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Model Simulations Of The Oder Flood Event In July/August 1997 
S.H. Müller-Navarra & K. Huber 
Bundesamt für Seeschiffahrt und Hydrographie 
Bernhard Nocht Strasse 78 
22359 Hamburg 
Abstract 
The Oder (Odra) flood transported large additional water masses into the Stettiner Haff (Zalew 
Szczeci~ski) area during a period of about one month. The dispersion of these water masses in 
the areas of Kleines and Großes Haff (Wielki Zalew) and in the southern Pomeranian Bight was 
monitored by physical/chemical measurements and biological observations. 
The BSH (Federal Maritime and Hydrographic Agency), with its operational model for the North 
Sea and Baltic Sea, carried out model simulations of Oder flood water dispersion in the Haff area 
and Pomeranian Bight under realistic meteorological conditions in order to provide criteria for 
monitoring activities and possible warnings. The model system is forced by meteorological 
forecast fields from the EUROPA model of the German Weather Service. The hydrodynamic 
model provides forecasts of water levels, currents, temperature and salinity distributions for the 
whole model area. The resultant data fields are stored together with the forcing meteorological 
fields, and are available as input fields for drift and dispersion simulations. 
The Oder flood transported an additional volume of 5 km 3 freshwater into Stettiner Haff and 
Pomeranian Bight, which has spread very slowly in the surface layer of the southern Baltic Sea. 
As a result of the model simulation, the temporal development of the event can be described as 
follows. First the eastern part of Stettiner Haff, the Großes Haff, filled with flood water, 
displacing "normal" runoff water from that area. After about a week, Oder water started to flow 
into the Pomeranian Bight. Its dispersion within Stettiner Haff was by no means uniform (Fig. 1). 
The Kleines Haff, for example, was not much affected at first. When large marked water masses 
had already left the Großes Haff area through the Swine (Swina) river, maximally only about half 
the Kleines Haff water was replaced by Oder flood water. In the Pomeranian Bight, the 
concentration was higher at the coast of Usedom - at least initially - than at the coast of Wollin 
(Wolin). After 30 August 1997, northwesterly winds caused "fresh" Baltic water to flow from the 
northern to the southern part of the Pomeranian Bight, pushing the water body marked by Oder 
water in easterly direction along the coast of Wohin. At the same time outflow began from 
Kleines Haff through the Peenestrom into the Greifswalder Bodden. 
Due to low atmospheric activity, and hence limited vertical mixing in summer, the proportion of 
freshwater in Baltic water reached about 50% in the southern Pomeranian Bight. Near Rügen, it 
fell below 10%. Short periods of stronger wind may cause major shifts of the water bodies 
concerned, and possibly marked concentration fluctuations at individual locations. The 
forthcoming stormy autumn season will quickly normalize salinity conditions in the Pomeranian 
Bight and cover up all traces of the Oder flood event in the Baltic.