Spain’s Water Resources: Aquifers, Droughts, and River Systems
Water Resources in Spain
Water Resources: Water policy is essential for natural ecosystems and human activities. Spain’s water comes from rivers, lakes, aquifers, and desalination. These resources are affected by physical factors like relief and lithology, and human factors like vegetation and land use.
Key Hydrological Terms
Drought: A prolonged period with little or no rain, common in Mediterranean climates characterized by warm summers.
Aquifer: An impermeable rock formation storing and allowing water passage. In Spain, 40% of the subsoil contains aquifers, providing a quarter of the country’s water. Overexploitation causes depletion and salinization, especially in the Mediterranean area.
Torrent: An intermittent watercourse flowing only after rainfall, typical in the Balearic Islands. Mallorca’s Torrent de Sant Miquel is notable, flowing into the S’Albufera lagoon.
Endorheism: Regions with drainage basins that do not flow to the sea, but into inland lakes or where water is lost through evaporation or infiltration. Examples include wetlands in La Mancha, like the Tablas de Daimiel National Park.
Exorheism: Regions with drainage basins flowing into the sea or ocean, such as most watersheds on the Iberian Peninsula.
Aquifer Salinization: Seawater intrusion due to decreased water levels in coastal aquifers, as seen in Campos, Mallorca.
Albufera: A coastal lagoon separated by a sandbar, rich in biodiversity. Notable examples include Valencia’s Albufera and Mallorca’s S’Albufera.
Aridity: Lack of soil moisture, defined as insufficient rain for vegetation, precipitation less than evaporation, or rain failure making agriculture impossible without irrigation.
Desertification: Loss of vegetation due to natural or human causes, including dry weather, irregular rainfall, deforestation, and overexploitation of land and aquifers. A significant issue in areas like Granada, AlmerÃa, Murcia, Valencia, Alicante, and the Ebro Valley.
Low Water Level: A significant drop in sea or river level, common in Mediterranean rivers like the Segura and Turia during summer, with occasional rapid increases during autumn due to cold drops.
Flash Flood (Revinguda): A sudden, significant increase in river or stream water level, causing flooding, especially in the Mediterranean area during autumn rains.
Slope Basin: A river basin draining into a single sea. The Iberian Peninsula has three aspects: Mediterranean, Atlantic, and Cantabrian.
River Regime: The annual water flow pattern of a river basin. Most Spanish rivers have irregular regimes, except in the north, with floods during thaw and rains, and low flows during dry periods.
Inter-basin Water Transfer: Transferring water between surplus and deficit basins. Spain operates 38 transfers, notably the controversial Tajo-Segura. The 2001 National Water Plan proposed a major Ebro transfer, later repealed.