Correlation among Drivers Affects Projected 21st Century Changes in Compound Floods over European Coasts
Abstract
Compound flood hazards in coastal areas, which are expected to aggravate in a changing climate, result from the concurrent or successive (d-day lagged) occurrence of high coastal water levels (HCWL) and high river discharge. Although recent attribution studies, at local to continental scales across Europe and several other regions, have shown compounding effects of HCWL (or storm surges/tides) and fluvial floods (or extreme precipitation as a proxy for fluvial discharge) in the present-day climate, only a handful of studies have projected future changes in compound floods. However, their different spatial scales, time periods, variations among considered drivers and the nature of extremes render it difficult to derive generalizable trends in projected extreme. Further challenges to future compound flood hazard assessment include difficulties in projecting individual drivers at the spatial resolution of coastal urban topography. Here we quantify projected changes in compound floods over northwestern Europe during the 2050s (2040-2069) in the high (RCP8.5) emission scenario. We combine high-resolution storm surge projections with a probabilistic sea level rise scenario to estimate future HCWL and use a global hydrological model to project fluvial floods. We model interdependence among compound flood drivers with bivariate copulas, which allow us to assess the overall dependence as well as the upper tail dependence. Our findings point to a weakening in the dependence strength for 93% of the sites. Further, we project a decrease in compound flood hazard for ~66% of the sites. The projected slowdown in compound flood hazard might be a consequence of weakening in the strength of dependence between storm surge and peak discharge, owing to a decrease in wind speed associated to poleward shifts of the North Atlantic jet. Regions with higher future hazard are concentrated along the low-elevated coasts of Great Britain and a few parts of Scandinavia.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMNH024..01G
- Keywords:
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- 4306 Multihazards;
- NATURAL HAZARDS;
- 4313 Extreme events;
- NATURAL HAZARDS;
- 4328 Risk;
- NATURAL HAZARDS;
- 4332 Disaster resilience;
- NATURAL HAZARDS