The Oder Estuary - IOW

Schernewski, G. & T. Dolch (eds.): The Oder Estuary – against the background of the European Water Framework
Directive. Marine Science Reports 57 (2004). ISSN: 0939-396X.
Der Einfluss des Schifffahrtskanals auf den Stoffhaushalt des
Oderhaffs
The impact of the shipping channel on the material balance of the
Oder Lagoon
Marion Minning
Kronskamp 11, D - 24119 Kronshagen, Germany
Email: marion.mi@gmx.de
Summary
The aim of this article is to assess the impact and the function of the shipping channel and the
regular dredging of this channel on the water quality of the Oder Lagoon water. The primary
questions are:
Does the regular dredging mean a relevant nutrient removal from the ecosystem Oder Lagoon?
What does that mean for the trophic status of the Lagoon?
What is the impact of the planned deepening of the channel on the material transport and
sedimentation processes in the Oder Lagoon?
The Oder river has a catchment area of 118.861 km² and flows at the border of Germany and
Poland. Before reaching the Baltic Sea it disembogues into a large shallow lagoon named the Oder
(Szczecin) Lagoon. The lagoon is characterized by a low depth of about 3.8 m. A deeper shipping
channel with a mean depth of 10.5 m is dredged into it, linking the Swina Strait with the Szczecin
harbour. Because of a high sedimentation rate in the lagoon, regular dredging of the channel is
necessary to keep its depth. Each year lots of nutrients and heavy metals are taken out of the lagoon
with the dredging material.
To answer the questions, eleven sediment samples from the bottom of the shipping channel were
analysed on their geochemical and mineralogical components and models of the flow field were
made with FemFlow2D. These analysis have shown that the sediment of the shipping channel is
polluted with nutrients like phosphorus and nitrogen and heavy metals like lead and copper. The
analysis have also shown that an important part of the river load spends a few weeks in the Oder
Lagoon and before it finally gets deposited on the bottom of the shipping channel.
The results of this survey show that the major part of the nutrient and heavy metal load of the Oder
river is taken out of the lagoon within the dredging material. This plays an important role for the
material balance of the Oder Lagoon and has a significant impact on the eutrophication status of the
Lagoon.
So, the shipping channel plays an important part with respect to water quality protection of the
Oder Lagoon and finally of the Baltic Sea.