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163 Chapter 7 The Flood Maps case As stated in Chapter 3, this book examines the relationship between process structure and spatial enablement at two levels: the inter-organisation case level and the intraorganisational embedded case level. The present chapter discusses the Flood Maps case, and is organised in the following way. The first section presents a general overview of the Flood Maps case. The second section describes the inter-organisational flood mapping process, in terms of spatial enablement, process structure and demands.The third section zooms in on the intra-organisational level. Finally, a comparative analyses of the six embedded cases of the Flood Maps case is presented in the fourth section. 1 Case description This fourth case refers to the process of compiling, updating, using and distributing flood maps. The process of flood mapping is part of the Integral Water Policy of the Flemish Government which is described in a Decree with the same name (VMM, 2007).The Decree has been further elaborated in the Water Policy Memorandum which integrates the qualitative as well as the quantitative aspects of the management of the water system in view of a sustainable usage of water by different sectors of society (CIW, 2005). One of the key principles of the Decree and the Memorandum is the concept of Space for Water. Water excess and water shortage are seen as two aspects of the same problem and are therefore treated in an integrated manner. This is done through the application of the principle of Holding-Storing-Discharging the water. This means that water is kept as long as possible at the place where the rain falls (e.g. by maximising infiltration in the soil or by using it directly), when necessary it is buffered at several places along the river network (e.g. in controlled flooding areas), and finally the water is discharged as slowly as possible through the river system. The first sub-process of the flood mapping process is the collection of information on flood events, the delineation of these events and the integration in the map of recently flooded areas (ROG). The most recent version of this map includes all the recent flood events since 1988. In order to make the map usable at parcel level, it was corrected by using a detailed Digital Elevation Model (DEM) of Flanders. In practice the ROG map is highly dynamic. Each time there is a new important flooding event, the newly flooded areas are delineated as precise as possible and added to the existing map (although separate maps of the major recent events exists as well). If the event concerns a major flooding, then it is decided whether a helicopter flight is organised or not, during which aerial photos are taken which are used to delineate the flooded area. In other cases, information is gathered in the field on the basis of topographic or other maps, with pictures and other information to illustrate the event. An example of such a recent major event is the flooding in many parts of Flanders in December 2010 and January 2011. The information of the flooding events are gathered by the major water management organisations (Flanders Hydraulics Research and the Flemish Environment Agency), but also by provinces, municipalities or other water management authorities at the local level 164 (such as the Water Boards). Citizens can also provide information about a local event. Fire brigades can collect their own information on smaller events as well. This is often done in the form of addresses without a precise delineation of the flooding. The second sub-process of the flood mapping process comprises the mapping of modelledfloodingareas.Severalmodellingtechniquesareusedbydifferentorganisations. The models simulate the water level and discharge, as well as the areas with a certain flooding risk.The models result in maps of modelled flooding areas (MOG).The MOG maps are very dynamic. New series of climate data, changes in the hydrographical network, or the introduction of new infrastructures will all have an impact on the modelled flood risk. The major water management authorities (Flanders Hydraulics Research and the Flemish Environment Agency) are using modelling applications, as well as some provinces. Even municipalities and water boards might perform simulations for specific areas. The third sub-process is the delineation of the flooding areas as defined by the Decree on the Integral Water Policy. These are defined as areas which are bordered by dykes or valley borders that can be flooded at regular intervals – controlled or uncontrolled – and thus can function...

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