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GUADIANA

Arabic: Wadi Ana, Portuguese: Guadiana, Spanish: Guadiana.

Length (km): 778
Drainage Area (km2): 66 800
Discharge (m3/s): 80
Countries: 2
Population: 4 000 000
Sea at Mouth: Atlantic
Ramsar Sites: 2

The Guadiana River basin has a total drainage area of 66 800 km2 of which 11 580 km2 are located in southeastern Portugal. It constitutes one of the three main drainage units of the Iberian Peninsula shared between Portugal and Spain. The River flows westward through southcentral Spain and southeastern Portugal to the Gulf of Cádiz and the Atlantic Ocean.

The land use is predominantly rural. Of the total needs for irrigation and domestic water supply in the Guadiana basin, 19% are in Portugal and 81% in Spain, while 25% of the average annual discharge is generated in Portugal and 75% in Spain.

The Portuguese section of the River has a slight water deficit, aggravated in extremely dry years. The river discharge is very irregular.

A major part of the water quality problem comes from agricultural practices, where nitrates, phosphates and phytopharmaceutical products such as pesticides abound. The loads stemming from agricultural activity combined with the summer high temperatures periodically stimulate algae blooms. Eutrophication is affecting several manmade lakes.

The main problems within the river basin are the overexploitation of the aquifers in the upper river basin for agricultural use, the agricultural contamination, and fragmentation by dams. The severe drying-out of the upper river and associated wetlands, such as the Tablas de Daimiel National Park, has aggravated water management problems in the river basin. The current solution is water transfer from the Tagus river basin, which has resulted in the introduction of a number of alien species that endanger the local endemic fish species in the Guadiana.

Point source pollution from industries, mining, sewage treatment plants, landfills, and others, also cause major pollution problems.

Another type of pressure on the ecological status and water quantity is the large number of dams built for irrigation both upstream in Spanish territory and on the Portuguese downstream side. There are 1,824 dams in the Guadiana river basin, of which 86 are major dams that retain about 150% of the average annual rainfall. The Alqueva is the largest and one of the newest dams in the Iberian peninsula.

In Spain, the River Basin Authority is drafting with the farmers - while excluding other stakeholders - an “Upper Guadiana Plan”.

The CADC (Commission for the Application and Development of the Albufeira Convention between Portugal and Spain) is particularly active in the Guadiana river basin. There are a number of Working Groups and Sub-commissions working in the Guadiana and several joint studies have been executed on the transboundary
river basin.

Alqueva Dam

The Alqueva dam, located on the Portuguese section of the Guadiana River, is one of the biggest dams in the Iberian Peninsula. It has given its name to the Alqueva Dams Scheme.

The first plans to create a water reservoir in the Alentejo region of the Guadiana River were made nearly 100 years ago. The project was prepared in 1957, as part of the the Alentejo Irrigation Plan.

The preliminary work in the 1970s lasted only two years, during which the downstream and upstream cofferdams, the provisional deflection tunnel, and access and support infrastructure were built.

After interruptions, construction began in 1998. The Alqueva reservoir began filling in February 2002.

The Multipurpose Alqueva Project is a regional development project. It is a hydroelectic facility located in the heart of Alentejo, the main target region to benefit from the objectives of the Project.

The Alqueva reservoir is 83 kilometres long and covers an area of 250 km2 (63 km2 in Spain). Its shoreline extends for approximately 1 100 km. The total capacity of the reservoir is 4 150 billion m3 with a useful capacity of 3 150 billion m3.

National and regional environmental NGOs are represented on the CAIA (Commission for the Environmental Monitoring of Alqueva Dam).

CONFEDERACIÓN HIDROGRÁFICA DEL GUADIANA - Spain: www.chguadiana.es

Instituto da Água - Portugal (INAG): www.inag.pt