Articles | Volume 21, issue 3
https://doi.org/10.5194/hess-21-1631-2017
https://doi.org/10.5194/hess-21-1631-2017
Research article
 | 
20 Mar 2017
Research article |  | 20 Mar 2017

High-magnitude flooding across Britain since AD 1750

Neil Macdonald and Heather Sangster

Abstract. The last decade has witnessed severe flooding across much of the globe, but have these floods really been exceptional? Globally, relatively few instrumental river flow series extend beyond 50 years, with short records presenting significant challenges in determining flood risk from high-magnitude floods. A perceived increase in extreme floods in recent years has decreased public confidence in conventional flood risk estimates; the results affect society (insurance costs), individuals (personal vulnerability) and companies (e.g. water resource managers). Here, we show how historical records from Britain have improved understanding of high-magnitude floods, by examining past spatial and temporal variability. The findings identify that whilst recent floods are notable, several comparable periods of increased flooding are identifiable historically, with periods of greater frequency (flood-rich periods). Statistically significant relationships between the British flood index, the Atlantic Meridional Oscillation and the North Atlantic Oscillation Index are identified. The use of historical records identifies that the largest floods often transcend single catchments affecting regions and that the current flood-rich period is not unprecedented.

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Short summary
We use historical records to extend current understanding of flood risk, examining past spatial and temporal variability and ask are the perceived high-magnitude flood events witnessed in recent years really unprecedented? We identify that there are statistically significant relationships between the British flood index and climatic drivers, whereby the largest floods often transcend single catchments affecting regions and that the current flood-rich period is not unprecedented.