Forecasting Flash Floods - What Can You Do?

In recent times, flood forecasting systems have been successfully developed to allow floodplain and flood emergency managers to determine the affectation of impending flooding for larger river catchments. In such systems, both fallen and forecast rainfall can be used to determine likely river behaviour at some time in the future.

However, in “flashy” or “urban” catchments, successful forecasting and emergency management must be carried out prior to the commencement of significant rainfall. In such situations, the management of the uncertainty of likely rainfall volumes and intensities becomes critical, as does the ability to rapidly assess the implications of changing forecasts.

This paper explores some innovative approaches being used in Australia to inform decision makers managing “flashy” catchments. These approaches focus on leveraging readily available hydrologic, hydraulic and infrastructure spatial datasets, along with forecast rainfall amounts to rapidly provide real-time intelligence on what will be affected by the impending flood, such as:

• What could the flood look like?
• Who will be affected?
• What roads will be cut?
• What infrastructure will be affected?
• What is the sensitivity of the above to changing forecasts?