Floods in urban areas cause considerable economic losses and affect many people. Measures for flood mitigation in urban areas are primarily of an engineering character, however, existing city infrastructure very often restricts the introduction of appropriate new constructions. The city of Gdañsk is situated at the mouth of the Vistula river, on the area, which forms Vistula delta. It is the most flood-prone agglomeration in Poland. Now there are three possible flood sources. The first is from the moraine hills, in case of intensive precipitation. This area was recently rapidly urbanized. The second source of flood is from the Gulf of Gdañsk caused by storm surges and the third is from main channel of Vistula river in case of very high discharge or ice jam.
The city of Gdañsk is situated within a complicated system of rivers and channels called Gdañsk Water Node (GWN). It is influenced by the discharge of rivers flowing from the moraine hills in the west, and from possible storm surges in the Gulf of Gdañsk. In July 2001 a severe flash flood, arising for the first time from the moraine hills, caused by very intensive rainfall, hit Gdañsk. In the paper description of the operation of GWN, the flood cause, run and damages are presented. Description of measures, which were proposed to mitigate influence of a similar flood in the future are given. These measures were proposed on the basis of detailed field measurements, hydrologic analysis, hydraulic calculations and possible hydro-engineering developments.
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MAJEWSKI W. et al. 2003, 2004: The model of water distribution in the Gdañsk Water Node for flood protection in the Martwa Vistula catchment, Institute of Hydro-Engineering Gdañs, (unpublished internal report, in Polish).
MIKE 11, Hydrodynamic Module, DHI Water and Environment.