Optimal Design of Irrigation Networks Using the Dynamic Method and a Simplified Nonlinear Method

The designating factors in the design of branched irrigation networks are the cost of pipes and the cost of pumping. They both depend directly on the hydraulic head of the pump station. It is mandatory for this reason to calculate the optimal head of the pump station as well as the corresponded optimal pipe diameters, in order to derive the minimal total cost of the irrigation network. The mathematical research of the problem, using the classical optimization techniques, which have been proposed until now, is very complex and the numerical solution calls for a lot of calculations, especially in the case of a network with many branches. For this reason, many researchers have developed simplified calculation methods with satisfactory results and with less calculation time needed. In this paper a comparative calculation of the pump station optimal head as well as the corresponded economic pipe diameters, using the dynamic programming method and a proposed simplified nonlinear programming method, is presented. Comparative evaluation in a particular irrigation network is also developed. Key-Words: Irrigation, head, pump station, network, cost, optimization, simplified method, dynamic.