A GIS for flood risk management in Flanders

In the past decades, Flanders, a region of north Belgium that extends from the coastline inland (in northwest Europe), has suffered several serious riverine floods that caused substantial property damage. As Flanders is one of the most densely populated regions in the world, a solid water management policy is needed in order to mitigate the effects of this type of calamity. In the past, Flemish water managers chose to drain off river water as quickly as possible by heightening the dikes along the rivers. However, this method leads to a higher flood probability further downstream. Moreover, water defence infrastructure can always suffer from technical failures (e.g., breaching) creating even more damage than would have occurred if no defences were in place. In a search for a better solution to this recurring problem, the Flemish administration proposed a new approach in the 1990 s. This approach focuses on minimizing the consequences of flooding instead of attempting to prevent floods. To implement this approach, large amounts of data were gathered for the Flemish Region. Using a Geographic Information System (GIS), a risk-based methodology was created to quantitatively assess flood risk based on hydrologic models, land use information and socio-economic data. Recently, this methodology was implemented in a specifically designed GIS-based flood risk assessment tool called LATIS. By estimating the potential damage and number of casualties during a flood event, LATIS offers the possibility to perform risk analysis quickly and effectively. This chapter presents a concise overview of LATIS’ methodology and its implementation for flood risk management in Flanders