Thursday, 16 February 2012

Dealing with 'drought' questions

'Drought' questions have been flooding(!) in to CEH this week as several organisations release new data on the UK water situation. Several papers have been having a field day with their headlines. Our favourite was '2011 was the driest year in England and Wales for 90 years' (actually the rainfall records indicate that 2010 was drier than 2011).

Whilst we've been speaking to many journalists on the phone it also seems appropriate to post a selection of useful links giving background on the current situation, and some of the context behind the headlines.

First here is our standard answer to 'What is a drought?' - the simple answer being "droughts mean different things to different people"

Second we run the National Hydrological Monitoring Programme* (more details below). This recent blog post gives more background on what we do with hydrological data (which is rather different to the roles played by other organisations such as the Environment Agency and the Met Office).

We have also just published our latest monthly hydrological summary for the UK, covering the month of January 2012.

The introduction to the summary starts:
“The synoptic patterns which have produced a remarkably sustained exaggeration in the NW-SE rainfall gradient across the UK continued in January. Much of central, eastern and southern England was again relatively dry and the development of the current regional drought now extends across three winter periods with a range of impacts embracing water resources, agriculture and the aquatic environment.” ...and continues... “In the absence of an unusually wet late winter and early spring (as happened in 2000 for example), it is now virtually inevitable that a significant degree of drought stress will be experienced (in some parts of England) in 2012. The magnitude of that stress, and its spatial extent, will be heavily influenced by rainfall over the next 8-10 weeks.”

Key information from the summary can be read here.

A pdf copy of the full 12-page summary can be downloaded from this link.

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

And finally please call us if you have queries. We'll try and help!

Update - 18:30 16 February 2012

A number of news outlets are reporting that "This week the Centre for Hydrology and Ecology reported that average rainfall so far this winter was the lowest since 1972." We're not aware that any of our staff have stated this to journalists and believe it may be a misinterpretation of the following paragraph in the January Hydrological Summary (rainfall section, page 1).

"Accumulated rainfall deficiencies, although locally variable, are exceptional across a wide range of durations. Provisionally, the Anglian region recorded its lowest March-January rainfall in a series from 1910 (over the same 11-month period Scotland established a new maximum precipitation total). As notably, some parts of the Midlands have reported only three months with above average rainfall since November 2009 and the accumulation for the subsequent 26 months is the lowest on record (for periods beginning in December) in a series from 1910; for the Thames basin it was the driest since 1972-74 – such deficiencies were more common in the 19th century."

The National Hydrological Monitoring Programme

*The Centre for Ecology & Hydrology jointly operates the National Hydrological Monitoring Programme (for the UK) 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 UK’s National River Flow archive. The NHMP also has a remit to analyse major flood and drought events in the UK and analyse long term trends in UK hydrological data.

Posted by Barnaby Smith

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