Economic productivity of irrigation water and the closure of a river basin in Southern Spain

Abstract

The expansion of irrigated areas in river basins where water resource is scarce usually leads to the closure of the river basin (RB), as a final result of a multiple pressure-response process. This has been the trajectory followed by the Guadalquivir RB, which is the main river in southern Spain. As response to these pressures, farmers have tended to use the resource more efficiently through a modernisation of their irrigation methods and the widespread of deficit irrigation and high-precision techniques. These individual decisions have sought to maximise the economic return to the limited resource (water), provoking changes in crops composition in order to maximize the productivity of irrigated agriculture and the mean productivity per irrigation unit. The analysis carried out in this paper shows a significant increase in irrigation water mean productivity in the period (1989-2005), driven by the creation of new irrigated areas devoted to high value crops and with a dominant use of deficit irrigation strategies, while a second phase (2005-2012) is defined by slower growth in terms of the mean productivity of irrigation water, primarily as a result of a significant reduction in water use per area. Findings show the patterns followed by irrigation water productivity in the analysed case study, which seems to have reached its full capacity.