Energy efficiency of pressurised irrigation networks managed on-demand and under a rotation schedule

Collective irrigation networks are often sized to work on-demand. However, the high investment cost of this kind of infrastructure has lead to selection of scheduled rotational management, which reduces the investment cost. The objectives of this study were 1) to compare the operational costs of 4 irrigation networks using energy-based performance indicators, two managed to work on-demand and two under rotational management, and 2) to determine the most appropriate pumping station management using tools developed by the authors. The indicators used were calculated using data obtained in Spain during the 2007 and 2008 irrigation seasons. To obtain these indicators, hydraulic and energy simulation models were used. Results showed that the irrigation networks working under rotational management were more susceptible to inefficient use than on-demand irrigation networks. However, if the pumping stations in rotation scheduled irrigation networks were properly managed, greater energy efficiency can be obtained than in on-demand irrigation networks. Rotation schedule irrigation networks are more susceptible to inefficient management because of the lack of available management tools to select the configurations of open hydrants and choose the proper pumping head for each of these configurations. In the case studies examined, using the tools developed by the authors, improvements in energy efficiency achieved were between 3.5 and 24.9%, with higher potentials for improving energy efficiency occurring with irrigation networks managed to operate under a rotation schedule.

Research highlights
► It is important to evaluate and compare irrigation networks managed on-demand and under rotation schedule from hydraulic and energy points of view.
► Rotational scheduled networks are more susceptible of being improperly managed.
► If a proper management of the network is performed, better energy efficiency is obtained in rotation scheduled networks than in on-demand networks.
► A key point in rotation scheduled networks to optimise the sets of hydrants that are open in each sector