating network so that minimize total cost to be produced and all restriction to be satisfy has received considerable attention by the engineers many years ago and is an important issue of hydraulic research. To date, many researches in the field of optimization of pressurized irrigation system to reduce the cost of this infrastructure are done. In this research often optimization of pressurized irrigation system have been conducted by using available commercial codes or toolbox's of conventional evolutionary algorithms that have been combined with a hydraulic models. In the present study, by Visual Basic programing language an optimization code based on genetic algorithm of integer numerical has been developed in which the optimal design of pressurized irrigation systems with branching layout is done by taking into account the velocity and pressure limits. In developed code that is based on a powerful optimization method e.g. genetic algorithm an integer numeric is assigned to each available diameter. Then, to determine the optimum diameter of pipes network, by applying the cross-over, mutation and reinsertion with elitism approach on set of chromosomes an integer numeric for each pipe is selected. The output of the model contains the optimal diameter and minimum cost of the irrigation network. Calibration and verification of the model was accomplished individually by comparing the model result with analytical solutions of several nonlinear problems included different constrains. At the end we have used of the proposed model for optimal design of Ismail Abad irrigation network in Lorestan province. The results showed that compared to existing conditions, optimized design by the present model reduces cost of implementation of pipelines of Ismail Abad irrigation network from 825935.28$ to 730958.37$. The present model has the ability to solve various optimizations linear and nonlinear problems included different constraints and the results of the model are completely equal to analytical solution results. In this research we try to investigate the application of the model on a large scale example so that the design of pressurized irrigation system of Ismail Abad in Lorestan province as a real example was done. The results were shown that the use of developed optimization model could reduce 11.5% the cost of implementation of Ismail Abad pipelines