Reassessing flood frequency for the Sussex Ouse, Lewes: the inclusion of historical flood information since AD1650

Macdonald, N ORCID: 0000-0003-0350-7096, Kjeldsen, TR, Prosdocimi, I and Sangster, H ORCID: 0000-0001-6024-9041 (2014) Reassessing flood frequency for the Sussex Ouse, Lewes: the inclusion of historical flood information since AD1650 NATURAL HAZARDS AND EARTH SYSTEM SCIENCES, 14 (10). pp. 2817-2828. ISSN 1561-8633, 1684-9981

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Abstract

The application of historical flood information as a tool for augmenting instrumental flood data is increasingly recognised as a valuable tool. Most previous studies have focused on large catchments with historic settlements, this paper applies the approach to the smaller lowland system of the Sussex Ouse in southeast England. The reassessment of flood risk on the Sussex Ouse is pertinent in light of the severe flooding in October 2000 and heightened concerns of a perceived increase in flooding nationally. Systematic flood level readings from 1960 and accounts detailing past flood events within the catchment are compiled back to ca. 1750. This extended flood record provides an opportunity to reassess estimates of flood frequency over a timescale not normally possible within flood frequency analysis. This paper re-evaluates flood frequency at Lewes on the Sussex Ouse downstream of the confluence of the Sussex Ouse and River Uck. The paper considers the strengths and weaknesses in estimates resulting from contrasting methods of analysis and their corresponding data: (i) single site analysis of gauged annual maxima; (ii) combined analysis of systematic annual maxima augmented with historical peaks of estimated magnitude; (iii) combined analysis of systematic annual maxima augmented with historical peaks of estimated magnitude exceeding a known threshold, and (iv) sensitivity analysis including only the very largest historical flood events. Use of the historical information was found to yield much tighter confidence intervals of risk estimates, with uncertainty reduced by up to 40% for the 100-year return frequency event when historical information was added to the gauged data.

Item Type:	Article
Uncontrolled Keywords:	3707 Hydrology, 3709 Physical Geography and Environmental Geoscience, 3701 Atmospheric Sciences, 37 Earth Sciences
Depositing User:	Symplectic Admin
Date Deposited:	11 Apr 2016 12:05
Last Modified:	22 May 2026 23:35
DOI:	10.5194/nhess-14-2817-2014
Open Access URL:	http://www.nat-hazards-earth-syst-sci.net/14/2817/...
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3000193
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