General information

Location Greve, Denmark
Area 60 km2
Population 40.819 (as of January 2013)

Overview

The study area covers the coastal area of Greve in eastern Denmark. It is a sub-urban area around 60 km2 in size and located about 20 km south of Copenhagen. Several streams in the area drain into Køge Bay in the East. These streams are integral parts of the drainage network, which is comprised of dense connections of underground pipes, open channels, manholes, basins, and outlets to the bay. The municipality has about 9 km of coastline along which the area is densely built-up with residential settlements and characterized by relatively flat terrain with elevations ranging from 2-6 m.

Problem Description

Understanding of the flood problem in the Greve area calls for holistic analyses of the interaction between the rural areas surrounding the city; urban drainage system (sewers and urban rivers) in conjunction with the storm surges and the associated impacts on the urban water system due to backwater preventing drainage into the sea. This includes modelling and understanding of joint probabilities between extreme rainfall and storm surges today and in the future.

Historic Events

The area has a flood history including flooding from extreme rain events and flood from the sea. Much has been done to reduce the flood risk due to extreme rain events, but it can never be eliminated. Coupled rain events are a serious concern for the city today and under a future climate. In July 2007, a series of rain events with a joint probability of occurrence of 500 years caused severe flooding in Greve. In addition to extreme rainfall, Greve is also vulnerable to flooding from extreme sea levels along its coast. In the more distant past the area has been flooded due to very serious storm surges, e.g. the 13th October 1760 with a water level of 3,7 m. If any of these to floods are repeated today they would cause very serious damages.

Research focus

Collaboration with other work packages in PEARL are as follows:

  • WP2: Fully integrated modelling (Ground water; sewers; river and the sea) for today and under future climate conditions;
  • WP3: Mapping of flood costs and vulnerability should be carried out incl. uncertainty and robust decision making for investments to reduce flood damage, public health impact assessment . Holistic risk assessment;
  • WP4: A sufficiently fast real time warning system (incl. real time data assimilation on water levels) should be established and evaluated for real life conditions;
  • WP5: Evaluation of engineering measures (focusing on including EWS), FRI.