Friday, 18 July 2014

Groundwater outlook - from July 2014

Hydrological Outlook from July 2014
At this time of year, significant groundwater recharge is unlikely and groundwater levels are not strongly influenced by variations in rainfall.  Levels are expected to fall during the next three months along a similar trajectory to recent months.  There is unlikely to be any significant change to the groundwater situation until October, when water use by plants reduces and rainfall will begin to dictate the groundwater outlook.

View or download the most recent Hydrological Outlook from the Hydrological Outlook UK website.

Wednesday, 16 July 2014

June 2014 overview

Groundwater levels, June 2014
Groundwater levels normally fall in the summer months.  Recharge is limited as most of the rain that falls is captured by dry soils and used by growing plants. Groundwater drains naturally from aquifers towards rivers
and the sea.  During these months, there is more water leaving the aquifers than replenishing them, so we see water levels fall.  This falling section of a groundwater hydrograph is called the recession.

Hydrographs in most wells are showing the summer recession.  For example, in the Chalk aquifer at Little Bucket Farm, and in the Permo-Triassic Sandstones at Bussels No. 7a.
Falling groundwater levels in the Chalk at Little Bucket Farm (Kent)

Heavy rainfall in some areas in May was enough to interrupt the recession, so we see the hydrograph curving upwards, e.g. in the Lincolnshire Limestone at New Red Lion.
Interrupted recession in the Lincolnshire Limestone
at New Red Lion (east of Grantham, Lincolnshire)

Levels in some areas remain exceptionally high for the time of year, due to the exceptional spring rainfall, even though they are falling.  This is the case in the Permo-Triassic Sandstone aquifers of the north west (e.g. Skirwith) and the south west (e.g. Bussels No. 7a).

For more information, see the Hydrological Summary for June 2014 [PDF].

Wednesday, 2 July 2014

May 2014 overview

Groundwater levels, May 2014
The weather in May was changeable, and the total rainfall varied significantly across the UK.  We saw heavy rainfall at the end of May, which caused unusually low soil moisture deficits in most areas. Despite the generally high rainfall, groundwater levels mostly continued to fall.

Chalk water levels generally fell during May but remained within the normal range or above, with exceptionally high levels at Stonor Park (Chilterns). However, in Yorkshire levels remained below average, even though the monthly rainfall total over the chalk of Yorkshire was mostly >175% of the average for May.  Local rises in levels were recorded in parts of Lincolnshire and Suffolk.

In the Permo-Triassic sandstones, despite falls, water  levels remained above previous monthly maxima in the north-west (for the fifth consecutive month) and were also very high in the south-west. Levels elsewhere were above average and rose in north Wales.

In the Upper Greensand of south-west England, at Lime Kiln Way, levels fell slightly 
but remained above the previous monthly maximum for the fourth consecutive month. 

In the Magnesian Limestone, water levels in the indicator boreholes were notably high in the north. In the other limestone aquifers, levels returned to the normal range, except at Pant y Lladron where they were exceptionally high with a rise of 5m recorded across the 24th-25th May in response to rainfall