Accuracy of pan-European coastal flood mapping

Coastal flood maps covering the whole European continent have become available in recent years. However, their ability to complement or replace high-resolution local flood maps was not investigated so far. In this paper we compare pan-European estimates of extreme sea levels and coastal flood extents at given return periods with observations and high-resolution reference maps. The analysis is done for two pan-European assessments and one global study. We find that whereas the models have good accuracy in estimating storm surge heights, large disparities exist between the large-scale flood maps and four local maps of flood extents from England, the Netherlands, Poland, and France. Moreover, the accuracy of the underlying digital elevation model and assumptions about flood protection existing in a given area influence significantly the results. In addition, the first pan-European projection of temporal trends in the size of flood zones is presented, with and without assuming flood protection levels.