In the water framework directive, it comes in the definition of a hydrographic basin as the surface of land whose surface runoff flows in its entirety through a series of streams. These currents can be rivers and eventually lakes in the direction of the sea through a single mouth, estuary or delta. The hydrographic basin as a resource management unit is considered indivisible. Therefore, all hydrographic basins of Spain they have different characteristics.
In this article we are going to tell you all the characteristics and importance of the hydrographic basins of Spain.
Hydrographic basins of Spain
Each basin is divided in turn into other sub-basins. We define these sub-basins as the land surface whose surface runoff flows in its entirety through a series of streams, rivers, and eventually lakes. This water runoff is directed towards a point in a watercourse, which is generally a lake or a confluence of rivers. From this confluence of rivers a higher river is born in flow that goes towards the sea to the mouth. We are going to see which are the main hydrographic basins of Spain and their characteristics.
Duero hydrographic basin
It is the hydrographic basin that runs through the northwest of the peninsula and empties into Oporto. It has an area of about 97 km², of of which 81% correspond to the Spanish territory and 19% to the Portuguese territory. It is the basin with the largest area that spans the entire Iberian Peninsula.
Ebro River Basin
This is the river that runs through the northeast of the Iberian Peninsula. It begins in the Híjar mountain range and reaches its mouth in the Ebro Delta. Its surface area is approximately 85.000 square kilometers, making it the second largest in the entire Iberian Peninsula. Most of the rainfall that feeds the Ebro River comes from the Pyrenees in the northern part. To learn more about this important river, you can consult the article on the Ebro river and facts and curiosities about the rivers of Spain.
Tagus River Basin
It is the one that runs through the western part of the Iberian Peninsula and has its mouth in Lisbon. Its extension is 78 km², 467 which is distributed in 1% (66 km²) on Spanish soil and 34% on Portuguese lands. It is the third with the largest area in the entire Iberian Peninsula.
Guadiana hydrographic basin
It is the one that runs through the center and southwest of the Iberian Peninsula. Its mouth is located between Vila Real de Santo António and Ayamonte, making the border between Portugal and Spain. The number of main tributaries of this hydrographic basin is 137. This means that there are 137 rivers that feed all ecosystems with abundant water. Among the rivers that make up the Guadiana watershed are the following: the Guadlamez, the Bullaque, the Estena, the Zújar, the Zapatón, the Gevorra, the Murtigas stream and the Ardila stream, to name only the contributions of more than 90 Hm³. of natural form.
Hydrographic basin of the Guadalquivir river
It is the most important in the south of the peninsula. It is located entirely in Spain. Its extension is 57.527 km and extends through 12 provinces belonging to four autonomous communities, of which Andalusia represents more than 90% of the surface of the basin. The geographic space of the Guadalquivir demarcation is configured and delimited by various elements. On the one hand, we have the steep edges of Sierra Morena to the north. In the southern part we have the Betic mountain ranges and in the part close to the sea the Atlantic Ocean.
The climate of all this part is Mediterranean. Among the characteristics we have of Said climate we see that it is temperate and warm with temperatures of 16.8 degrees on an annual average. There is an irregularity in rainfall, with an average of 550 liters per square meter. The position of the territory in the part open towards the Atlantic is through which the oceanic storms of the western component penetrate. These storms are the cause of the distribution of the rains whose front advances in a southwest northeast direction. Once they have penetrated the Iberian Peninsula, they reach maximum values on the highest peaks that border and delimit the hydrographic basin of the Guadalquivir River. Of all the rains, they adopt a torrential character, which means that long periods of drought alternate with high temperatures that cause erosion.
When rains occur in a torrential manner, they occur sporadically but intensely. That is, when cIn rainfall it tends to do so intensely leaving a large amount of runoff water that ends up damaging ecosystems and crops. To learn more about the effects of drought in this basin, you can read the article on the effects of the drought in Spain and reservoir situation in summer.
Hydrographic basins of Spain: Júcar
This part includes all the basins that discharge into the Mediterranean Sea. We start from the margin of the left part of the Gola del Segura and at its mouth with the Cenia river. The total extension is 42.988,6 km² and extends through the provinces of Albacete, Alicante, Castellón, Cuenca, Valencia and Teruel, as well as a small area in the province of Tarragona.
Hydrographic basins of Spain: Segura river
The Segura river basin is the one that runs through the southeast of the Iberian Peninsula and has its mouth in the Mediterranean Sea. Its surface is approximately 18.870 km², affecting four autonomous communities, which are the Region of Murcia (practically in its entirety), the community of Andalusia (provinces of Jaén, Granada and Almería), Castilla-La Mancha (province of Albacete) and the Valencian Community (province of Alicante), being administered by the Segura Hydrographic Confederation, CHS.
Importance of the hydrographic basins of Spain
As we know, a country's water resources are based on the sum of its surface and groundwater volumes. River basins are responsible for storing as much surface water as possible. To this end, reservoirs are built with the primary purpose of collecting river water for storage. These waters are used for domestic purposes, agriculture, industry, etc. You can find out about the current status of the resources. reservoirs in Spain in 2024 and effects of drought in Spain.
I hope that with this information you can learn more about the hydrographic basins of Spain and their main characteristics.