Objectives

There are no longer any doubts that the climate change will lead to more extreme weather conditions. As a consequence the risk failure of coastal flood protection structures will increase. The City of Hamburg has already reacted and has raised their dikes by more than 80 cm in the last years. But this improvement does not guarantee a protection against extreme flood which might cause a dike failure by breaching or overflow. Therefore there is a strong need to include such failure scenarios into the urban land use planning and development strategies and to prepare adequate emergency and rescue plans.

For the City of Hamburg these new findings are of great relevance for the political programs as the City fosters the “Growing City” and wants to develop new urban areas by “The Jump over the River Elbe”, and by making use of the deep lying open space on the island Wilhelmsburg and the former harbour areas of HafenCity, Graasbrook and Reiher Stieg. While the island Wilhelmsburg is surrounded by a ring dike the former harbour areas are without any public flood defence system. Thus these areas are regularly flooded and the stakeholders are obliged to protect their buildings by sealing or raising the surrounding area to a specific level, the design flood stage for all flood prone urban areas.

All planning concepts are based on the functioning of the flood defence structures and do not consider the occurrence of an extreme climate situation which leads to flood stages above the design flood. Therefore the consequences of filling up the polder bottom in these new urban areas on the island Wilhelmsburg are not known.

The research concentrates on the following main goals:

• Exploration of the present practice of urban planning in flood prone areas and development of new methods and strategies of spatial planning (in combination with a changed public perception of flood-risk), structural preparedness and emergency planning to protect them against extreme floods which are beyond the design flood and thus lead to a failure of the flood defence system.
• Discussion of the problem within an international project team of the cities of Dordrecht/Netherland, London/UK and Hamburg.
• Selection of similarities and development of general guidelines for urban planners and emergency rescue groups to deal with extreme floods.
• Development of a scientifically based information-system to simulate extreme flood events, to determine the consequences of flooding and to analyse the efficiency of spatial planning measures, infrastructural and structure related measures as well as the potential of an improved emergency plan.

The applicability and efficiency of the new planning and emergency strategies as well as the new computer based information-system for extreme flood management will be studied at the polder area of Wilhelmsburg and at the urban development areas of HafenCity, Grasbrook and Reiherstieg which have individual flood defence systems.