Regional flood impact assessment based on local land use patterns and sample damage records

Increasing land consumption and land demand particularly in mountainous regions entail further expansion of settlements to known hazard-prone areas. Potential impacts as well as regionally defined levels of `acceptable risk´ are often not transparently communicated and residual risks are not perceived by the public. Analysing past events and assessing regional damage potentials can help planners on all levels to improve comprehensive and sustainable risk management. In this letter, a geospatial and statistical approach to regional damage cost assessment is presented, integrating information on actual conditions in terms of land use disparities and recorded damage data from a documented severe flooding event. In a first step building objects are categorized according to their function and use. Tabular company information is linked to the building model via geocoded postal address data, enabling classification of building types in terms of predominant uses. For the disaster impact assessment the flood plain is delineated based on post-disaster aerial imagery and a digital terrain model distinguishing areas of long and short term flooding. Finally, four regional damage cost assessment scenarios on different levels of detail are calculated. The damage cost projection relies on available sample building-level damage records, allowing rough damage averaging for distinct building uses. Results confirm that consideration of local land use patterns is essential for optimizing regional damage cost projections.