Water and Biogeographic Diversity in Spain

Posted on Nov 26, 2024 in Geology

Unit 3: Water and Biogeographic Diversity in Spain

1. Water Diversity

The wide variety of weather and climate in Spain results from the effects of various geographical and thermodynamic factors.

1.1. Influencing Factors

Physical Factors – Climate:

The water of rivers, lakes, and aquifers comes from rainfall, creating a contrast between wet and dry Spain.

  • Relief and Topography: Influence the organization of watersheds, erosive capacity, and the formation of lakes and aquifers.
  • Soils: Rock type favors runoff (clays) or facilitates water infiltration (limestone).
  • Vegetation: Acts as a shield against radiation and reduces evaporation.
Human Factors:
  • Drinking water supply and irrigation.
  • Construction of hydraulic works (dams and transfers).

1.2. Factors Influencing Peninsular Rivers

  • Rainfall: Determines the absolute flow regime of rivers.
  • Full Flow: The amount of water passing in one second by one point.
  • Fluvial Regime: Relates to seasonal flow variations. These variations depend on rainfall distribution and the importance of snowmelt.
River Types:
  • Nival: Characteristic of rivers originating in the mountains. Maximum flows occur in late spring or early summer due to melting. Low waters occur in winter.
  • Pluvial: Depends on rainfall and therefore the rainfall characteristics of each climate zone.
  • Mixed or Complex: Nivo-pluvial (snowmelt predominant) or pluvio-nival (rainfall predominant).
  • Relief and Topography: Determines the organization of river basins and watersheds, slope, and soil erosion.
  • Catchment: The area whose waters flow into a major river and its tributaries. Basins are separated by watersheds, which coincide with a change of slope. E.g., Los Montes de Toledo are the watershed between the Tagus and Guadiana basins.
  • Slope: The set of basins whose waters flow into the same sea. The most important feature is the large asymmetry between the Atlantic and Mediterranean slopes, due to the tilting of the plateau to the west.

1.3. Peninsular Hydrographic Areas

A. Cantabrian Rivers:
  • Short rivers originating in mountains near the coast.
  • Great erosive capacity.
  • Numerous and generally plentiful.
  • Suitable area for hydroelectric power.
B. Atlantic Rivers:
  • Long rivers born near the Mediterranean and flowing into the Atlantic.
  • Mostly flow through plains.
  • Irregular low flow regime in summer, especially in central and southern areas.
C. Mediterranean Rivers:
  • Short rivers (except the Ebro), born in mountains near deforested hillsides.
  • Irregular regime with significant droughts in summer and autumn and catastrophic floods (cold drop).
  • Notable streams and intermittent courses caused by rain, often dry for much of the year.

In the Canary Islands, due to aquifer depletion, water treatment plants have been installed.

2. Spanish Lakes and Wetlands

2.1. Lakes

Spanish lakes are small-scale and often seasonal, silting up due to river contributions and human practices (irrigation, well construction, and drying).

Lake Types:
  • Endogenous Lakes: Caused by internal Earth forces or phenomena.
    • Tectonic Lakes: Formed on sunken land. E.g., La Janda lagoon, Cádiz.
    • Crater Lakes: Lakes remaining in ancient volcano craters. E.g., Campos de Calatrava (Ciudad Real).
  • Exogenous Lakes: Caused by external forces (water and ice erosion).
    • Glacial Lakes: Formed from the excavation of cells by ice, located in the Pyrenees (mountain lakes). E.g., Aigüestortes National Park and Lake Sant Maurici. Also found on the plateau, e.g., Sanabria lakes in Zamora.
    • Karst Lakes: Created by the dissolution of limestone or plaster. E.g., Ruidera Natural Park (Ciudad Real).
    • Arreicos Lakes: Widespread exogenous lakes characteristic of arid or semiarid plains of sedimentary basins and depressions. E.g., Tablas de Daimiel National Park (Ciudad Real).
    • Dune Lakes: Excavated by the wind. E.g., Empordà district, Girona.
    • Coastal Lagoons: Salt lakes separated from the sea by a barrier island. Predominant in the lower Guadalquivir, Mar Menor, and the Mediterranean mouths of some rivers like the Ebro.

2.2. Wetlands

Tracts of land covered by shallow, often intermittent water, including ponds, marshes, deltas, and lagoons. Areas of great biological wealth and biodiversity, particularly in plant and animal species living between water and earth. They constitute one of the largest water reserves in Europe. E.g., Tablas de Daimiel, Villacañas gaps (Toledo), Ebro Delta, Guadalquivir marshes (Doñana National Park in Seville and Huelva), Valencia lagoon, and Mar Menor.

3. Aquifers

Bags of groundwater formed when rainwater infiltrates and accumulates over an impermeable stratum. Benefits include lack of harmful organisms and stable temperature and composition. Used in irrigation. Issues include overexploitation and pollution. Over 400 aquifers in the Iberian Peninsula, mainly in Tertiary depressions near rivers and headwaters. E.g., Aquifer 23 or Manchego Aquifer.

4. Vegetation

The set of plant species located in a territory. Four vegetation zones in the Iberian Peninsula:

  • Boreoalpine Region: Elevated areas of the Pyrenees and Cantabrian Mountains.
  • Eurosiberian Region: North of the peninsula and parts of the Central System and Iberian System.
  • Mediterranean Region: Most of the peninsula.
  • Macaronesian Region: Canary Islands.