Modelling and mapping of urban storm water flooding - Communication and prioritizing actions through mapping urban flood resilience Modélisation et cartographie des inondations en zone urbaine : actions de communication et gestion des priorités en appui sur la cartographie de la résilience des villes face aux inondations

Due to climate change, urban areas will flood more frequently. Short peak rainfall intensities will exceed the storm water drainage capacity and cause flooding of streets and possibly buildings and homes. In order to make cities more resilient to flooding more space for water at ground level is needed. The main problem is how to convince other professionals, concerned with planning and maintenance of urban areas, of the importance of space for water. To support this view, a GIS-based method for mapping urban storm water has been developed. Based on an accurate DEM the maps provide insight in the above ground flow and storage of water. Due to its straightforward concept the method is easily understandable for all stakeholders in the urban management. This promotes the collaboration of those stakeholders in finding and maintaining solutions. For the city of Apeldoorn in the Netherlands, which suffered flooding from extreme rainfall in July 2009, this method has been used to search for above ground measures against flooding. In order to maximize the possibilities of interaction between professionals of different spatial fields (water, green, road) the maps were presented in a workshop using a touch table. This appeared very successful and this method is therefore used for many cities in Holland and even outside of the Netherlands like Bergen (Norway) and Rio the Janeiro.