August was another rather wet and relatively dull month contributing to the wettest summer since 1912. The extreme departures from normal seasonal rainfall patterns during 2012 resulted in soils being close to saturation over wide areas through most of the summer. Correspondingly, many rivers responded rapidly to the August rainfall and moderate floodplain inundations were common; there was also a high incidence of flash flooding. Estimated outflows from England & Wales over the April-August period were twice the long-term average.
The above analysis is contained within the latest monthly hydrological summary (for August 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 abundant late spring and summer runoff ensured that stocks in almost all index reservoirs increased to well above the seasonal average. For early September, aggregated stocks for England & Wales are the highest on record.
With soil moisture deficits since March also more typical of the winter, aquifer replenishment has also been very exceptional and groundwater levels in most index wells and boreholes are within, or above, the normal early autumn range.
Jamie Hannaford, from the NERC Centre for Ecology & Hydrology, said, “The late spring and summer of 2012 have witnessed an extraordinary transformation in the water resource outlook. Dramatic post-drought recoveries have occurred before, most notably following the extreme drought of 1975/76, but sustained recoveries during the late spring and summer are extremely rare.”
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 August 2012 Hydrological Summary for the UK [PDF, 1.87mb]
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