Experiences from storm surge flood damage modelling driven by local decision makers

A large part of the current research on flood damage costs build on a similar methodological framework across studies that integrates climate data (hazard), flood modelling (exposure), damage cost assessments (impact) and calculate risks as the product of the likelihood of events and their consequences. A key question here is how relevant such a methodological framework is in relation to the perspectives of decision makers on establishing safe standards for investments in climate change adaptation in the context of the large uncertainties surrounding both estimates of the extreme event probability and on the damages of these. Particular issues that are often raised by decision makers are related to how extreme precipitation and storm surge levels could be, and on how well the damages of such events are represented in damage estimates recognizing the limitations of monetary evaluations as well as risk preferences of decision makers.

The paper is addressing how the gap between conventional approaches applied to hazard and impact modelling and the needs and practice of decision makers can be diminished based on the experiences with the development and application of a detailed object based spatial DamageCost Model for storm surges. The model has been widely applied by Danish local governments as a basis for developing adaptation plans. Soon after the first version of the model was released, local Danish governments took over leading the model development from a user perspective in a close ongoing dialogue with DTU and the engineering consultants LNH Water, which through several projects, including the EU ARSINOE project continue to support further technical development and model use.

Experiences from how the model development have been inspired by decision maker perspectives gained through model use are reported based on case studies for the Danish cities of Esbjerg, Odense, and Aabenraa.