Spatio-temporal clustering of extreme floods in Great Britain

ABSTRACT

Quantifying the tendency of flood events to demonstrate clustering in time and space is crucial for flood risk assessments. We analyse the temporal (TC) and spatial (SC) coherence of floods in 554 catchments over Great Britain. TC was assessed using the dispersion-index and Conway-Maxwell-Poisson regression, with both methods applied to aggregation windows of 1–5 years. SC was investigated using the flood susceptibility index. Results show that i) most of the UK peak floods are overdispersed and ii) a positive relationship exists between winter mean North Atlantic Oscillation anomalies and the annual number of peak floods across western Britain. The susceptibility to widespread floods is higher for the southeast parts of Britain and for the Clyde-Forth valleys, and it increases with catchment permeability and with the influence of lakes/reservoirs. These findings are relevant to enhance existing flood hazard estimation methods and, in turn, will lead to more realistic flood risk quantification.

KEYWORDS:

• flooding
• flood spatial dependency
• flood temporal clustering

Editor A. Fiori; Associate Editor I. Prosdocimi

Editor A. Fiori; Associate Editor I. Prosdocimi

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/02626667.2024.2367167

Acknowledgements

The contribution by Cecilia Svensson was supported by the UK Natural Environment Research Council (NERC) National Capability award NE/R016429/1, UK-SCAPE (UK Status, Change and Projections of the Environment), https://uk-scape.ceh.ac.uk.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The dataset used in the study is freely available at https://nrfa.ceh.ac.uk/peak-flow-dataset