Although the climate varies within Spain's borders, the country as a whole is one of the driest in Europe. By the 1920s, Madrid sought to strategically use its somewhat limited water resources by building infrastructure for electricity production and to support agriculture. After continued development throughout the 20th century, Spain boasts roughly 1,300 dams — the world's highest number of reservoirs per million inhabitants.
In drought years, access to irrigation can provide a buffer for agricultural production. Climate experts indicate that this safety net will become more necessary over the coming decades if predictions of a hotter, drier Spain prove correct. The nation's average water exploitation index, a measure of water resources used compared with long-term renewable resources, indicates moderate levels of stress. (A measure of 20 percent indicates stress, while 40 percent is severe stress that is clearly unsustainable; Spain's index is 34 percent.) However, the regions of Andalusia and Segura have water exploitation indices of 164 percent and 127 percent respectively, meaning that these regions abstract more water each year than is replenished. Declining groundwater in southern Spain's Guadiana Basin has dried out peat land, and over-abstraction in some coastal aquifers has resulted in saltwater intrusion, decreasing the quality of aquifer water. Under these conditions, continued and increased reliance on irrigation, in addition to industrial and urban demands, will only increase the stress on these resources, especially in areas where stress and overuse already exist.
Although climate change and financial and social limits to simple coping mechanisms make it likely that Spain will continue suffering water stress and localized scarcity, there is a bright side. Spain is not the only country trying to do more with less water. Virtually every country will be touched in some way by water stress or scarcity in the coming decades. Conservation and infrastructure improvement remain vital strategies, but alternative water sources, especially for urban consumption, will become increasingly necessary. Desalination is poised to play a large role in supplementing the world's natural fresh water supply, and Spain is home to many of the world's leaders of this technology.
Spain is the largest user of desalination in the Western world, possessing roughly 700 plants that produce enough water each day for 8 million people. More important, Spanish companies make up the largest percentage of competitors in the global market, covering the life cycle of the technology from research, to design and engineering, to construction and operation. More than 50 companies are members of the Spanish Desalination and Reutilization Association. As global demand rises, from the Middle East to California, Spain's desalination companies are poised to benefit, both in Spain and abroad.