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Dieren en planten

Water en land

Landforms   Rivers   

Mens en Milieu

Basin of the rivers feeding the North Sea, Google Earth -Ecomare

Rivers

Various rivers run into the North Sea. You can see where they lie and which countries drain into the North Sea. The major rivers are the Schelde from Belgium and France, the Rijn and Maas from France, Germany, Belgium and the Netherlands, the Thames, the Humber and the Tyne from England and the Ems, the Elbe and the Weser from Germany and Czech Republic.

  • Freshwater supply
    Ems, foto fitis, sytske dijksen

    Fresh water flows into the North Sea from all of these rivers. There are no major rivers which drain directly into the North Sea from France, but water from the Seine and Somme enter via the English Channel. Thirty percent of the supply of fresh water to the northern North Sea originates from Norway and Sweden. Several rivers in the north of Great Britain also run into the northern North Sea, such as the Forth and the Tyne.

  • Supply of materials
    industry along Merwede river, foto fitis, sytske dijksen

    Besides water, rivers discharge mud, nutrients and pollutants are discharged into the North Sea and Wadden Sea. The supply via the rivers fluctuates per season and per year. This fluctuation influences the salt level in the North Sea. The supply of mud via the rivers is much less amount-wise than what is transported via the Atlantic Ocean. However, river mud is often very contaminated. Many contaminants sink to the bottom at the river mouth because of the slower current Sometimes the materials react with materials present in the seawater. Slowly but surely, these contaminants spread from the river mouths to other places. When the waterways are dredged, and the material is dumped in depots at sea, this process of spreading pollution is sped up. Fortunately, most of the rivers have become much less polluted in the past dozens of years. The most important reason is that dumping dangerous toxic waste is forbidden.

    Supply of polluted materials into the North Sea via the Rijn (in ton per year)
    materialsupply 1980supply 2000 (% of 1980)reduction
    cadmium 18 5,5 (31%) 69%
    copper 500 240 (48%) 52%
    lead 320 150 (47%) 53%
    zinc 2000 810 (41%) 59%
    PCBs 0,22 0,08 (36%) 64%
    PAHs 2,1 2 (95%) 5%
    source: directie Noordzee 2003

    From the table above, the greatest success of reduction has been with cadmium and PCB pollution. Copper and PAHs remain difficult materials and the discharge of other heavy metals has been more than cut in half.