Wednesday, 22 April 2015

March 2015 overview

Groundwater levels, March 2015

With dry conditions prevailing across southern and eastern England during March, soil moisture deficits (SMDs) began to develop across the Chalk outcrop. Groundwater levels in index boreholes generally fell in March and, with a few exceptions, were in the normal range or just below for the time of year.

Levels in the Chalk receded in most areas and were below average for the time of year in the Yorkshire Wolds and at Tilshead in Wiltshire. However, modest rises (less than 1 m) were recorded in parts of the Chilterns (Stonor Park and Therfield Rectory), Norfolk (Washpit Farm) and Lincolnshire (Aylesby). In the North Downs, Well House Inn has risen but remains normal, whereas Little Bucket Farm remains notably high despite a fall in water level. Levels in the South Downs were slightly above normal, reflecting higher late-winter rainfall in the far south-east of England.

Groundwater level at Wetwang, Chalk of Yorkshire
In the faster responding Jurassic and Magnesian limestones of central England, levels fell and were average or below. In the Permo-Triassic sandstones, levels were relatively stable, remaining exceptionally high at Nuttalls Farm in the Midlands and at Newbridge in south-west Scotland. Levels at Lime Kiln Way in the Upper Greensand of south-west England fell and remain in the normal range, while in the Lower Greensand of south-east England, levels remain high despite falling. In the flashy Carboniferous Limestone, levels fell and are normal in south Wales and below normal at Alstonfield (Derbyshire).

As SMDs increase throughout the spring and summer, significant recharge is unlikely unless exceptional rainfall is received, with levels likely to continue their normal seasonal recessions from now until the autumn.

For more information, see the Hydrological Summary for March 2015 [PDF].

Thursday, 16 April 2015

Hydrological Outlook from April 2015

Hydrological outlook map The latest Hydrological Outlook is available!

In March, normal groundwater levels were widespread across the Chalk, but with below-normal levels in north-east England and above-normal levels in the far south-east. Levels were variable in other aquifers, with both above- and below-normal levels in the Permo-Triassic of central England. 


With recessions established in most aquifers, groundwater levels over one to three months are relatively insensitive to  rainfall, with significant recharge unlikely unless rainfall is exceptional. 


The one month outlook suggests significant areas of the Chalk aquifer will see below normal levels and, except in the far south-east, the three month outlook suggests a predominance of below normal levels, with an increased probability of some notably low levels by mid-summer. Levels in the Permo-Triassic of northern England and southern Scotland are likely to remain normal or above.


For further information see the full Hydrological Outlook for August.