Optimal operation of pressurised irrigation distribution systems operating by gravity

On-demand pressurized irrigation distribution networks (IDN) operating by gravity may face pressure failures especially during the peak period. Several methods have been developed for irrigation sectoring where farmers are organized in turns. In general, the optimization methods used for pressurized systems consider, in the formulation of the problem, energy saving as objective function, which is not suitable for gravity-fed networks. In this study, an optimization model for pressurized IDN fed by gravity was developed to provide an optimal operating strategy based on irrigation periods. The model uses genetic algorithm to assign an irrigation period to each hydrant taking into account the minimization of pressure deficit at the most unfavorable hydrant of the network. The method is applied to a large scale irrigation distribution network in Italy. It shows to significantly improve the hydraulic performance of the network by insuring a satisfactory pressure at all hydrants, under the actual peak demand as well as higher water demands.