February was a further month when synoptic patterns greatly restricted the passage of Atlantic frontal systems across most of southern and eastern Britain. Correspondingly, drought conditions intensified at a critical time in relation to the water resources outlook.
The above analysis is contained within the latest monthly hydrological summary (for February 2012) produced by the National Hydrological Monitoring Programme, operated by the Centre for Ecology & Hydrology in conjunction with the British Geological Survey.
Terry Marsh, from the Centre for Ecology & Hydrology (CEH), said, “Rainfall in early March was very welcome but in the absence of truly exceptional rainfall, in excess of 150% of average, over the next 6-8 weeks (by which time evaporation demands will be rising rapidly) no early termination to the drought can be expected.”
Across Wales, northern Britain and Northern Ireland, stocks in major reservoirs are generally within 10% of capacity; this is true also of the major pumped storage impoundments in the Thames basin. By contrast, stocks are below average in parts of the South West, East Anglia and, most notably the South East where Ardingly and Bewl Water reported their lowest early-March stocks in a series from 1988.
Soils for the late winter were the driest on record in some central and eastern areas. This is a continuing problem for the farming community but, after two successive dry winters, the drought is also impacting severely on the environment and water resources.
Some wetlands are highly stressed (e.g. Titchwell Marsh in Norfolk), movement restrictions apply on some canals (e.g. the Grand Union) and the failure of springs has contributed to an exceptional contraction in the river network.
River flows in much of the drought-affected areas are below those normally expected in the late summer and in some rivers late-winter flows were below the corresponding flows during the extreme drought of 1975/76. The depressed flows are associated with low oxygen levels and limited dilution for sewage effluent, necessitating a number of fish rescues – a contingency normally associated with the late summer and early autumn. Groundwater recharge over the winter has been meagre across many of the major aquifer outcrop areas and February groundwater levels were close to the lowest on record over wide areas
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.
Read the full February 2012 Hydrological Summary for the UK [PDF, 2.37mb].
Hydrological summary archive - dating back to March 1997 [NEED NEW INTERNAL LINK]
Details of the National Hydrological Monitoring Programme [NEED NEW INTERNAL LINK]
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.
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