A hydrological assessment of the November 2009 floods in Cumbria, UK

• Published in: Hydrology Research Vol. 44; no. 1; pp. 180 - 197
• Main Authors: MILLER, J. D, KJELDSEN, T. R, HANNAFORD, J, MORRIS, D. G
• Format: Journal Article
• Language: English
• Published: London International Water Association 01.01.2013; IWA Publishing
• Subjects: Assessments; Catchment area; Catchments; Discharge measurement; Downstream effects; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Estimates; Exact sciences and technology; Flood estimation; Flood frequency; Flooding; Floods; Frequency analysis; Frequency estimation; Freshwater; Gaging stations; Hydrology; Hydrology. Hydrogeology; Lake levels; Lakes; Natural hazards: prediction, damages, etc; Procedures; Rain; Rainfall; Reviews; River discharge; River flow; Rivers; Stream discharge; Uncertainty analysis; England; United Kingdom; Great Britain; Cumbria England; Europe; Western Europe; United Kingdom > UK; rivers; floods; rainfall; atmospheric precipitation; inundations; frequency; November 2009; drainage basins; flood frequency; Cumbria; return period; prediction; lakes; uncertainties; flow; gauging
• ISSN: 1998-9563; 0029-1277; 2224-7955
• DOI: 10.2166/nh.2012.076

In November 2009, record-breaking rainfall resulted in severe, damaging flooding in Cumbria, in the north-west of England. This paper presents an analysis of the river flows and lake levels experienced during the event. Comparison with previous maxima shows the exceptional nature of this event, with new maximum flows being established at 17 river flow gauging stations, particularly on catchments influenced by lakes. The return periods of the flood peaks are estimated using the latest Flood Estimation Handbook statistical procedures. Results demonstrate that the event has had a considerable impact on estimates of flood frequency and associated uncertainty. Analysis of lake levels suggests that their record high levels reduced their attenuating effect, significantly affecting the timing and magnitude of downstream peaks. The peak flow estimate of 700 m3s-1 at Workington, the lowest station on the Derwent, was examined in the context of upstream inputs and was found to be plausible. The results of this study have important implications for the future development of flood frequency estimation methods for the UK. It is recommended that further research is undertaken on the role of abnormally elevated lake levels and that flood frequency estimation procedures in lake-influenced catchments are reviewed.