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Summer 2007 Floods: A Very Singular Event

11 March 2008

The Thames Valley - July 2007A new scientific study of the wet summer of 2007 confirms that the floods were a very singular event and does not support the idea that the exceptional river flooding was linked to climate change. This conclusion is contained within a comprehensive hydrological appraisal of the summer 2007 floods carried out by scientists from the Centre for Ecology & Hydrology.

The new report, The summer 2007 floods in England and Wales − a hydrological appraisal, brings together both flood and meteorological data and systematically breaks down the series of events leading to extensive river flooding, which had no close modern parallel for the June-August period across the UK. 

The Thames at Wallingford - July 2007

Lead author, Terry Marsh, comments: “The river floods of summer 2007 were a very singular episode, which does not form part of any clear historical trend or show consistency with currently favoured climate change scenarios.”

Mr Marsh adds: “The exceptional river flooding last summer fuelled speculation that flood risk is increasing due to global warming. Due to the inherent variability of the UK climate, any extreme hydrological event cannot readily be linked directly to climate change.”

The new report recognises that the 2007 flooding was remarkable in its extent and severity and truly outstanding for a summer event. River flows in many areas exceeded the design limits of many flood alleviation schemes. Rainfall amounts and intensities led to urban drainage systems being overwhelmed in a number of areas. This underlines the UK’s continuing vulnerability to climatic extremes, but long-term rainfall and river flow records confirm the exceptional rarity of the hydrological conditions experienced in 2007.

The report complements a recent paper on flood trends in the UK, which was led by Jamie Hannaford at the Centre for Ecology & Hydrology and published in the International Journal of Climatology late in 2007. The paper found that trends over the last 30-40 years can be identified, but that there is little compelling evidence over the long term to suggest that flood magnitude is increasing.

Mr Marsh continues: “Extreme flooding in the UK is historically rare but vulnerability to flooding has increased markedly as a consequence of floodplain development. This is despite increased resilience to flood risk through improved flood alleviation strategies and more sophisticated flood warning capabilities.” 

The new study is an output from the National Hydrological Monitoring Programme (NHMP), operated jointly by the Centre for Ecology & Hydrology and the British Geological Survey.

Additional information

The full 32 page report "The summer 2007 floods in England and Wales − a hydrological appraisal" is available as a pdf download here. The report is in pdf format and forms a relatively large file (11.5MB).

Media Coverage: BBC Online (external); Guardian Online (external); Daily Telegraph (external)

This work was featured on 'Leading Edge' on BBC Radio 4 on 13th March 2008. You can listen to the programme here (external - audio player required).

Press release Summer 2007 Floods: A Very Singular Event - 11th March 2008 (Issued by the Centre for Ecology & Hydrology). Media enquiries about this work should be directed to the Centre for Ecology & Hydrology Press office.

Some of the analyses in the report refers to this new scientific paper published online in the International Journal of Climatology: Jamie Hannaford and Terry J. Marsh (2007) High-flow and flood trends in a network of undisturbed catchments in the UK (p n/a). International Journal of Climatology (external site - subscription may be required).

The new report is an output from the National Hydrological Monitoring Programme (NHMP), operated jointly by the Centre for Ecology & Hydrology and the British Geological Survey. The hydrometric data analysed in this report were provided primarily by the UK hydrometric measuring authorities (the Environment Agency, Scottish Environment Protection Agency and, in the Northern Ireland, the Rivers Agency); a substantial proportion of the meteorological data used was provided by the Met Office. Most of the data is collated within the National River Flow Archive.

The NHMP was set up in 1988 to document hydrological and water resources variability across the UK. The measuring authorities, together with Defra and OFWAT, provide financial support to the NHMP for the production of monthly Hydrological Summaries for the UK. These are available via the Water Watch pages of the CEH website.

 

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