Can Irrigation Technologies Save Water in Closed Basins? The effects of Drip Irrigation on Water Resources in the Guadalquivir River Basin (Spain)

Numerous institutions and governments have opted to increase irrigation efficiency to tackle water problems, especially water scarcity. The purpose of this research is to analyse the effects that the introduction of new irrigation technologies has in closed basins with high water reuse and where most of the water is used for agriculture. We analyse the evolution in the water supply, the irrigated area and the crops in three irrigation communities in different sections of the Guadalquivir River Basin. The results are compared with irrigation areas where traditional irrigation systems are still in use as control groups. The new irrigation systems have triggered a wide range of responses in the irrigated areas, including increases in the size of the irrigated areas, the introduction of crops with greater water requirements, and the production of two harvests per year. Such intensification features have been enabled by the exploitation of resources that previously returned to the system. The analysis of the water balances shows that appropriate measures need to be implemented to reduce rather than increase pressure on resources, most prominently including a revision of water rights and devoting the savings to improving the quality of water ecosystems and/or to urban supply.