The Guadiana drainage basin in the Iberian peninsula
Ptolemy'sGeography recorded theCeltiberian name asAnas, meaning a marshy area orbayou. The Romans adapted this name asFlumenAnās, which wasetymolygised as the "River of Ducks." After theMuslim conquest of the Iberian Peninsula, the name was extended and referred to asWadi Ana, later passed on to Portuguese and Spanish settlers as theOuadiana, and later justOdiana. Since the 16th century, the name slowly evolved to take on the formGuadiana, a cognitive variation that developed from many Andalusi river place-names beginning inwadi using the prefixguad- such as the hydronymsGuadalquivir,Guadalete, andGuadarrama.
Lake Alqueva along the River GuadianaTheAlqueva Dam, located in the southern arm of the Guadiana, is responsible for Western Europe's largest reservoir.
The Guadiana flows east to west through Spain and south through Portugal, then forms the Spanish-Portuguese border; it flows into theGulf of Cádiz, part of the Atlantic Ocean, betweenVila Real de Santo António (Portugal) andAyamonte (Spain). It is 818 kilometres (508 mi) long, of which 578 kilometres (359 mi) are within Spanish territory, 140 kilometres (87 mi) within Portugal, while 100 kilometres (62 mi) are shared between the two nations. About 82 percent, 55,444 square kilometres (21,407 sq mi), of its basin is in Spain, while about 17 percent, 11,560 square kilometres (4,460 sq mi) is in Portugal.[3]
The exact source of the river in Castilla-La Mancha is disputed, but it is generally believed to spring in theOjos del Guadiana [es],Villarrubia de los Ojos municipal term,Ciudad Real Province, Castile–La Mancha, about 608 metres (1,995 ft) in elevation.
A classic theory introduced byPliny the Elder, was that the river originated from theLagunas de Ruidera and divided into two branches: the Upper Guadiana (Spanish:Guadiana Viejo) and the Guadiana, while separated by a subterranean course. This legend developed from a misguided belief (which persisted until the 19th century) that the river appeared and disappeared over time, because of its subterranean tributary. In fact, no subterranean course exists, and the belief that the Lagunas de Ruidera is the source is also controversial. toponymically and traditionally the Upper Guadiana,[4] which runs fromViveros (Albacete) untilArgamasilla de Alba (Ciudad Real) had been identified as the main branch of the Guadiana. But even hydro-geological characteristics indicate that the Upper Guadiana may not be the principal river within the system.[5]
Another of the origin theories, postulated that theCigüela andZáncara rivers were the sources of the Guadiana. Today, they are considered integral parts of the river's headwaters and important tributaries, but not necessarily the exact origin. The Ciguela's source is in Altos de Cabreras (Cuenca) and pertains to theSistema Ibérico, at an elevation of 1,080 metres (3,540 ft). Its course is 225 kilometres (140 mi) long, receiving contributions from the rivers Jualón, Torrejón, Riánsares, Amarguillo andZáncara. The union of the rivers Ciguela and Záncara permits the replenishment of the waters in theTablas de Daimiel National Park, a wetland that was designated for protection by the Spanish government in 1973 (situated in the municipalities of Villarrubia de los Ojos andDaimiel, in the province of Ciudad Real).
From its origin/spring runs from the southern Iberian plain in a direction east to west, to near the town ofBadajoz, where it begins to track south leading to the Gulf of Cádiz. The Guadiana marks the border of Spain and Portugal twice as it runs to the ocean: first, between the RiverCaia andRibeira de Cuncos, then later from theRiver Chança until its mouth. The river is not used to completely mark the boundary between the two states; between the Olivenza ravine and the Táliga ravine, the border still remains a disputed section claimedde jure by both countries and administeredde facto by Spain (as part of the Spanishautonomous community ofExtremadura).
For the most part, the Guadiana is navigable from the Atlantic Ocean untilMértola, a distance of 68 kilometres (42 mi). North of Mértola on the Guadiana is the highest waterfall is Southern Portugal calledPulo do Lobo.
The ecosystem has Mediterranean hydrological characteristics, including high variation in intra- and inter-annual discharge, large floods and severe droughts. This variability is a consequence of considerable variation in rainwater supply averaging around an annual mean of 400 to 600 millimetres (16 to 24 in).[6] The climate issemiarid with an average annual temperature of 14 to 16 °C (57 to 61 °F).[7]
The river empties into the Gulf of Cádiz between Ayamonte and Vila Real de Santo António, the two highly touristic regions of theAlgarve and the sea-side ofAndalusia. There it forms asaltmarshestuary. The estuary has a maximum width of 550 metres (1,800 ft), and its depth ranges from 5 to 17 metres (16 to 56 ft).Tides are semi-diurnal, ranging from 0.8 to 3.5 metres (2.6 to 11.5 ft); their upriver propagation is limited by falls situated 76 kilometres (47 mi) from the mouth at Moinho dos Canais. In the lower estuary there are nature reserves covering a total of 2,089 hectares (5,160 acres); in Spain, the Marismas deIsla Cristina and, in Portugal, theReserva Natural do Sapal de Castro Marim e Vila Real de Santo António (English:Castro Marim and Vila Real de Santo António Marsh Natural Reserve); they give a valued nature conservation character to the region.
In Spain, three autonomous communities, (Castilla-La Mancha, Extremadura and Andalusia) (comprising the provinces ofCiudad Real,Badajoz, andHuelva) are crossed by the Guadiana. Meanwhile, in Portugal the river crosses the regions ofAlentejo andAlgarve, and the districts ofPortalegre,Évora,Beja andFaro.[citation needed]
There are over 30 dams on the river basin. The following are the dams on the Guadiana river itself:[8]
Alqueva Dam, the largest dam, located nearMoura, in theBeja District, responsible for the largest reservoir in Western Europe. (There are several larger ones inRussia andUkraine.) The Alqueva reservoir, occupies an area of 250 square kilometres (97 sq mi), with a capacity for 4,150cubic hectometres (3,360,000 acre⋅ft).[citation needed]
Díaz-Pintado Carretón, José (1997). D.L. Soubriet (ed.).El polémico Guadiana: historia y leyenda del río Guadiana Alto [The Guadiana Controversy: History and Legend of the Upper Guadiana River]. Ciudad Real, Spain: Argamasilla de Alba.ISBN84-922069-9-3.
Alonso, A. Cabo (1990)."Guadiana". Madrid, Spain: Railp. Archived fromthe original on 16 July 2011. Retrieved2 July 2010.
Aldaya, Maite M.; Llamas, M. Ramón (2008). "Water Footprint Analysis for the Guadiana River Basin".Papeles de água Virtual(PDF). Vol. 3. Madrid, Spain: Fundación Marcelino Botín, Realigraf, S.A.ISBN978-84-96655-23-2. Archived fromthe original(PDF) on 3 March 2016. Retrieved2 July 2010.
