Regional analysis of multivariate compound coastal flooding potential around Europe and environs: sensitivity analysis and spatial patterns

In: Natural hazards and earth system sciences: NHESS, Band 21, Heft 7, S. 2021-2040

Abstract

Abstract. In coastal regions, floods can arise through a combination of multiple
drivers, including direct surface run-off, river discharge, storm surge, and
waves. In this study, we analyse compound flood potential in Europe and
environs caused by these four main flooding sources using state-of-the-art
databases with coherent forcing (i.e. ERA5). First, we analyse the
sensitivity of the compound flooding potential to several factors: (1)
sampling method, (2) time window to select the concurrent event of the
conditioned driver, (3) dependence metrics, and (4) wave-driven sea level
definition. We observe higher correlation coefficients using annual maxima
than peaks over threshold. Regarding the other factors, our results show
similar spatial distributions of the compound flooding potential. Second, the
dependence between the pairs of drivers using the Kendall rank correlation
coefficient and the joint occurrence are synthesized for coherent patterns of
compound flooding potential using a clustering technique. This quantitative
multi-driver assessment not only distinguishes where overall compound flooding
potential is the highest, but also discriminates which driver combinations are
more likely to contribute to compound flooding. We identify that hotspots of
compound flooding potential are located along the southern coast of the North
Atlantic Ocean and the northern coast of the Mediterranean Sea.