The paradox of irrigation scheme modernization: more efficient water use linked to higher energy demand

In recent years, many modernization processes have been undertaken in irrigation districts with the main objective to improve water use efficiency. In southern Spain, many irrigation districts have either been modernized or are currently being improved. However, as part of the modernization process some unexpected side effects have been observed. This paper analyzes the relative advantages and limitations of modernization based on field data collected in a typical Andalusian irrigation district. Although the amount of water diverted for irrigation to farms has been considerably reduced, consumptive use has increased, mainly due to a change in crop rotations. The costs for operation and system maintenance have dramatically risen (400%) as the energy for pumping pressurized systems is much higher now compared to gravity fed systems used previously. Then a regional analysis in ten Southern Spain irrigation districts of the relationship between energy requirements and irrigation water applied has been carried out. Results show that to apply an average depth of 2590 m(3) ha, the energy required was estimated to be 1000 kWh ha(-1). A new approach is needed that involves efficient management of both water and energy resources in these modernized systems. Finally, some energy saving options are identified and discussed.