The wettest April in the last 100 years, and the coldest since 1989, served to greatly moderate drought conditions in parts of the UK, with the focus of short-term hydrological concern switching rapidly from drought stress to flood risk. This brought associated problems, including the ecological impact of wetland inundations.Photo: Raindrops on the webcam at CEH's River Lambourn observatory

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

After March saw the lowest recorded rainfall for the UK since 1953, the April rain was useful for farmers and growers. But with shallow soils saturated, runoff rates increased dramatically in many areas. Localised flash flooding was reported in many areas, and more than 100 flood warnings were in operation for rivers across England and Wales by the final week of the month.

Terry Marsh, from the Centre for Ecology and Hydrology said, "The decline in soil moisture deficits through April was remarkable, allowing groundwater recharge to re-commence during the latter half of the month. Early indications suggest that the seasonally late pulse of recharge will, in many areas, ensure that groundwater levels remain above historical minima through the summer and, given normal rainfall patterns, provide a foundation for a sustained groundwater recovery through the late autumn and winter.

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.

Additional information

Read the full April 2012 Hydrological Summary for the UK [PDF, 1.79MB]

Hydrological summary archive - dating back to March 1997

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

Dealing with 'drought' questions - a blog post from CEH Science News

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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