Groundwater Levels the Majority of Groundwater Sites in Wessex Are ‘Normal’ Or ‘Above Normal’ for the Time of Year

Monthly water situation report Wessex Area

Summary – February 2016 February rainfall was 136% of the long term average (LTA) but was distributed mainly in the first 8 days and then around mid month with the last half of the month being dry. The last 3 months have all had above average rainfall resulting in the 3 month total being 132% LTA. Rivers responded to the rainfall then were predominantly in recession from mid month. Soils remain wet close to capacity. Most groundwater sites have had significant recharge and are all normal or above for the time of year. Reservoir storage is almost at its maximum; Bristol water is at 99% of the total reservoir storage and Wessex Water is at capacity.

Rainfall The start of the month was wet, 63% of Februarys rainfall fell within the first eight days. The rest of the month was mostly dry apart from a couple of wet days around the 17th. The average rainfall total across the Wessex Area was 136% of LTA (88 mm). Rainfall map and graph

Soil Moisture Deficit The soil is wet, as expected for the time of year. The average soil moisture deficit across Wessex on 1 March 2016 was 1.08 mm, well below the LTA of 2.96 mm. SMD graph and maps

River Flows River flows across the Wessex area were ‘exceptionally high’ around 6 February and the 18 February in response to the precipitation received at the start and middle of the month. Many of the stations in the north and along the southern edge of Wessex are ‘above normal’ or experiencing flows above the LTA. At month end all river flows in Wessex were in recession. River flow map and graphs

Groundwater Levels The majority of groundwater sites in Wessex are ‘normal’ or ‘above normal’ for the time of year. Two of the sites have ‘exceptionally high’ values and represent the characteristics of the aquifer. Groundwater map and graphs

Reservoir Storage Reservoir levels for Wessex are almost at full capacity and have been for the duration of February. Bristol water is 99% full and Wessex Water sites are 100%. Reservoir graphs

All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained herein. www.gov.uk/environment-agency © Environment Agency 2016

Flood Warnings and Alerts Area Flood Warnings Flood Alerts Wessex 9 ( 3 were coastal) 389 (339 were coastal)

Sites Providing Stream Support River Site End of Month Status River Allen Wyke Down Off Chitterne Brook Codford Road Off Gussage Stream Gussage All Saints Off Devil’s Brook Dewlish WDX Off River Piddle Briantspuddle Off South Winterbourne Winterbourne Abbas Off Pimperne Stream Pimperne Off Watergates Stream Watergates On River Wylye Brixton Deverill Off River Wylye Kingston Deverill Off Rodbourne Brook Lower Stanton St. Quinton Off Tetbury Avon Tetbury Off Sherston Avon Stanbridge Off Luckington Brook Luckington Off Gauze Brooke Hullavington Off Charlton Stream Charlton Off Chalfield Brook South Wraxall Off Chalfield Brook Little Chalfield Off

Abstraction Licences Subject to Cease or Restrict Catchment End of Month Status Hampshire Avon None Dorset Frome None Stour None Piddle None Bride None Wylye None Bristol Avon None Somerset 1 cease

Glossary

Author: Wessex Hydrology

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Rainfall

Figure 1.1: Total rainfall for hydrological areas across England for the current month (February), the last three months, the last six months and the last 12 months, classed relative to an analysis of respective historic totals. Final NCIC (National Climate Information Centre) data based on the Met Office 5km gridded rainfall dataset derived from rain gauges (Source: Met Office © Crown Copyright, 2016). Provisional data based on Environment Agency 1km gridded rainfall dataset derived from Environment Agency intensity rain gauges. Crown copyright. All rights reserved. Environment Agency, 100026380, 2016.

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Above 100% LTA rainfall Below 100% LTA rainfall

1-Month Period for South West - Wessex NCIC

250%

200%

150%

100% Percentage of LTA

50% Feb Feb May May Nov Nov Aug 0% Aug ------14 15 14 15 14 15 14 15

Figure 1.2: Monthly rainfall totals as a percentage of the 1961 – 1990 long term average. Produced using final and provisional NCIC (National Climate Information Centre) data. (Source: Met Office © Crown Copyright, 2016).

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Soil Moisture Deficit

Less than historic minimum Greater than historic maximum ..... 1961-1990 long term average ── Latest data ── 2014

100

Soil moisture deficit (mm) deficit moisture Soil 120

140

160 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 2.1: Latest soil moisture deficit compared to previous year, maximum, minimum, and 1961 – 1990 long term average. Weekly MORECS data for real land use (Source: Met Office © Crown Copyright, 2016).

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Figure 2.2: Soil moisture deficits for week ending 01 February 2016. Top map shows actual soil moisture deficits (mm). Bottom map shows the difference (mm) of the actual from the 1961-90 long term average soil moisture deficits. MORECS data for real land use (Source: Met Office © Crown Copyright, 2016). Crown copyright. All rights reserved. Environment Agency, 100026380, 2016. Return to Summary

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River Flow

Figure 3.1: Monthly mean river flows at indicator sites for February 2016, expressed as a percentage of the respective long term average and classed relative to an analysis of historic February monthly means (Source: Environment Agency). Crown copyright. All rights reserved. Environment Agency, 100026380, 2016.

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Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Tone at Bishops Hull Yeo at Pen Mill Ranking derived from data for the period 01/02/1961 to 31/12/2012 Ranking derived from data for the period 31/10/1963 to 31/12/2012

20 February mean flow 25 February mean flow 8.394 cumecs 18 5.078 cumecs 158% LTA 119% LTA 16 20 14

12 15 10

8 10

4 5 Daily Mean Flow(cumecs) Daily Mean Flow(cumecs) 2

0 0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

Upper Brue at Lovington Bristol Avon at Bathford Ranking derived from data for the period 01/10/1964 to 31/12/2012 Ranking derived from data for the period 27/10/1969 to 31/12/2012

12 140 February mean flow February mean flow 3.813 cumecs 46.4 cumecs 121% LTA 120 130% LTA 10

100 8

80 6 60

4 40

Daily Mean Flow(cumecs) 2 Daily Mean Flow(cumecs) 20

0 0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

Somerset Frome at Tellisford Bristol Avon at Great Somerford Ranking derived from data for the period 01/09/1961 to 31/12/2012 Ranking derived from data for the period 16/12/1963 to 31/12/2012

25 February mean flow February mean flow 7.738 cumecs 20 9.185 cumecs 126% LTA 154% LTA 20

10 10

5 5 Daily Mean Flow(cumecs) Daily Mean Flow(cumecs)

0 0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

Middle Stour at Hammoon Dorset Frome at East Stoke Combined Ranking derived from data for the period 01/03/1968 to 31/12/2012 Ranking derived from data for the period 01/10/1965 to 31/12/2012

25 February mean flow February mean flow 60 14.001 cumecs 14.877 cumecs 124% LTA 136% LTA 20 50

40 15

30 10

5 Daily Mean Flow(cumecs) 10 Daily Mean Flow(cumecs)

0 0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

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Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Piddle at Baggs Mill Wylye at South Newton Ranking derived from data for the period 01/01/1964 to 31/12/2012 Ranking derived from data for the period 01/01/1967 to 31/12/2012

10 16 February mean flow February mean flow 8.584 cumecs 9.334 cumecs 9 196% LTA 14 120% LTA 8 12 7 10 6

5 8

4 6 3 4 2 Daily Mean Flow(cumecs) Daily Mean Flow(cumecs) 2 1

0 0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

Upper Hampshire Avon at Amesbury Stour at Throop Ranking derived from data for the period 01/02/1965 to 31/12/2012 Ranking derived from data for the period 01/01/1973 to 31/12/2012

12 80 February mean flow February mean flow 6.477 cumecs 37.129 cumecs 107% LTA 70 149% LTA 10

8 50

6 40

30 4

Daily Mean Flow(cumecs) 2 Daily Mean Flow(cumecs) 10

0 0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

Lower Hampshire Avon at Knapp Mill Washford at Beggearn Huish Ranking derived from data for the period 01/01/1975 to 31/12/2012 Ranking derived from data for the period 01/01/1967 to 31/12/2012

100 5.0 February mean flow February mean flow 37.9 cumecs 2.555 cumecs 90 4.5 100% LTA 170% LTA 80 4.0

70 3.5

60 3.0

50 2.5

40 2.0

30 1.5

20 1.0 Daily Mean Flow(cumecs) Daily Mean Flow(cumecs) 10 0.5

0 0.0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

Bristol Frome at Frenchay Isle at Ashford Mill Ranking derived from data for the period 01/09/1961 to 31/12/2012 Ranking derived from data for the period 01/10/1962 to 31/12/2012

16 12 February mean flow February mean flow 4.256 cumecs 3.252 cumecs 14 154% LTA 148% LTA 10

8 10

8 6

6 4

Daily Mean Flow(cumecs) Daily Mean Flow(cumecs) 2 2

0 0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

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Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Asker at Bridport East Bridge Sydling Water at Sydling St Nicholas Ranking derived from data for the period 01/03/1996 to 31/12/2012 Ranking derived from data for the period 01/12/1969 to 31/12/2012

4.0 0.7 February mean flow February mean flow 1.41 cumecs 0.533 cumecs 167% LTA 3.5 157% LTA 0.6

3.0 0.5

2.5 0.4 2.0 0.3 1.5

0.2 1.0 Daily Mean Flow(cumecs) Daily Mean Flow(cumecs) 0.5 0.1

0.0 0.0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

Wey at Broadwey Middle Hampshire Avon at East Mills Combined Ranking derived from data for the period 01/09/1975 to 31/12/2012 Ranking derived from data for the period 01/11/1965 to 31/12/2012

1.4 60 February mean flow February mean flow 1.001 cumecs 32.019 cumecs 116% LTA 1.2 173% LTA 50

1.0 40

0.8 30 0.6

20 0.4

Daily Mean Flow(cumecs) Daily Mean Flow(cumecs) 10 0.2

0.0 0 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16 29-Apr-15 29-Jun-15 29-Aug-15 29-Oct-15 29-Dec-15 29-Feb-16

Figure 3.2: Indicator river flow sites for Wessex. Daily mean flow compared to an analysis of historic daily mean flows. (Source: Environment Agency).

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Groundwater Levels

Figure 4.1: Groundwater levels for indicator sites at the end of February 2016, classed relative to an analysis of respective historic February levels (Source: Environment Agency). Geological map reproduced with permission from UK Groundwater Forum, BGS © NERC. Note: groundwater levels are reported at different times during the month and therefore may not be fully representative of levels at the month end. Crown copyright. All rights reserved. Environment Agency, 100026380, 2016.

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Allington No2 Ashton Farm Ranking derived from data for the period Oct-1974 to Dec-2012 Ranking derived from data for the period Feb-1974 to Dec-2012

72 80 71 78 70 76 69 74 68 72 67 70 66 Level (mAOD) Level (mAOD) Level 68 65 66 64 64 63 May-13 Sep-13 Jan-14 May-14 Sep-14 Jan-15 May-15 Sep-15 Jan-16 May-13 Sep-13 Jan-14 May-14 Sep-14 Jan-15 May-15 Sep-15 Jan-16

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Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Chantry No1 Didmarton 1 Ranking derived from data for the period Feb-1974 to Dec-2012 Ranking derived from data for the period Nov-1975 to Dec-2012

154 98 93 152 88 83 150 78 148 73 Level (mAOD) Level (mAOD) Level 68 146 63 144 58 May-13 Sep-13 Jan-14 May-14 Sep-14 Jan-15 May-15 Sep-15 Jan-16 May-13 Sep-13 Jan-14 May-14 Sep-14 Jan-15 May-15 Sep-15 Jan-16

Overcompton Tilshead Ranking derived from data for the period Sep-1971 to Dec-2012 Ranking derived from data for the period Jan-1966 to Dec-2012

60 98 59 93 58

88 57 Level (mAOD) Level Level (mAOD) Level 56 83

55 78 May-13 Sep-13 Jan-14 May-14 Sep-14 Jan-15 May-15 Sep-15 Jan-16 May-13 Sep-13 Jan-14 May-14 Sep-14 Jan-15 May-15 Sep-15 Jan-16

Tilshead Borehole was artesian for January and February 2014

Woodyates Kingston Russell Road Ranking derived from data for the period Jan-1942 to Dec-2012 Ranking derived from data for the period Jan-1974 to Dec-2012

121 102 119 97 117

92 115 113 87 111 82 109 Level (mAOD) Level Level (mAOD) Level 107 77 105 72 103 67 101 May-13 Sep-13 Jan-14 May-14 Sep-14 Jan-15 May-15 Sep-15 Jan-16 May-13 Sep-13 Jan-14 May-14 Sep-14 Jan-15 May-15 Sep-15 Jan-16

Figure 4.2: Indicator groundwater level sites for major aquifers. Daily groundwater levels compared to analysis of historic end month levels (Source: Environment Agency, 2016).

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Reservoir Stocks

── 2016 ── 2014 ── 1995 ── 1976 ..... 100% live capacity

Wessex Water - Clatworthy Wessex Water - Sutton Bingham

100 100

80 80

60 60

40 40 Percentage oflive capacity Percentage oflive capacity 20 20

0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Wessex Water - Total Reservoir Storage Bristol Water - Total Reservoir Storage

100 100

80 80

60 60

40 40 Percentage oflive capacity Percentage oflive capacity 20 20

0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 5.1: Reservoir stocks in Wessex (Source: Wessex Water and Bristol Water).

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Glossary

Term Definition

Aquifer A geological formation able to store and transmit water.

Areal average rainfall The estimated average depth of rainfall over a defined area. Expressed in depth of water (mm).

Artesian The condition where the groundwater level is above ground surface but is prevented from rising to this level by an overlying continuous low permeability layer, such as clay.

Artesian borehole Borehole where the level of groundwater is above the top of the borehole and groundwater flows out of the borehole when unsealed.

Cumecs Cubic metres per second (m3s-1)

Effective rainfall The rainfall available to percolate into the soil or produce river flow. Expressed in depth of water (mm).

Flood Alert/Flood Warning Three levels of warnings may be issued by the Environment Agency. Flood Alerts indicate flooding is possible. Flood Warnings indicate flooding is expected. Severe Flood Warnings indicate severe flooding.

Groundwater The water found in an aquifer.

Long term average (LTA) The arithmetic mean calculated from the historic record, usually based on the period 1961-1990. However, the period used may vary by parameter being reported on (see figure captions for details).

mAOD Metres Above Ordnance Datum (mean sea level at Newlyn Cornwall).

MORECS Met Office Rainfall and Evaporation Calculation System. Met Office service providing real time calculation of evapotranspiration, soil moisture deficit and effective rainfall on a 40 x 40 km grid.

Naturalised flow River flow with the impacts of artificial influences removed. Artificial influences may include abstractions, discharges, transfers, augmentation and impoundments.

NCIC National Climate Information Centre. NCIC area monthly rainfall totals are derived using the Met Office 5 km gridded dataset, which uses rain gauge observations.

Recharge The process of increasing the water stored in the saturated zone of an aquifer. Expressed in depth of water (mm).

Reservoir gross capacity The total capacity of a reservoir.

Reservoir live capacity The capacity of the reservoir that is normally usable for storage to meet established reservoir operating requirements. This excludes any capacity not available for use (e.g. storage held back for emergency services, operating agreements or physical restrictions). May also be referred to as ‘net’ or ‘deployable’ capacity.

Soil moisture deficit (SMD) The difference between the amount of water actually in the soil and the amount of water the soil can hold. Expressed in depth of water (mm).

Categories Exceptionally high Value likely to fall within this band 5% of the time Notably high Value likely to fall within this band 8% of the time Above normal Value likely to fall within this band 15% of the time Normal Value likely to fall within this band 44% of the time Below normal Value likely to fall within this band 15% of the time Notably low Value likely to fall within this band 8% of the time

Exceptionally low Value likely to fall within this band 5% of the time

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Rainfall Catchments

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