Lesson 3 The Hydrography of Spain
Hydrography is the geographical study of the water of the Earth. Rivers are natural, flowing bodies of water that start in mountainous regions, cross the landscapes and flow into the sea, lakes or other rivers (tributaries = afluentes).
The elements of a river are: The source (where the water emerges to become a river), the mouth (where the river ends) and the channel or course (where the water flows). There are three parts in a river:
- Upper course: In mountainous areas, heavy erosion.
- Middle course: In the central section, form tributaries and valleys, heavy erosion and sedimentation.
- Lower course: the mouth of the river, forms deltas.
Rivers have some characteristics and depend on the relief and climate:
- Length: The distance.
- Discharge: The amount of water passing through the river.
- Regime: The discharge variation throughout the year
In Spain there are three basins:
- The Cantabrian Basin: short rivers, come from the Cantabrian Range. Strong current all the year. Good place to build reservoirs. The main rivers are: Eo, Navía Nalón, Besaya Nervión y Bidasoa.
- The Atlantic Basin: Rivers run through the Meseta and the Guadalquivir Depression (long and voluminous rivers with variable regime). The main rivers are Tambre, Miño, Sil, Duero, Tajo, Guadiana, Genil and Guadalquivir.
- The Mediterranean Basin: Shorts except the Ebro, variable regimes, in some cases disappear in summer. The main rivers of the east are: Ter, Llobregat, Ebro, Turia, Segura, Jucar and Guadalhorce.
The particular landscape and climate in the Balearic and Canary Islans prevent the formation of permanent rivers. When it rains torrents are formed in Balearic Islands and ravines (cascadas - cataratas) in the Canary Islands.
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