Communicating flood risk to the public by cartography

Flood risk communication plays an important role in risk management, because it can strengthen people’s risk awareness and can motivate them to take precautionary actions. To inform the public about flood risks, the use of flood maps is encouraged by the recent EU Flood Directive (2007/60/EC). Mapping flood risks deals with the challenges of representing risks in a way people can understand and interpret them correctly. In this contribution, the use of flood maps is discussed within risk communication. Attention is further given to the cartographic principles of flood mapping and to the role of the Internet in communicating flood risks via web cartography. Eventually, the state of the flood risk mapping in Flanders (Belgium) is discussed, considering the theoretical aspects previously handled

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

Uncertainty on coastal flood risk calculations, and how to deal with it in coastal management: case of the Belgian coastal zone

A coastal flood risk calculation estimates the damage by coastal flooding for a certain time horizon. Fivedifferent sources of uncertainty can be distinguished: unpredictability of the weather; uncertainty on theextreme value probability distribution of storm surges; unknown future values of economic growth rate,population growth rate, sea level rise rate and discount rate; limited knowledge of the behaviour of thecoastal system; limited amount of measurements about the state of the coastal system. From a preliminaryanalysis for the Belgian coastal zone it is clear that the combined effect of these different sources ofuncertainty results in a very large uncertainty on the calculated risk, namely a sigma of a factor more than10. Some important sources of uncertainty are impossible to decrease substantially by doing research ormeasurements. Therefore the only option for coastal management is to deal with these large uncertainties.It is suggested to use calculation results relatively, namely to compare scenarios of coastal management inorder to determine which scenario can best use an available budget for investment. Also it is concludedthat risk calculation results would best be compared as ratios between scenarios (in %), not as differences(in euro/year)

CLIMAR: evaluation of climate change impacts and adaptation responses for marine activities. Subdocument coastal flooding

Within the project CLIMAR an attempt is made to develop an evaluation framework for adaptation responses toclimate change induced impacts within the North Sea environment. The identification and quantification of all thepossible secondary impacts of climate change is handled on a sectoral level. The different case-studiesinvestigated in the framework of the research are fishery, tourism, sand and gravel extraction, the port ofZeebrugge and flood risks. This document gives an overview of all the different types of land occupation andinfrastructure within the coastal zone that might be subject to flood risks as a consequence of primary climatechange impacts

A GIS tool for flood risk analysis in Flanders (Belgium)

In the past decades, the low-lying region Flanders (Belgium) has fall victim to numerous flood events, causing substantial damage to buildings and infrastructure. In response to this, the Flemish government proposed a new approach which considers the level of risk as a way for safety measurement. Using geographical information systems, this evolution has lead to a comprehensive risk methodology, and more recently to the development of a flood risk assessment tool called LATIS. By estimating the potential damage and the number of casualties during a flood event, LATIS offers the possibility to perform risk analysis in a fast and effective way. This paper presents a brief overview of the currently used methodology for flood risk management in Flanders and its implementation in the LATIS tool. The usefulness of this new tool is demonstrated by a sequence of risk calculations, performed in the framework of climate change impacts on flood risk in Flanders