The direct use of radar satellites for event-specific flood risk mapping

A near-simultaneous satellite acquisition of a flood event on 12 December 2006 on the Dee River in Wales (UK) is used to illustrate the potential to develop standalone space-borne flood risk mapping techniques. Both the ERS-2 and ENVISAT satellites recorded the event close to flood peak and only 28 min apart. This unique opportunity enables the creation of a very rare but extremely useful observed data set for flood inundation studies. This letter illustrates how this unique set of space-borne radar images can be used for rapid flood risk mapping. An event-specific weighted hazard map was generated based on plausible flood area observations from an aggregation of widely applied image-processing techniques. This map can be further augmented to an event-specific fuzzy flood risk map by fusing the multi-algorithm ensemble map with vulnerability-weighted land cover vector data in a geographic information system (GIS) environment. The technique presented is fairly flexible and leads to a potentially useful data set for direct use in flood management.