DMI report WP311 - Data driven climate change adaptation Part B: National and local scale flood modelling as a basis for damage cost assessments:Final scientific report of the 2020 National Centre for Climate Research Work Package 3.1.1, Data-driven climate service (part B)

In light of climate change, which will inflict not only sea-level rise but potentially also more forceful extreme winds for some regions, there is a pressing need to assess the magnitude and occurrence statistics of future storm surges and their resulting impacts in terms of affected economic assets. This study employs different combinations of existing climate projection scenarios, return period statistics, future periods and sea-level rise assumptions to depict resulting damages from storm surges on a national scale and shown here per municipality. The methodology employs two tracks: 1) based on insurance payouts from previous storm surge events and 2) based on sales price information (postal code based). Further, the resulting damage assessment effects of using static sea-level rise, as for the national scale analysis, as opposed to a dynamical storm surge model, which is assumed as a more correct approach, is analyzed and discussed. In general and as expected, there is a positive correlation between the extremeness of the scenarios employed and time into the future and the resulting damages. The results from the mildest to the most extreme scenarios span +5000 to +9000 flooded buildings for the single-most flooded municipality alone. The insurance based methodology assumes equal payouts between regions whereas the sales price estimates are dominated by areas with higher property values such as the capital region. As also expected, the damages resulting from the dynamical storm surge modelling result in a reduced flood area compared to the static sea-level rise due to the underlying assumptions on duration.