Friday, 14 February 2014

January 2014 overview

Map showing index well groundwater levels for January 2014
Groundwater levels - January 2014
January saw a continuation of the exceptionally wet weather that began in December 2013.  For example, much of central and southern England received over twice the average rainfall for January.

The persistent rainfall has led to significant recharge across the southern Chalk outcrop, with new January maxima established for six Chalk boreholes.  For example, Chilgrove House well has overflowed.  We believe this well has the longest continuous observation of water levels in the UK - the record starts in 1836 - and such artesian conditions have only happened 6 times before.  Groundwater emergence in bournes has also been observed, e.g. the South Winterbourne (Dorset), Aldbourne (Berkshire), Lavant (Hampshire) and Nailbourne (Kent).

Levels are now increasing in the northern and eastern Chalk, which received less rainfall in December, but these are still below average.

Above average levels have been observed in the Permo-Triassic sandstones of the Midlands and north Wales.  In the north-west and south-west these have been exceptionally high, with record monthly levels recorded at Newbridge, Skirwith and Bussels.

In other aquifers, levels were typically above average, with Ampney Crucis (Jurassic limestone) registering exceptional levels.

With rising water levels in the southern Chalk, concerns over sewer surcharging and groundwater flooding heightened through January; flood alerts were widespread across the southern Chalk (from Dorset to Kent, but predominantly in the west), and were also issued for the Lower Greensand in south-west Surrey. The high water levels on the interfluves will gradually feed into the lower parts of catchments over a period of weeks to months, and it is likely groundwater flooding will persist well into the spring. In some of the major river valleys (e.g. the Thames Valley), elevated groundwater levels in superficial sands and gravels are exacerbating current flooding and the risk of future flooding

For more information, see the hydrological summary for January 2014 [PDF].