Flood exposure of environmental assets

Abstract. Environmental assets provide important benefits to society and support the equilibrium of natural processes. They can be affected by floods, nevertheless, flood risk analyses usually neglect environmental areas due to (i) a lack of agreement on what should be considered as an environmental asset, (ii) a poor understanding of environmental values, and (iii) the absence of damage models. The aim of this work is to advance the understanding of environmental exposure to floods by first identifying asset typologies that could be considered in flood risk analyses and second, by introducing a method, named EnvXflood, to estimate flood exposure of environmental assets. The method is structured around three levels of detail requiring increasing information, from a fast and parsimonious analysis suitable for regional assessment to a detailed ecosystem-service-based site analysis. Exposure focuses on the social and environmental value of the assets. Social values were investigated by means of a survey. The method was tested on three case studies in Italy (Tuscany region, Chiana, and Orcia basins). The Ecosystem Services weighting highlights the leading importance of the biodiversity-supporting service. The results of the analyses show that the environmental assets related to water, such as rivers, lakes, and wetlands, are the assets most exposed to floods. Notwithstanding, commonly they are not considered as exposed assets in the usual river management practices. Further research should aim at consolidating the asset typologies to be included in environmental exposure analysis and their social and ecological value, moving towards a coherent understanding of environmental flood impacts.