October was notably dry for most of the UK, with high pressure dominating for most of the month and a good deal of autumn sunshine seen in many regions. The conditions extended appreciable rainfall deficiencies which have developed since July in southern England, and significant soil moisture deficits persisted in many areas.
River flows and groundwater levels generally continued to recede. October river flows were below normal across much of the country and were exceptionally low in some western index catchments. Groundwater levels generally remained in the normal range or moderately below.
The assessment is contained in the latest monthly hydrological summary for the UK, the most authoritative analysis of water resources status in the country. The monthly summaries are produced by the National Hydrological Monitoring Programme, operated by the Centre for Ecology & Hydrology in conjunction with the British Geological Survey.
With depressed autumn runoff, reservoir stocks declined steeply in many impoundments but at the national scale stocks are generally near-average (though 7% below average for Northern Ireland). Stocks were substantially below-average in some areas, particularly in some impoundments in south-west England where stocks have declined steeply since the spring. Clatworthy in west Somerset for example registered 34% below average, its third lowest October stocks after the drought years of 2003 and 1989.
Summary author Jamie Hannaford of the Centre for Ecology & Hydrology said, "Overall the water resources situation is favourable at the national scale. However the delay in commencement of substantial aquifer recharge or reservoir replenishment suggests continuing vigilance will be required through the winter half-year, particularly in areas where current levels or stocks imply recovery will begin from a below-normal baseline. Current seasonal outlooks slightly favour drier rather than wetter conditions for the winter, albeit with a substantial range of possible outcomes."
Above: October 2016 river flows (green in normal range, yellow and orange below normal)
The monthly summary is a look back at hydrological events occurring in October 2016. Latest information on flood warnings is provided by the Environment Agency, Natural Resources Wales and Scottish Environment Protection Agency (flood warnings for Northern Ireland are not available).
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. The UK Monthly Hydrological Summary is normally published on, or before, the tenth working day, of the following month. A Hydrological Outlook for the UK is also available, and is updated monthly. The latest Outlook can be viewed here.