Recent flood events in Australia including the Brisbane flood have highlighted the need for more advanced flood forecasting techniques. In this matter, Blake Boulton and Terry van Kalken from DHI’s flood business area in Australia are calling for the application of hydraulic models. Their article published in the June issue of Water Engineering Australia magazine brings to light how these models could provide major improvements to flood forecasting in Australia.
As opposed to hydrology-based models currently in use, the hydraulic models offer three main assets:
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Real-time flood mapping
Flood forecasting based on hydraulic models are able to provide level and discharge information at any location within the floodplain. Predicted water levels can be mapped onto a land surface to provide forecast of flood inundation extents and depths.
Example of a flood map output for Grantham in Queensland
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Disseminating critical information
Through GIS processing techniques, the hydraulic model based flood maps can be interrogated to provide critical information such as evacuation routes, time and location of infrastructure flooding, population at risk, hazard, etc. This information could be easily disseminated into existing websites or tailor-made dashboards.
Concept diagram of computer-assisted river management
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Active river management
Current technologies allow for a more active role for the computer model in situations where dam or river structure operations are important for controlling flood events. These strategies can now be tested and optimised in real time, taking full account of current and forecast river conditions and rainfall.
The application of hydraulic models for flood forecasting has become possible in recent years due to increases in computer speed and optimisation of hydraulic model engines. In addition, in Australia, hydraulic models of most flood prone regions already exist and in many cases these can be incorporated into an automated flood forecasting system with only minor modifications, as well as into active river management systems.