On the water front – groundwater matters at the BGS

January 2016 overview

2016-02-17T14:05:00.004+00:00

Groundwater levels, January 2016

January was very wet (the 4th wettest January since 1910), with all regions registering above average rainfall. Over double the average rainfall was recorded in north-eastern areas and along the south coast.

The saturated soils throughout the UK meant groundwater levels responded to recharge in all aquifers. Levels were in the normal range or above, apart from two slowly responding sites in the Chalk of central and eastern England. At fast responding sites, the rapid rise in levels that commenced in December continued into January.

Levels in many aquifers fell mid-month, but generally rose again by month-end (e.g. in the Chalk of the South Downs, parts of the Cotswolds limestones, most of the Permo-Triassic sandstones and the Carboniferous Limestone of south Wales). At month-end, water levels in the Chalk were notably or exceptionally high (at Wetwang and along the south coast) where levels responded rapidly to the exceptional rainfall, or in the normal range and rising at slowly responding sites. However, groundwater flooding in the south-east of England was localised and minor, with a few flooded cellars and surcharged sewers.

Hydrograph from Chilgrove, showing

groundwater levels in the unconfined Chalk

The hydrograph from Chilgrove (West Sussex) in the unconfined Chalk aquifer of the South Downs shows a groundwater level of about 74 mAOD at the end of January, some 17 m above the average level for that time of year. The multiple peaks are typical of this observation well: levels rise after periods of prolonged of heavy rainfall but decline during drier periods. This is typical of a responsive part of the Chalk aquifer.

Groundwater level at Newbridge, near Dumfries,
in the Permo-Triassic sandstone

Levels in the Permo-Triassic sandstones were generally in the normal range, with the exception of north-west England and south-west Scotland where they were higher due to the exceptional rainfall over the last three months; a record monthly level was again recorded at Newbridge.

Levels rose in the Magnesian Limestone index boreholes, with a record maximum January level recorded at Brick House Farm.

For more information, see the Hydrological Summary for January 2016.

Hydrological Outlook from February 2016

2016-02-17T10:20:00.001+00:00

The latest Hydrological Outlook is available.

Hydrological Outlook from February 2016

The rainfall received during December and January brought groundwater levels into, or above, their normal range across most aquifers.

Groundwater levels in the rapidly responding Chalk aquifers along the south coast rose quickly, and are likely to stay notably high over the next one to three months.

In other parts of the Chalk levels will generally be normal or above normal; where they are currently below normal in some aquifers in central and eastern England the trend is for rising levels. In Yorkshire drier conditions in January have slowed the rate of increase seen since December, but levels should remain above normal over the next three months.

The Permo-Triassic sandstone aquifers in northern Britain characteristically respond slowly, and this means that the exceptionally high levels recorded in these aquifers will be likely to persist over the next three to six months.

For further information see the full Hydrological Outlook for February.

December 2015 overview

2016-01-19T14:43:00.001+00:00

Groundwater levels, December 2015

The UK saw widespread and severe fluvial flooding in December, as exceptional rainfall led to some very high river flows.

Levels in the index boreholes were generally in the normal range or above for December. Levels recovered in response to winter recharge, except at some sites in parts of the eastern Chalk with thick unsaturated zones or where recharge was limited by superficial deposits (Aylesby, Therfield Rectory, Stonor Park, Well House Inn and Westdean No. 3)
and at Nuttalls Farm (in the Permo-Triassic sandstone).

Groundwater level at Newbridge, near Dumfries

The exceptional rainfall in the northern half of the UK resulted in high groundwater levels with record monthly values recorded at Killyglen (Chalk) and Newbridge (Permo‑Triassic sandstone). The groundwater level for Newbridge, near Dumfries, was the highest December value since records began in 1993.

Other levels in the north were notably high, except for Dalton Holme, which normally
responds slowly to recharge from rainfall. Groundwater from the Corallian aquifers at Old Malton in North Yorkshire contributed to high river levels, and high groundwater levels in permeable superficial deposits contributed to flooding in river valleys across northern Britain.

For more information, see the Hydrological Summary for December 2015.

Hydrological Outlook from January 2016

2016-01-13T16:28:00.001+00:00

The latest Hydrological Outlook is available.

Hydrological Outlook from January 2016

December groundwater levels in the Chalk displayed a very mixed pattern, with below normal levels in some boreholes in central southern England and normal or above normal levels elsewhere.

In other aquifers levels were normal or above normal, with very high levels in some northern aquifers. For example, the groundwater level at Newbridge near Dumfries is exceptionally high (see hydrograph below).

Based on early January rainfall, groundwater levels in the next month are likely to be normal or above except in the slower responding parts of the Chalk in central and eastern England.

Hydrograph from Newbridge, showing
groundwater levels in Permo-Triassic Sandstone

Exceptionally high levels will persist across Permo-Triassic aquifers in the north. In the Yorkshire Chalk and in Wessex and along the south coast, levels may rise to notable or exceptional levels and this may result in localised groundwater flooding.

The three month outlook suggests a similar pattern, with normal to above normal groundwater levels prevailing, and a significant chance of notably high or exceptionally high levels in the most responsive aquifers.

For further information see the full Hydrological Outlook for January.

Groundwater and the recent floods

2016-01-07T14:16:00.002+00:00

The flooding that has occurred in Northern England and Scotland in the past month has primarily involved surface water, so we didn't think there would be a great interest in our thoughts on it. However, the web logs for the BGS website showed that many people had been searching for information on the floods. Yesterday we put up a web page which answers the question:
Has groundwater influenced the recent UK floods (December 2015 — January 2016)?

If you've got any questions then we'll be happy to try and answer them. Join the conversation on our Twitter feed: @BGSGroundwater

October 2015 overview

2015-11-18T16:58:00.000+00:00

End of October soil moisture deficits were lower than average in the south of England

Groundwater levels, October 2015

reflecting the late summer rainfall, but above average in central and eastern England.

Groundwater levels remained stable or continued their seasonal recession in the majority of index boreholes.

However, in the Chalk of south Dorset and the western South Downs levels at Ashton Farm, Compton House, West Woodyates Manor and Chilgrove House continued to rise (the last two by three metres) in response to recent recharge. Levels at Compton House and Chilgrove House rose to the normal range, whilst levels at Ashton Farm remained notably high. Elsewhere, levels fell in October and were generally average or slightly below at month-end, with the exception of Tilshead, Well House Inn, Dalton Holme and Wetwang which were notably low and Little Bucket Farm which rose to above normal.

In the Jurassic and Magnesian limestones, levels fell or stabilised and were in the normal range. In the slower responding Permo-Triassic sandstones levels fell, returning to the normal range after four months of record high levels at Newbridge. Levels were average or above, with the exception of Llanfair DC which is notably low.

Levels in the rapidly responding Carboniferous Limestone boreholes of south Wales and the Peak District fell and were all below normal. Levels at Greenfield Garage fell from notably high at the end of September to below normal.

For more information, see the Hydrological Summary for October 2015.

Hydrological Outlook from November 2015

2015-11-18T16:52:00.000+00:00

The latest Hydrological Outlook is available.

Hydrological Outlook from November 2015

In the Chalk, levels in October were mostly normal or below. Notably low levels persisted in north-east England, while southern England saw a mixed pattern with some notably low levels in more central areas contrasting with above normal levels in parts of the far south. Levels in other aquifers were also mostly normal or below.

The one month outlook indicates a similar pattern. For the three month outlook, below-normal levels are far less prevalent, with normal levels predominant across all aquifers and above normal levels possible in some localised areas. The shift towards normal levels again reflects the precipitation forecasts but, as with river flows, projections are highly uncertain.

Groundwater projections are particularly uncertain at this transitional time of year; late autumn and early winter rainfall will be highly influential on the longer-term outlook.

September 2015 overview

2015-10-15T14:09:00.000+01:00

Groundwater levels, September 2015

September was a dry month, with less than half of the long-term average rainfall. The west of Scotland was particularly dry, but only south eastern England had close to or slightly above average rainfall.

Soil moisture deficits remained similar to those at the end of August for most regions in England and Wales, but were closer to average. Consequently, the majority of the index boreholes continued their seasonal recessions in September.

In the Chalk, levels were average or below, except at Ashton Farm where they were notably high following an increase in September. Increases were also observed at West Woodyates Manor, Compton House and Chilgrove House (all in Dorset or the western South Downs).

Levels in the Jurassic limestones were similar to, or below, those recorded recorded at the end of August. In the Magnesian Limestone, levels fell but remained in the normal range.

Groundwater levels at Alstonefield (Carboniferous Limestone)

In the slower responding Permo Triassic sandstones, levels fell at all of the index boreholes. With the exceptions of Llanfair DC and Skirwith, levels were normal or above. A new period of record month-end maximum level was recorded at Newbridge (for the fourth consecutive month) and levels remained notably high at Nuttalls Farm.

In the fast responding Carboniferous Limestone, levels fell and remained in the normal range at Alstonefield. In south Wales, levels rose at Greenfield Garage and fell at Pant y Lladron, but levels remained above normal in both boreholes.

For more information, see the Hydrological Summary for September 2015.

Hydrological Outlook from October 2015

2015-10-15T13:35:00.001+01:00

The latest Hydrological Outlook is available.

Hydrological Outlook from October 2015

Following a dry September, the probability that UK precipitation for October-November-December will fall into the driest of five equal categories is 15% and the probability that it will fall into the wettest of five equal categories is 35%.

Across the chalk aquifer, levels in September were below normal in central southern England and in much of eastern England, and normal elsewhere.

Levels in other aquifers were mixed, mostly normal to below except for above normal levels in parts of the Permo-Triassic sandstone and Carboniferous limestone.

Groundwater levels are expected to be normal to below normal over the next month, but with above normal levels occurring in parts of the southern Chalk, mainly in response to the August rainfall. Over the next three months, normal levels predominate, but the outlook is much more uncertain as this is the period where winter recharge typically starts; entering the recharge season with broadly normal groundwater levels, the outlook is highly sensitive to late autumn rainfall.

For further information see the full Hydrological Outlook for October.

August 2015 overview

2015-09-23T17:59:00.000+01:00

Groundwater levels, August 2015

August was wetter than average for the UK (133% of the long-term average rainfall), bring a rather damp summer to a close (126% of average rainfall for the UK for June-August). The south coast of England had particularly high rainfall in August, with over twice average rainfall falling over large areas, and nearly three times in some places.

The focus of the wet weather in August across southern England significantly reduced soil moisture deficits in this area, and caused temporary interruptions in seasonal recessions for some boreholes.

The majority of the index boreholes were within or close to the normal range. In the Chalk, levels generally were near or below average, although Killyglen was above normal and Westdean No.3 was exceptionally high. Seasonal recessions were temporarily halted in localised areas of southern England (Ashton Farm, West Woodyates Manor, Tilshead and Houndean Bottom) by the late August rainfall, although the recessions may have since continued.

Levels in the Jurassic limestones fell during August and were also normal or just below; recessions were again briefly halted. In the Magnesian limestone, although levels generally were in the normal range, they fell at Swan House and rose slightly at Brick House Farm. In the slowly responding Permo-Triassic sandstones, with the exception of Llanfair DC, levels were near or above average, with record high August levels recorded at Newbridge (for the third month in succession) and also notably high levels at Nuttalls Farm (although lower than the exceptionally high levels in July). In the fast responding Carboniferous Limestone, levels fell but remained in the normal range in the Peak District, and rose in south Wales to be above normal, reflecting differences in regional rainfall.

For more information, see the Hydrological Summary for August 2015.

Hydrological Outlook from September 2015

2015-09-23T17:43:00.001+01:00

The latest Hydrological Outlook is available.

Hydrological Outlook from September 2015

The forecast for precipitation over September-October-November as a whole is indistinguishable from climatology.

Groundwater levels in August exhibited a very similar pattern to recent months: below normal levels in parts of the southern and eastern Chalk contrasted with normal levels elsewhere in the aquifer.

Levels in other aquifers were mostly normal, with above normal levels in some western aquifers, and variability in the Permo-Triassic boreholes where exceptionally high levels persist in Scotland.

The one month outlook indicates a broadly similar pattern but suggests that levels in the southwestern chalk will return to normal. The three month outlook suggests this may be a shortlived effect, and a more mixed picture of normal to below-normal levels emerges across the southern Chalk. However, below normal levels in the north-east Chalk are likely to persist. Levels in other aquifers are likely to be normal or below-normal, with above-normal levels in parts of the Permo-Triassic sandstone.

For further information see the full Hydrological Outlook for September.

July 2015 overview

2015-08-18T16:18:00.003+01:00

Groundwater levels, July 2015

July was wet: the majority of UK regions registered in excess of 150% of the long-term average rainfall. Parts of north-east and south-west England, and particularly much of Scotland and East Anglia, recorded more than 200% of average rainfall, whilst near or below average rainfall was restricted to areas of Kent and Sussex, the Midlands and the far north of Scotland.

Soil moisture deficits decreased throughout the UK in July, but despite this, levels continued to fall at all index sites except Killyglen, Pant y Lladron and Dial Farm. However, in some places recession rates slowed due to heavy rainfall in the last week of the month.

With the exception of the fast responding Chalk at Killyglen, levels in the Chalk were near average or below, with notably low levels which persisted since the end of June at Tilshead and Dalton Holme. Levels decreased in July at Chilgrove House and Compton House and were notably low by month-end.

Groundwater levels at Ampney Crucis in the Jurassic limestones

In the Jurassic limestones, levels fell and remained in the normal range or below, and in the Magnesian Limestone, levels remained in the normal range at Brick House Farm.

In the Permo-Triassic sandstones, levels were near to above average, except for Llanfair DC where levels were below normal. For the second consecutive month, Newbridge recorded a new monthly maximum level. Levels at Nuttalls Farm were also exceptionally high and registered as the third highest end of July level in record from 1974. Levels in the fast responding Carboniferous Limestone of south Wales were near to above normal.

For more information, see the Hydrological Summary for July 2015.

Hydrological Outlook from August 2015

2015-08-12T10:20:00.004+01:00

Hydrological Outlook from August 2015

The latest Hydrological Outlook is available.

The latest predictions for UK precipitation favour below-average rainfall for August and August-September-October as a whole.

In southern and eastern England, July groundwater levels were normal to below normal, notably so in parts of the Chalk in Hampshire, Wiltshire and Yorkshire.

Conversely, levels were exceptionally high in parts of the slowly responding Permo-Triassic sandstones of the Midlands and southern Scotland.

The outlook for August is for the continuation of a similar pattern. Below normal levels are likely in Wessex, Wales and eastern England, whilst above normal levels are likely to persist in parts of the Permo-Triassic aquifers.

The outlook for the next three months is also similar, with exceptionally low levels possible in parts of the southern Chalk.

For further information see the full Hydrological Outlook for August.

June 2015 overview

2015-07-15T15:05:00.003+01:00

Groundwater levels, June 2015

Overall, June was dry, especially in parts of south-east England, and sunnier than average. With dry conditions over the main outcrop areas, particularly in the far south-east, and some notably warm spells later in the month, by the end of the month soil moisture deficits (SMDs) climbed to well above the average for late June. Correspondingly, groundwater levels in all indicator wells fell during June as would be expected at this time of year, when any rainfall is likely to be lost as evapotranspiration.

In the Chalk the pattern established in recent months continued. Levels were above normal for the time of year at Little Bucket Farm (Kent), but generally levels were normal or below, with below normal levels in western parts of the aquifer (Wessex and western parts of the South Downs) and parts of East Anglia and Yorkshire. Ashton Farm in Wessex recorded its fifth lowest June average level in a 42 year record.

In the Magnesian and Jurassic limestone aquifers levels were either normal or below, and levels in the Carboniferous Limestone of South Wales and Derbyshire remained in the normal range.

Groundwater levels at Newbridge in the Permo-Triassic Sandstones

In the Permo-Triassic sandstones, levels were average or well above; Nuttalls Farm in the West Midlands saw exceptionally high levels while Newbridge (south west Scotland) reached a record high for June (see hydrograph). These aquifers respond slowly to changes in rainfall, and the latter is located in an area that has seen moderately above-average rainfall over recent months.

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

Hydrological Outlook from July 2015

2015-07-14T16:38:00.000+01:00

The latest Hydrological Outlook is available.

Hydrological Outlook for July 2015

The latest predictions for UK precipitation favour near- or below-average rainfall during July and for July-August-September as a whole.

Groundwater levels in June exhibited a very similar pattern to recent months: below normal levels in parts of the southern and eastern Chalk contrasted with normal levels elsewhere in the aquifer. Levels in other aquifers were mostly normal or below, except in some Permo-Triassic boreholes where exceptionally high levels persist.

This pattern is likely to continue through July, with recessions largely unaffected by summer rainfall. Over the three month timeframe (Jul-Sep), model projections suggest that groundwater levels in some areas with below normal levels may be trending towards the normal range. However, analysis of historical analogues suggests that this may be unrealistic and that below normal levels in Wessex and the Yorkshire Chalk are likely to persist into early autumn. The onset of the recharge season is likely to be delayed in areas in which below normal levels persist in the longer term.

For further information see the full Hydrological Outlook for July.

May 2015 overview

2015-06-24T14:44:00.001+01:00

Recessions in groundwater levels continued during May, despite the wet conditions over much of the UK. Soil moisture deficits (SMDs) have become established in south-eastern areas, meaning rainfall is taken up by the soil rather than recharging aquifers.

Groundwater levels, May 2015

Across most Chalk aquifers, levels remained normal although they declined at a slightly faster rate than is typical. In Yorkshire, Wetwang and Dalton Holme were notably low. Compared to April, more of the Wessex and Hampshire Chalk was below normal; notably low levels were recorded at Ashton Farm and Tilshead, which recorded its sixth lowest May level in 47 years. Only two Chalk boreholes (Therfield Rectory and Little Bucket Farm) recorded above normal levels – these boreholes continued to be influenced by the wet conditions of 2013/14.

Elsewhere the situation was mixed. In south-west England and south Wales, levels remained normal. Levels in the Jurassic limestone were below normal in southern areas and nearer normal further north. Swan House, in the Magnesian Limestone, was an exception, recording below normal levels due to limited recharge this winter.

Several Permo-Triassic boreholes remained at exceptionally high levels, the legacy of exceptional recharge in 2013/14, whilst others were close to their seasonal norms. An exception was Llanfair D.C. in north Wales, where levels were slightly below normal.

Any moderation of recessions in the Chalk from a wet May was yet to show at month-end. Low levels in Wessex and Hampshire may persist through the summer or decline further, though still well above the minima of 2011/12.

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

Hydrological Outlook from June 2015

2015-06-16T17:40:00.001+01:00

The latest Hydrological Outlook is available.

In the Chalk, May groundwater levels were mainly normal in the south-east, but levels were below normal (and notably low in some boreholes) in parts of southern England and Yorkshire.

Levels were mixed in other aquifers, with exceptionally high levels persisting in parts of the Permo-Triassic sandstone.

The one month outlook suggests a similar situation will continue in June, although levels in the Permo-Triassic are likely to be notably high rather than exceptional.

The groundwater situation is unlikely to change significantly through the summer; the three month outlook suggests normal levels will dominate, but with below-normal levels persisting in parts of north-east and southern England (although there is a possibility that levels in some parts of Wessex may return to normal).

For further information see the full Hydrological Outlook for June.

April 2015 overview

2015-05-20T17:21:00.000+01:00

Groundwater levels, April 2015

With little rainfall and some very warm weather, soil moisture deficits (SMDs) climbed steeply through April and, by month end, were substantially above average across the main aquifer areas (SMDs were double the typical end-of-April magnitude across the Chalk outcrop).

Consequently, levels fell at index wells throughout the country, with a few exceptions: the slowly-responding Chalk at Therfield Rectory and Dial Farm in eastern England, the Permo-Triassic sandstones at Nuttalls Farm and the Carboniferous Limestone at Alstonfield in the Midlands.

In the Chalk, levels were generally still within the normal range but below average for the time of year in Yorkshire, Northern Ireland and Dorset-Wiltshire, whilst they remained above average in the eastern part of the North Downs and upper Lee valley of Hertfordshire. However, compared with the exceptionally high groundwater levels in the Chalk in April 2014, when groundwater flooding was still present in some areas, they are now up to 4 m lower across southern England (and over 6 m and 12 m lower at Therfield Rectory and Stonor Park, respectively).

Groundwater level hydrograph, Stonor Park (unconfined Berkshire Downs Chalk)

In the fast responding Jurassic and Magnesian limestones, levels remained average or below and in the slow responding Permo-Triassic sandstones they were average or above (still exceptionally high at Newbridge, an area receiving above‑average autumn and winter rainfall, and Nuttalls Farm). Groundwater levels in the Lower Greensand of south-east England remained above average. With the modest rise in level at Alstonfield, Carboniferous Limestone levels were in the normal range in both Derbyshire and south Wales.

As little recharge is anticipated from now until the autumn, the current picture is likely to persist unless substantial late spring or summer rainfall is received.

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

Hydrological Outlook from May 2015

2015-05-20T16:52:00.003+01:00

The latest Hydrological Outlook is available!

Normal groundwater levels were widespread across the Chalk in April, but with below-normal levels in north-east England and Wessex contrasting with above-normal levels at a few boreholes in the south-east. Groundwater levels were variable in other aquifers, with above-normal levels in parts of the Permo-Triassic sandstone.

With evapotranspiration increasing and seasonal recessions generally well established, the outlook for both one and three months is for a broadly similar situation to persist. Levels in most aquifers are likely to be normal or below, with above-normal levels largely confined to some central and northern parts of the Permo-Triassic sandstone aquifer. Below normal levels are likely over the next three months in western and north-east England, with the possibility of notably low levels in some localities.

For further information see the full Hydrological Outlook for May.

March 2015 overview

2015-04-22T14:50:00.001+01:00

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].

Hydrological Outlook from April 2015

2015-04-16T11:08:00.003+01:00

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.

Hydrological Outlook from August 2014

2014-08-20T15:02:00.001+01:00

The latest Hydrological Outlook states that the groundwater levels in August will generally be unaffected by the amount of rainfall we have. This is because large soil moisture deficits have built up over the summer and rainfall will not reach the water table while these deficits exist.

Looking further ahead, the prediction for precipitation over the next 3 months is not a clear "wet" or "dry" scenario: "The probability that UK precipitation for August-September-October will fall into the driest of five categories is around 20% and the probability that it will fall into the wettest category is 25-30%". The timing of the soil moisture deficit being overcome by rainfall (and the reduced efforts of sunshine and plants in evaporation and transpiration), and thus the groundwater recharge season starting, will depend upon when the rain falls, and how persistent it is.

The general outlook is for groundwater levels to be in the near-normal range across the majority of aquifers.

For further information see the full Hydrological Outlook for August.

[Apologies for not posting this sooner.]

July 2014 overview

2014-08-19T16:39:00.000+01:00

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

Groundwater outlook - from July 2014

2014-07-18T09:42:00.000+01:00

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.

June 2014 overview

2014-07-16T16:45:00.000+01:00

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].