flood modelling
     

Wollongong City Council commissioned specialist flood consultants, WBM, to prepare this Interactive Flood Model.  WBM have a history of working with Wollongong City Council on Flood Studies and Flood Impact Assessments in the area.

 

Computer flood models are used to estimate how rain ponds, infiltrates into the ground and travels overland into creeks and rivers.  The models then calculate how flood waters travel along creeks and rivers and how the water flows across floodplains and through urban areas.  They can predict the extent of area that may be flooded, the depth that the flood reaches, and how fast the water moves.

 

Flood models are used to simulate real flood events that have occurred.  If the amount of rain that fell during the storm was recorded at rain gauges within the catchment, this information is used to calculate flood depths for the storm.  The calculated flood depths can then be compared to recorded flood marks (e.g. watermarks on walls, debris lines, etc.) to assess how well the model is performing.  This process is referred to as model calibration.

 

Flood models are also used to predict the likelihood of flooding.  These floods are called design floods and are usually given a probability, for example, a one in a hundred year flood.  This information is useful to planners in Council who have to minimise the risk of flooding to new developments by setting controls such as minimum floor levels for houses.  For example, the building floor height must be 500mm above the 1 in 100 year design flood.

 

Flood models are a simplification of the real situation.  A variety of data are required as input to a flood model before it can be used.  Some of the data required are:
  • The height above mean sea level of the creeks and floodplains.  This information may be collected using ground or airborne survey methods;
  • ‘Roughness’ of the floodplain – this requires information about the land use; and
  • Details of any structures on the watercourses to be modelled. 
Click on the buttons on this page to find out more about flood modelling.