During November the remarkable hydrological transformation since the severe drought conditions of the early spring was reinforced across much of the United Kingdom. Regional variations in rainfall have been large over the last eight months but for Britain as a whole the April-November rainfall is the highest in a series from 1910. The latter half of November was particularly unsettled, punctuated by periods of heavy and sustained frontal rainfall.November 2012 flooding at Wallingford in Oxfordshire. Photo: Heather Lowther (CEH)

The above analysis is contained within the latest monthly hydrological summary (for November 2012) produced by the National Hydrological Monitoring Programme, operated by the NERC Centre for Ecology & Hydrology (CEH) in conjunction with the NERC British Geological Survey.

With catchments close to saturation river flows responded rapidly and floodplain inundations were both frequent and extensive. Runoff from England and Wales was outstanding during the fourth week of November and, although very high concentrations of suspended solids restricted replenishment to some pumped storage reservoirs (e.g. Farmoor), overall reservoir stocks (for England and Wales) for early December were the second highest on record (after 2000). Stocks in the great majority of index reservoirs across the UK are within 10% of capacity.

Following notable flooding in Scotland on 19 November river basins across much of the country were subject to significant floodplain inundations. In England and Wales, there were Flood Alerts in all regions by the 26th when, very exceptionally, nearly 300 Flood Warnings were also in operation. Instances of substantial flooding were common and widely distributed.

Overall, groundwater resources are also exceptionally healthy although pockets of depressed groundwater levels remain in some of the slowest-responding aquifers – particularly in the Midlands.

Terry Marsh from CEH said, “With catchments remaining close to saturation and the contribution of springs and seepages to river flows increasing, there is an enhanced risk of both fluvial and groundwater flooding through the early winter and probably beyond.”

The Centre for Ecology & Hydrology jointly operates the National Hydrological Monitoring Programme in conjunction with the British Geological Survey. NHMP scientists produce the UK Monthly Hydrological Summary which assesses rainfall, river flows, groundwater and reservoir levels. They also operate the National River Flow archive. The NHMP has a remit to analyse major flood and drought events in the UK and analyse long term trends in UK hydrological data. The Programme was set up in 1988 and relies on the active co-operation of measuring authorities throughout the UK.

Additional information

Read the full November 2012 Hydrological Summary for the UK [PDF, 4.86mb]

Hydrological summary archive - dating back to December 1988

Details of the National Hydrological Monitoring Programme

CEH’s Water Science Programme 

Datasets hosted by CEH: National River Flow Archive, National Water Archive and others

Media enquiries related to the Hydrological Summaries should be directed to the CEH Press Office. Our scientists can provide explanation and analysis of historic hydrological patterns, possible future scenarios under climate change and scientific understanding of the current situation. We are not able to comment on immediate operational issues.

If you wish to reproduce figures from the Monthly Hydrological Summary please respect the copyright credits contained within the document.

 

 

 

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