Case study: influence of rivers

The Seine , Somme , Rhine and Meuse also influence our marine waters

The hypothesis that Belgian waters are a mix of water from the Channel and from the Scheldt Estuary is generally accepted by scientists. A study by scientists at MUMM, shows that this is not so simple: the rivers Seine-Somme and Rhine-Meuse have also a big influence on the Belgian seawater, sometimes even more than the river Scheldt . The influence of the rivers also changes with meteorological circumstances.

This hypothesis has been tested using a hydrodynamic computer model that simulates currents and salinity of the seawater. At each moment, the Belgian seawater is divided into 4 categories in function of the dominant influence of the ocean, the Seine-Somme, the Scheldt or the Rhin-Meuse.

The tests made by scientists of MUMM show that the Belgian waters are dominated by inflow of saline water from the Channel which mixes with freshwater originating mainly from the Rhine-Meuse with a much smaller contribution from the Scheldt Estuary and the Seine (and Somme).

This study shows that the protection of the quality of the marine environment is a transnational responsibility. The hydrodynamic model will be used to assess the results of the Water Framework Directive of the European Union.

The study was realised in the framework of the AMORE project (Advanced MOdeling and Research on Eutrophication) financed by Federal Science Policy.

When the contribution of rivers to the water mass is less than 1%, the water mass is considered to be "oceanic" and is represented in dark blue. In the opposite case where the contribution of rivers to the water mass is more than 1%, the river with the highest contribution is considered to be dominant. Each dominant river is represented by a different color: Scheldt red, Rhine-Meuse yellow, Seine-Somme: green and Thames light blue.

Origin of water mass of the Belgian waters (EEZ). Data are averages from the latest decennium (1993-2002).

For more information:

An animation shows for each week (1993-2002) which river (Scheldt, Rhine-Meuse, Seine-Somme or Thames) contributes the most in the Belgian waters.

Geneviève Lacroix, Kevin Ruddick, José Ozer, Christiane Lancelot., 2004. Modelling the impact of the Scheldt and Rhine/Meuse plumes on the salinity distribution in Belgian waters (southern North Sea). Journal of Sea Research, 52(3):149-163. For internal use only. Please note that this article can not be copied or spread (copyright).