An overview of groundwater resources in Spain

In Spain, as in most arid and semiarid countries, during the last half century the silent revolution of intensive groundwater use has provided important socio-economic benefits. Nonetheless, traditionally water management has focused on surface water and has paid little attention to groundwater. The European Water Framework Directive (WFD) planning process has resulted in significant advancements in the knowledge of groundwater resources and their use in Spain. However, data on groundwater resources are still partially incomplete and an official countrywide overview of groundwater resources (and their uses) is still not available. At present the estimated groundwater demand is about 7,000 million m3/year, mainly for irrigation purposes. Intensive groundwater use has contributed to the degradation of this strategic resource, which is expected to be partially remediated by the WFD implementation. Previous studies in Andalusia found that in irrigated agriculture groundwater use was economically more productive than surface water. This was attributed to a series of factors, chiefly groundwater resilience to long dry spells, and it was suggested that this could apply also to other regions in Spain. The data presented in this chapter seem to question this former idea, since no clear correlation could be found between the source of water and its apparent water productivity in irrigated agriculture. This is an issue that merits further study, including combining local and country-wide data to refine the calculations