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4 3 2 / P I L O T C A S E S T U D I E S : A F O C U S O N R E A L - W O R L D E X A M P L E SSeine-Normandy Basin, FranceTHE SEINE-NORMANDY BASIN district in the north-west of France coversan area of about 97,000 square kilometres (km 2 ), nearly 18 percent ofthe country’s total surface area. It is made up of the drainage basins ofthe Seine River and its tributaries, the Oise, Marne and Yonne, and those ofNormandy’s coastal rivers.General ContextThe land is relatively flat with altitudes generally under 500 metres. The climate is oceanicand temperate with an average annual rainfall of 750 millimetres (mm) and an averageannual potential evapotranspiration of 500 mm. Annual rainfall varies between 300 and1,600 mm, depending on the area. In Paris, it varies from 400 to more than 800 mm fromyear to year. The average monthly temperature in Paris is between 2.5°C (in January) and24.6°C (in August). Periods of freezing temperatures are short along the coast in the west,but lengthen as we move towards the eastern edge of the basin.Map 19.1: Locator mapAtlanticOceanUNITEDKINGDOMIRELANDSeine-NormandybasinFRANCESPAINBELGIUMGERMANYLUXEMBOURGSWITZERLANDITALYSource: Prepared for the World Water Assessment Programme(WWAP) by AFDEC, 2002.GeologyThe Seine-Normandy basin includes a large portion of thesedimentary Paris basin. The geological structure of the Paris basinresembles a stack of ‘saucers’ with the most recent layers (Tertiary)outcropping in the centre and the oldest layers (Mesozoic)outcropping on the outer edges of the basin. These layers overliethe Hercynian bedrock (Palaeozoic) that outcrops in the westernpart of the basin. This type of geological structure containsnumerous aquifers of extremely varying size and structure (alluvial,sedimentary and fractured aquifers). In the Paris basin, about ten ofthese aquifer formations are very important in terms of usage.Leached brown soil covers the western part of the basin. Thereis a thinner layer of acid brown soil, eutrophic brown soil andcalcareous soil on the eastern edge of the Paris basin and in LowerNormandy. The rendzina soil found in many places at the base ofhills is used for vine growing in the Champagne region.Population densityThe Seine-Normandy basin has an estimated population of17.5 million people, 80 percent of whom live in urban areas, mostof which are located along the basin’s rivers and in the Paris region(located approximately in the centre of the basin). PopulationTable 19.1: Hydrological characteristics of the Seine-Normandy basinSurface area of the basin 97,000 km 2Annual precipitation 750 mm/yearAnnual potential evapotranspiration 500 mm/yearAverage discharge in the coastal rivers of Normandy 125.8 m 3 /sAverage discharge in the Seine River 460 m 3 /sdensity in the basin varies greatly. The Paris suburbs are nowspreading into Upper Normandy. The Ile-de-France region aroundParis is the most popular tourist destination in France and has, forexample, 35 million foreign-tourist-nights per year. The populationsof some of the departments along the Normandy coast are alsosubject to very high seasonal variations.EconomicsEconomic activity in the Seine-Normandy basin is dynamic. Industrialproduction in the basin alone accounts for 40 percent of domesticproduction, and includes 60 percent of France’s automobile industryand 37 percent of its oil refining industry. There are agro-foodindustries located throughout the basin, whereas heavy industry(chemical, oil, paper, metallurgy) is concentrated in the Lower SeineValley and the Oise Valley. There is a wide range of economicactivity, in terms of both size and diversity, in the Paris regionalone. The trades, service and commercial sectors, an integral partof the urban fabric, also flourish due to the high population density.The basin also has a prosperous farming industry, with extensivefarming on vast plains and the renowned wine-producing regions ofChampagne and Burgundy. Sixty percent of the surface area of thebasin is used for agriculture, and 80 percent of France’s sugar,75 percent of its oil and protein seed crops and 27 percent of itsbread grain comes from this region. Since 1970, farming practices inthe basin have followed the global trend towards large industrialcrops with high added value (sugar beets, rapeseed, potatoes) witha concentration of cereal crops in the south-west and livestockproduction on the edges of the basin.