| Ebro | |
| Catalan: Ebre | |
| River | |
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The Ebro River in Zaragoza
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| Country | Spain |
|---|---|
| Tributaries | |
| - left | Oca, Oja, Tirón, Najerilla, Iregua, Cidacos, Alhama, Jalón, Huerva, Martín, Guadalope, Matarranya |
| - right | Nela, Jerea, Bayas, Zadorra, Ega, Arga. Aragón, Gállego, Segre |
| Source | |
| - location | Pico Tres Mares, Cantabria, Spain |
| - elevation | 1,980 m (6,496 ft) |
| - coordinates | |
| Mouth | |
| - location | Mediterranean Sea, Tarragona, Spain |
| - elevation | 0 m (0 ft) |
| - coordinates | |
| Length | 910 km (565 mi) |
| Basin | 80,093 km2 (30,924 sq mi) |
| Discharge | mouth |
| - average | 426 m3/s (15,044 cu ft/s) |
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Watershed of the Ebro
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The Ebro (Spanish: [ˈeβɾo]) or Ebre (Catalan: [ˈeβɾə] or [ˈeβɾe]) is one of the most important rivers in the Iberian Peninsula. It is the biggest river by discharge volume in Spain.
The Ebro flows through the following cities:
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Its source is in Fontibre (Cantabria), from the Latin words Fontes Iberis, source of the Ebro. The upper Ebro rushes through rocky gorges in Burgos Province. Flowing roughly eastwards it begins forming a wider river valley when it reaches Navarre and La Rioja thanks to many tributaries flowing down from the Iberian System on one side, and the Navarre mountains and the western Pyrenees, on the other.
The valley expands and the Ebro's flow then becomes slower as its water volume increases flowing across Aragon. There, massive tributaries flowing from the Central Pyrenees and the Iberian System discharge large amounts of water, especially in spring during the thawing season of the mountain snow. As it flows through Zaragoza the Ebro, emblematic river of Aragon, is already a sizeable river. The Basilica of Our Lady of the Pillar stands next to the Ebro.
After reaching Catalonia the Ebro Valley narrows and the river becomes constrained by mountain ranges, making wide bends. Massive dams have been built in this area, like the dams at Mequinensa, Riba-roja, Flix. In the final section of its course it bends southwards and flows through spectacular gorges. The massive calcareous cliffs of the Serra de Cardó range constrain the river during this last stretch, separating the Ebro Valley from the Mediterranean coastal area. After passing the gorges, the Ebro bends again eastwards near Tortosa before discharging in a delta on the Mediterranean close to Amposta in the province of Tarragona.
The Ebro Delta (in Catalan: Delta de l'Ebre), in the Province of Tarragona, Catalonia, is one of the largest wetland areas (320 km²) in the western Mediterranean region. The Ebro delta has expanded rapidly on soils washed downriver—the historical rate of growth of the delta is demonstrated by the town of Amposta. A seaport in the 4th century, it is now located well inland from the current Ebro river mouth. The rounded form of the delta attests to the balance between sediment deposition by the Ebro and removal of this material by wave erosion.
The modern delta is in intensive agricultural use for rice, fruit (in particular citrus), and vegetables. The Ebro delta also has numerous beaches, marshes, and salt pans that provide habitat for over 300 species of birds. In 1983 Spain designated a large part of the delta as Ebro Delta Natural Park (Parc Natural del Delta de l'Ebre) to protect the natural resources.[1] A network of canals and irrigation ditches constructed by both agricultural and conservation groups are helping to maintain the ecologic and economic resources of the Ebro Delta.
The Romans named this river Iber (Iberus Flumen), hence its current name. Arguably the whole peninsula and some of the peoples living there were named after the river.[2]
In antiquity, the Ebro was used as the dividing line between Roman (north) and Carthaginian (south) expansions after the First Punic War (264-241 BC). When Rome, fearful of Hannibal's growing influence in the Iberian Peninsula, made the city of Saguntum (considerably south of the Ebro) a protectorate of Rome, Hannibal viewed the treaty as an aggressive action by Rome and used the event as the catalyst to the Second Punic War.
One of the earliest Cistercian monasteries in Spain, Real Monasterio de Nuestra Señora de Rueda (Royal Monastery of Our Lady of the Wheel), is located on the banks of the Ebro in Aragon. Established in AD 1202, the edifice survives intact. The monastery is strongly connected to the Ebro, since it used one of the first large waterwheels built for the production of power in Spain. The monastery also diverted flow from the Ebro to create a circulating, hydrological central heating system for its buildings.
The river Ebro in 1938 was the starting ground of one of the most famous Republican offensives of the Spanish Civil War. Known as the Battle of the Ebro, the offensive ended in defeat for the Republican forces, although they enjoyed success in its first stages. They were not able to reach their objective of Gandesa.
The Ebro is the most important river in Spain, 928 km in length and with a drainage basin of 85,550 km². However, the mean annual flow decreased by approximately 29% during the 20th century due to many causes: the construction of dams, the increasing demands for irrigation and the evaporation (higher than the rainfall, due to low rainfall, high sunshine and strong and dry winds) from reservoirs in the river basins. This situation has a direct impact on the deltaic system at the mouth of the river because its hydrological dynamics are mainly controlled by the river discharge.
The decrease in river discharge has meant introduction of the salt wedge further into the river. The mean annual river flow is approximately the critical flow which determines the formation and the break-up of the salt wedge. Thus, when the river discharge is between 300 and 400 m³, the salt wedge can occupy the last 5 km of the estuary, but when the discharge is between 100 and 300 m³, the salt wedge can advance up to 18 km from the mouth. For less than 100 m³, the salt wedge quickly advances to its maximum extent, reaching 32 km from the mouth. In addition to decreased mean annual flow, the increased river regulation in the Ebro basin has produced daily and seasonal changes in the flow pattern.
With regards to the sediment load, several authors conclude that the sediment load was reduced by more than 99% during the last century. The drastic reduction in sediment transport implies a sediment deficit in the Delta, which is causing the erosion of the coastline. This erosion, together with the sinking of the Delta produced by soil compaction and tectonic subsidence, cannot be balanced by the deposition of fluvial sediments, nearly all of which are retained behind the dams.
River flow in Zaragoza from the end of the nineteenth century:
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The Ebro poured 1,874 hm³ in the river delta from 2007-03-27 to 04-11, with an average of 117 hm³/day .
The Ebro Delta Natural Park, with a total surface area of 7,802 ha, was established in 1986 and is of international importance for 8 of its plant species and 69 of its vertebrate fauna. It has some 95 breeding species of birds, is also very important for a wide range of overwintering species, and serves as an essential stopover point for large numbers of migratory birds. The Ebro delta has the world's largest colony of Audouin's Gulls. In 2006 it held a record number of more than 15,000 pairs.
There are concerns about the ecological impact of introduction of foreign species that is almost always a burden, affecting much of the original ecosystem introduced species rapidly caused the extinction of numerous indigenous species. The introduction of American crayfish Procambarus clarkii has resulted in economic losses, introduced elsewhere for cultivation, its success is attributable to its ability to colonise disturbed habitats that would be unsuitable for the edible iberian crayfish. The semiacuatic rodent Myocastor coypus or nutria is presuming to expand in some northwest tributaries of the head damaging crops and protected national parks in Basque Country.
The zebra mussel, an invasive species, is expanding upstream in Ebro waters. Due to its rapid rate of reproduction, the species adversely affects the port underwater machinery as well as that of dams and hydroelectric plants, in addition to competing with native species. Following the introduction of Wels catfish are fishes whose number is in clear and rapid decline. Since its introduction in the reservoir Mequinenza in 1974 - has spread to other parts of the Ebro basin over Ebro and its tributaries, especially river Segre. Some endemics species of iberian barbels, genus Barbus in the Cyprinidae, having once been abundant especially in the Ebro river. Competition and predation by Wels catfish has caused its complete disappearance in the middle channel Ebro around 1990. The ecology of the river also, has now a major development in the amount of aquatic vegetation, seaweed and algae. Barbel species from mountain stream tributary of the Ebro that Wels catfish has not colonized, were not affected.