The persistent and seasonally unusual southerly track of the jet stream contributed to June weather conditions more typical of the late autumn. Record June rainfall totals were recorded in many areas and the normal seasonal decline in runoff and aquifer recharge rates, which began in April, was dramatically accentuated.
The above analysis is contained within the latest monthly hydrological summary (for June 2012) produced by the National Hydrological Monitoring Programme, operated by the NERC Centre for Ecology & Hydrology in conjunction with the NERC British Geological Survey.
The record April-June rainfall resulted in an almost complete termination of drought conditions (north-west Scotland aside) and, very unusually for the summer, the focus of hydrological concern switched decisively to the risk of flooding. Flood warnings, relating to both fluvial and flash flood risk, were common and widespread. The exceptional runoff rates impacted severely on property, transport, agriculture and leisure activities but the post-March runoff has also transformed the water resources outlook. Stocks in almost all index reservoirs are close to, or above, the normal early July level.
Terry Marsh, from the NERC Centre for Ecology & Hydrology (CEH), said, "The remarkable temporal contrast in rainfall amounts over the last ten months has caused an unprecedented shift in the aquifer recharge season."
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 June 2012 Hydrological Summary for the UK [PDF, 1.82MB]
Details of the National Hydrological Monitoring Programme
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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