Catastrophe Management: Riverine Flooding

Abstract

Losses from natural disasters are on the rise and risk management options for lessening direct as well as indirect consequences are gaining in importance. Riverine flooding is one key concern and climate change is globally projected to increase intensity and frequency of flooding burden - albeit, due to numerous uncertainties there is only low confidence in projected changes. On the other hand, there is high confidence that today’s and future losses are rising as more assets and people are moving in harm’s way. The quantitative assessment of flood risk is complex, as such extreme event risk is characterized by few observations (low probability) associated with massive consequences (high impact), which by definition means substantial uncertainty around any estimates, particularly if future drivers, such as from climate change, need to be addressed as well. The methodology of choice is probabilistic catastrophe modelling, which combines hazard (flood intensity and frequency) with exposure (people and assets) and their vulnerability (susceptibility of exposed people and assets to incur losses for a given hazard). In order to properly account for uncertainty, we present three different catastrophe risk modelling approaches that outline the scope for possible changes in flood risk in Austria over the next 90 years. The analysis and findings are particularly relevant for Austria’s Natural Disaster Fund, which is the primary disaster loss financing vehicle in Austria. Large uncertainties between the different approaches and various limitations restrict our general conclusion as well as a full comparison between the approaches. However, we discuss possibilities to overcome these barriers in the future including suggestions how to arrive at more robust solutions in the face of such large uncertainties.