The impact of scale on probabilistic flood inundation maps using a 2D hydraulic model with uncertain boundary conditions

Recent international flood events have demonstrated the large damage and potential loss of life that flooding can cause. In order to accurately quantify flood risk and how it may change in the future, we need to improve our understanding of the uncertainties associated with making such predictions. Improvements in remote sensing have facilitated the use of high resolution models; however, without consideration of the uncertainties, these models can produce spuriously precise predictions. This paper has explored this by assessing how changing the scale of flood inundation models impacts on probabilistic flood inundation and flood hazard maps for the Imera basin, Sicily. We have demonstrated that, although coarse scale models can perform just as well as fine scale models, the results are dependent on both grid scale and likelihood measure. Furthermore, these results have highlighted the uncertainty associated with flood inundation predictions and the need to consider these uncertainties when performing flood risk analysis.