Flood risk assessment in european river basins—concept, methods, and challenges exemplified at the mulde river

Abstract

Flood risk assessment is an essential part of flood risk management, a concept that is becoming more and more popular in European flood policy and is part of the new European Union flood directive. This paper gives a brief introduction into the general concept and methods of flood risk assessment. Furthermore, 3 problems in the practical application of flood risk assessment, particularly on the river basin scale, are discussed: First, uncertainties in flood risk assessment; second, the inclusion of social and environmental flood risk factors; and third, the consideration of the spatial dimension of flood risk. In the 2nd part of the paper a multicriteria risk mapping approach is introduced that is intended to address these 3 problems.

Recommendations for the user-specific enhancement of flood maps

“…Merz et al (2007) as well as De Moel et al (2009) provide overviews on flood mapping techniques. Applications of flood risk mapping are described for the European (Barredo et al, 2007), national (De Bruijn and Klijn, 2009) or regional scale (Büchele, 2006;Kienberger et al, 2009;Meyer et al, 2009;Ebert et al, 2010).…”

“…In this respect some of the barriers of risk communication or shortcomings of maps can be identified (Fuchs et al, 2007;Steinführer et al, 2008;Meyer et al, 2009). Firstly, risk communication by flood maps is mostly organised in a one-direction top-down manner.…”

“…If consequences are taken into account, they are mostly expressed in monetary terms, such as risks to buildings and inventories. Other risk criteria, such as social and environmental effects, are often neglected, as well as other user-specific contents (Meyer et al, 2009). Thirdly, flood maps are often designed and visualised by those with a technical knowledge of mapping and/or flooding, and thus the maps present information in a way that cannot be easily understood by laypersons and/or that is not suitable for the respective needs of public authorities for risk and flood emergency management (Cronin, 2004;Fuchs et al, 2007;Holub and Fuchs, 2009).…”

How are flood risk estimates affected by the choice of return-periods?

“…Penning-Rowsell et al, 1994;Wind et al, 1999). Exposure is often represented by land use maps, whereby each land use class is assigned an economic value per hectare (Merz et al, 2007;Meyer et al, 2009). Finally, susceptibility is most commonly represented by so-called stage-damage…”

River flood risk in Jakarta under scenarios of future change

“…Finally the expected annual damage is calculated as the area under the exceedance probability-loss (risk) curve, whereby the area is estimated using a trapezoidal approximation (e.g. Meyer et al, 2009). …”