Articles | Volume 16, issue 2
Research article
29 Feb 2016
Research article |  | 29 Feb 2016

Quantifying the effect of sea level rise and flood defence – a point process perspective on coastal flood damage

M. Boettle, D. Rybski, and J. P. Kropp

Abstract. In contrast to recent advances in projecting sea levels, estimations about the economic impact of sea level rise are vague. Nonetheless, they are of great importance for policy making with regard to adaptation and greenhouse-gas mitigation. Since the damage is mainly caused by extreme events, we propose a stochastic framework to estimate the monetary losses from coastal floods in a confined region. For this purpose, we follow a Peak-over-Threshold approach employing a Poisson point process and the Generalised Pareto Distribution. By considering the effect of sea level rise as well as potential adaptation scenarios on the involved parameters, we are able to study the development of the annual damage. An application to the city of Copenhagen shows that a doubling of losses can be expected from a mean sea level increase of only 11 cm. In general, we find that for varying parameters the expected losses can be well approximated by one of three analytical expressions depending on the extreme value parameters. These findings reveal the complex interplay of the involved parameters and allow conclusions of fundamental relevance. For instance, we show that the damage typically increases faster than the sea level rise itself. This in turn can be of great importance for the assessment of sea level rise impacts on the global scale. Our results are accompanied by an assessment of uncertainty, which reflects the stochastic nature of extreme events. While the absolute value of uncertainty about the flood damage increases with rising mean sea levels, we find that it decreases in relation to the expected damage.

Short summary
We provide simple functional expressions to characterise the development of coastal flood damage for rising mean sea levels as well as implemented flood protection levels. Furthermore, we are able to quantify the aleatory uncertainty of our estimates. All results are mathematically proven and their usability confirmed by employing two case study regions. Thus, we gain fundamental insights into the interplay of coastal flood damage, the mean sea level, and flood defence.
Final-revised paper