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The Flood in the Oder River 1997 - Impact on the Water Quality 
Albrecht Müller 
Federal Institute of Hydrology (BfG) 
Branch Office Berlin 
Schnellerstrasse 140 
12439 Berlin 
Abstract 
During the Oder River flood in July/August the Federball Institute of Hydrology, Branch Office Ber 
lin continued its study programme of suspended material at the stations FrankJfurt/O, river km 584, 
and at Schwedt, river km 690, which had started in 1996 [1]. The samples were taken by a centrifuge 
at the site or by water samples [2]. Investigations of Oder River sediments in the middle Reich have 
been made since 1994 [3]. 
The nutrient concentrations in suspended solids during the flood period show that the maximum 
concentrations cover ranges about 9 g P/1 and 38 g N/l, what is 2 and 5 times higher than the con 
centrations observed in June 1997 before the flood. The organic content increased in a similar man 
ner as nitrogen and reached a maximum at 230 g/kg. This corresponds to an accumulation factor of 
about 4 with regard to the natural conditions. 
In the discussion of the results, the following effects have to be taken into account. With increasing 
water level material from the river banks is transported upstream. Inundated communal wastewater 
treatment plants gave addional nutrient contributions. Flooding agricultural areas led to a remobi 
lization of fertilizers from the soil. 
On the flooded areas high bioproduction was observed in the water due to the rich nutrient supply. 
This fact explains the increase in organic carbon content by biogenic compounds. In the sum of these 
effects, the nutrient concentration increased during a relatively long period. 
For heavy metal determination in suspended solids, the fine-grain fraction below 20 pm was used in 
order to correct the grain-size effect. A comparison between Franfurt/O km 585 and Schwedt km 
690 should indicate posible influences of the Warthe River as the main tributary on this reach. On the 
basis of the results of 1996, the concentrations of the elements were found to be comparable with the 
only exception of cadmium, so that an input of Cd may exist upstream of Frankfurt/O 
A comparison between the flood situation and normal condition at both sites shows that for the ele 
ments Pb, Cu, Zn and Ni an accumulation factor of about 2 can be estimated for the flood event 
against the averaged values of 1996. 
These increase could be caused by transport of contaminated sediment from the upstream river banks 
and by flooded industrial areas. In this upstream river reach contamination can be expected from the 
mining and smelting operations at some industrial centres between Katowice and Glogow. 
A comparison between concentrations of the middle Oder River reach and the Middle Elbe River at 
Wittenberge (km 455) shows, that most elements have comparable levels with the only exception of 
cadmium. Since the beginning of the 1990s a remarkable reduction of contamination in the Elbe Ri 
ver has been observed due to the changes in the economic structure in central East Germany. In 
contrast to this, the concentrations in the Oder River remain unchanged in this period.