Peninsular Rivers, Lakes, Wetlands, and Soil Types in Spain

Factors Influencing the Peninsular Rivers

The characteristics of peninsular rivers are influenced by several factors, including:

• Climate: Rainfall and temperature patterns significantly impact river flow.
• Relief: The topography of the land affects the direction and speed of water flow.
• Lithology: The underlying rock type influences water absorption and erosion.
• Vegetation: Plant life can affect water flow and sediment levels.
• Human Action: Activities such as dam construction and irrigation alter river regimes.

River regimes can be classified as rain-fed, snow-fed, or a combination of both (mixed).

Basin Types

• Exorheic Basin: Characterized by water flowing into the open sea.
• Endorheic Basin: Refers to landlocked water bodies.
• Arheic Basin: Describes areas where water does not flow.

Features of Spanish Rivers

Spanish rivers exhibit several distinct features:

• Anthropic Regimes: Human activities significantly influence river behavior.
• Asymmetry of Aspects: A dominance of the Atlantic watershed is observed.
• Irregular Rivers: Due to irregular rainfall patterns, river flow is often inconsistent.
• Low-Average Flow: Factors such as rainfall, evaporation, and river surface area contribute to relatively low flow rates.
• Permeable Limestone Soils: The presence of limestone soils affects water absorption and drainage.

Lakes

Lakes are bodies of fresh or brackish water located in depressed areas. They reach a certain depth and can be stratified. There are approximately 2500 lakes in Spain.

Endogenous Lakes

These lakes are formed by forces originating within the Earth.

• Tectonic Lakes: Formed in areas of folds or faults.
• Volcanic Lakes: Occur when craters become flooded.

Exogenous Lakes

These lakes are formed by external forces.

• Glacial Lakes: Created by glacial activity.
• Karstic Lakes: Found in limestone areas.
• Aeolian Lakes: Formed in wind-eroded areas.
• Coastal Lakes: Located along coastlines.
• Endorheic Lakes: Formed where water is not strong enough to create a river.

Mixed Formation: Lake Banyoles is an example of a lake with both tectonic and endorheic origins.

Wetlands

Wetlands are tracts of land covered by shallow, inconstant water that may disappear during the summer. Examples include:

• Wetlands of La Mancha: Tablas de Daimiel, Lagunas de Toledo.
• Coastal Wetlands: Mar Menor, Ebro Delta.
• Riparian Wetlands: Galachos (approximately 2600).

Aquifers

Aquifers are accumulations of filtered groundwater that collect above an impermeable layer. They can discharge water into rivers or springs. Their exploitation is controlled by Hydrographic Confederations. There are over 400 aquifers. Dangers to aquifers include overexploitation, salinization, and pollution.

Soil

Soil formation is influenced by several factors:

• Bedrock: The underlying substrate from which soil is formed.
• Climate: Rainfall and temperature affect chemical and biological processes.
• Topography: Influences erosion and sedimentation patterns.
• Living Organisms: Plants and animals contribute to soil composition.
• Time: Soil formation takes centuries.

Siliceous Rock (Cantabrian)

• Moist Brown Earth: Acidic but arable soils.
• Rankers: Soils with limited evolution and thickness.
• Podzolic Soil: Soils with abundant humus.

Limestone Crag (Cantabrian)

• Limestone Brown Earth: Excellent for crops.
• Terra Fusca: Typically found in forests.

Mediterranean

• Southern Brown Earth: Acidic, low in humus, loose, and siliceous.
• Mediterranean Red Soil: Excellent for crops.
• Terra Rossa: Clay and limestone composition.
• Azonal Soil: Without a definite profile.
• Soils Between Zones: In the process of formation (alluvial, sandy, etc.).
• Antisols: Volcanic soils.
• Serosem Soil: Poor in humus, whitish, and lacking vegetation.