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SEINE

Ancient: Sequana, French: Seine.

Length (km): 776
Drainage Area (km2): 78 650
Discharge (m3/s): 500
Countries: 2
Population: 15 000 000
Sea at Mouth: Atlantic
Ramsar Sites: 1

The Seine has its source on the Langres Plateau, at 471 meters altitude, in Burgundy about 30 km northwest of Dijon. Known as the river going through the French capital Paris, the Seine also flows through the city of Rouen and joins the English Channel not far from the city of Le Havre. Its name comes from a Roman goddess called Sequana who was worshipped 2000 years ago at the source of the river. This Roman name came from a Celtic word which meant “ similar to a snake”, as the Seine has the most sinuous course of all French rivers, especially between Paris and the Channel. Its main tributaries are the Aube (240 km), the Yonne (293 km), the Loing (160 km), the Essonne (90 km), the Eure (225 km), the Marne (525km), the Aisne (280 km), and the Oise (330 km) which has its source in Belgium.

The Seine’s run-off is relatively regular, in part due to dams and flood protection infrastructure. These have reduced flooding which historically was very important (1910, 1924, 1955, 1982, 1999-2000:). A monitoring system for floods is essential because exceptional flooding could be catastrophic for the region, not only for houses and infrastructure, but also for economic activity, streets, subways and railways.

The course and banks of the Seine are highly modified; the majority of its course is used for navigation (the Seine accounts for 50% of national river traffic). Numerous dams have been built on the Seine and its main tributaries. It is connected by canals to the Scheldt (also called the Escaut), Meuse, Rhine, Saône and Loire rivers.

The high level of industrialization and urbanization has a major impact on water quality in the watershed, especially in its centre where analysed results range between 'bad' and 'adequate' ratings. Water quality is directly altered by intensive agriculture, water treatment plant effluents and the presence of one of the biggest megacities of Europe (25% of the French population lives here on 12% of the national territory). The main problems are nitrate levels, contamination by pesticides, and sediment contamination by heavy metals like mercury, copper, cadmium, and lead, especially in the estuary. In spite of this degraded state, there has been real improvement since 1990 for phosphates, organic matter, and heavy metal concentrations. Moreover, the quality of the water is an important issue as the Seine supplies 80% of the potable water for Paris after treatment.

The Seine is an important habitat for eels, although their population is diminishing. In fact, trend is not specific to the Seine but is true of Europe as a whole.

The Banks of the Seine in Paris were added to UNESCO's list of World Heritage Sites in 1991.

Seine Basin Authority: www.eau-seine-normandie.fr