Groundwater mining: benefits, problems and consequences in Spain

Abstract

In many arid and semiarid areas, as is the case of south-eastern Spain and the Canary Islands, water is scarce but highly demanded for irrigation of cash crop and for supply to urban and tourist areas. Generally, water quantity dominates over water quality issues. Surface water resources are scarce. So, in south-eastern Spain, out of the area of influence of the permanent Segura River, and in the Canary Islands, groundwater is often the main or the only reliable natural water resource. As a consequence, aquifers are often intensively exploited and some of them subjected to continuous depletion of their reserves (groundwater mining). In south-eastern Spain, the cumulative groundwater reserve depletion is about 15 km3. In Gran Canaria and Tenerife Islands it is about 2 km3. The current rate of depletion is 0.3 to 0.4 km3/year. Although obtaining groundwater is expensive, in most cases it is still cheaper than desalinated and/or reclaimed waste water made available at the place of use when full costs are considered. Environmental damage is not evaluated. Groundwater intensive use and mining have been and still are the drivers of economic and social development. According to European and Spanish legal regulations, the current situation is not acceptable. To address problems, good governance and a change in the water use paradigm are needed. Solutions depend largely on controlling water use and on demand management. As this is administratively difficult and politically unpalatable, most action is currently directed to increase the public offer of water through import from outside—if it is possible—seawater desalination and wastewater reuse, but at subsidized prices (tariffs). This is economically, politically and environmentally questionable, and an economic distortion which delays the change, deters private investment in groundwater, and needs continuous public funding. In the case of the Canary Islands, this also disturbs groundwater markets. What is presented also happens in other world areas. It is not new and does not involve research but summarizes a long and documented experience and solution attempts that are of relevance to evaluate and address problems elsewhere.