Tuesday, 19 August 2014

July 2014 overview

Groundwater levels, July 2014
July was a pleasant summer month over most of the UK.  The rainfall total was slightly below average, but the distribution varied significantly.  Thunderstorms brought downpours to areas of the Midlands, the south-east and East Anglia.  Wales and parts of England were notably dry.

Groundwater levels in the very responsive Carboniferous Limestone aquifer of south Wales fell as a result of the low rainfall there.  This is the only site with below normal groundwater levels on our map this month.

Across the rest of the UK, groundwater levels are in the normal or above normal range for the time of year.  Levels are falling at the moment as we are in the recession phase of the annual cycle of groundwater fluctuations.

Below is the hydrograph for Wetwang, a 46 m deep borehole used to measure groundwater level in the Chalk aquifer in Yorkshire.  The dashed line shows the average groundwater level by month.  The observed level (solid black line) indicates the low levels at the start of the year, followed by a rapid recovery during the wet months of January and February.  The steepest section of the recovery shows almost 10 m rise in water level in a little over a month.  The recession, which started in late February, was initially steep, followed by a period of rather stable level during May and June.  During July the groundwater level at Wetwang has closely followed the monthly average line.  Groundwater levels are expected to continue to fall until the autumn.

Groundwater levels at Wetwang, unconfined Chalk

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