October was a relatively mild month in the UK but with a notably cold interlude – associated with the persistence of northerly and easterly airflows after the first week. The associated limited precipitation during mid-month is reflected in the October rainfall totals – most regions reported modestly below the 1971-2000 average.Storm clouds gather

This analysis is contained within the latest monthly Hydrological Summary (for October 2010) produced by the National Hydrological Monitoring Programme, operated by the Centre for Ecology & Hydrology in conjunction with the British Geological Survey.

Nonetheless, with the benefit of declining evaporation rates, overall reservoir storage increased through October. For England and Wales as whole, storage is now around 5% above the early November average. There are however substantial regional contrasts: reservoir stocks are healthy throughout much of Wales, Scotland and north-west England but substantially below average in parts of south-west Britain. Many rivers were in spate early in the month and flood alerts were common but October runoff totals were generally well within the normal range; moderate medium term runoff deficiencies can still be recognised in some western and southern catchments.

The Summary states, “The residual impact of the 2010 rainfall deficiency is most evident in the below-average groundwater levels for October (in the southern Chalk particularly) but overall groundwater resources remain typical of the autumn. As is often the case, November rainfall totals will be particularly influential in determining the water resources outlook for 2011.”

The Centre for Ecology & Hydrology jointly operates the National Hydrological Monitoring Programme (NHMP) 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.

Related CEH links

Read the full October 2010 Hydrological Summary for the UK [PDF, 2.21mb]

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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