Water Situation Report Simple Storage Service
Monthly water situation report Devon and Cornwall Area Summary – September 2017 The rainfall that fell in September was ‘above normal’ for the time of year (157% of long term average). Overall, the soil moisture deficit decreased over the month. Monthly mean river flows in North Cornwall and at Fowey were classed as ‘exceptionally high’, which is reflective of the high rainfall in these areas. The groundwater level at Whitlands receded over the month but is still ‘normal’ for the time of year. Bussels No7A remains ‘below normal’ despite an increase in groundwater levels and Woodleys No1 continued to recede and is classed as ‘notably low’. Overall, reservoir storage has increased from 73% to 76%.
Rainfall There is a prominent divide between the rainfall received in the east and the west of the area. All rainfall catchments in Cornwall are ‘notably high’ and the only catchment within Devon that was ‘normal was the ‘Teign and Torbay’; all remaining Devon catchments are ‘above normal’. Overall, rainfall was ‘above normal’ across Devon and Cornwall. Rainfall ranged between 126% and 201% of long term average for each rainfall catchment. The Seaton, Looe and Fowey catchment received the highest long term average rainfall in the area. Rainfall maps and graph
Soil Moisture Deficit Overall, the soil moisture deficit has decreased since the end of August. The greatest deficit can still be seen in East Devon. SMD graph and map
River Flows The monthly mean river flows show that over half the areas were classed as ‘notably high’. Mid and East Devon were classed as ‘above normal’ and sites in North Cornwall and at Fowey were classed as ‘Exceptionally high’. The Seaton, Fowey and Looe hydrological rainfall catchment received the highest long term average rainfall which is reflected in the river flows in the area. At the end of the month, daily mean flows in North Devon were ‘normal’ and the Otter, Tamar and Camel were ‘above normal’. Both sites on the Dart and those at Fowey, Gannel and Kenwyn were ‘notably high’ and daily flows at the end of the month in the Axe and the Hayle were both ‘exceptionally high’, reflecting the high rainfall in these areas over the month. River flow map and graphs
Groundwater Levels The groundwater level at Whitlands has continued to recede over the month but remains ‘normal’ for the time of the year. Water levels at Bussels No7A increased over the month but remains as ‘below normal’. Woodleys No1 continued to recede gradually over the month and is classed as ‘notably low’. Groundwater map and graphs
Reservoir Storage Overall, reservoir storage has increased from 73% to 76%. Wimbleball decreased slightly from 60% to 57% whilst Colliford and Roadford both saw increases (76% to 81% and 68% to 71% respectively). Reservoir graphs Glossary Author: Devon and Cornwall Hydrology
Contact details: 03708 506506
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.
© Environment Agency 2017
Rainfall
Figure 1.1: Total rainfall for hydrological areas across Devon and Cornwall for the current month, 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, 2017). 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, 2017.
www.gov.uk/environment-agency
© Environment Agency 2017
Above 100% LTA rainfall
Below 100% LTA rainfall
1-Month Period for South West - Devon & Cornwall NCIC 250%
Percentage of LTA
200%
150%
100%
50%
0% Sep-17
Aug-17
Jul-17
Jun-17
May-17
Apr-17
Mar-17
Feb-17
Jan-17
Dec-16
Nov-16
Oct-16
Sep-16
Aug-16
Jul-16
Jun-16
May-16
Apr-16
Mar-16
Feb-16
Jan-16
Dec-15
Nov-15
Oct-15
Figure 1.2: Monthly rainfall totals as a percentage of the 1961 – 1990 long term average. 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, 2017). 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, 2017.
www.gov.uk/environment-agency
© Environment Agency 2017
Soil Moisture Deficit ..... ──
Less than historic minimum 1961-1990 long term average 2016
──
Greater than historic maximum Latest data
0
Soil moisture deficit (mm)
20
40
60
80
100
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, 2017).
www.gov.uk/environment-agency
© Environment Agency 2017
Month-end Soil Moisture Deficit (mm)
Soil moisture deficit (mm) Actual 160
Difference from LTA (mm) < - 75 -75 to -51 -50 to -26 -25 to -6 -5 to 5 6 to 25 26 to 50 51 to 75 > 75
Figure 2.2: Soil moisture deficits for week ending 29 September 2017. MORECS data for real land use (Source: Met Office © Crown Copyright, 2017). Crown copyright. All rights reserved. Environment Agency, 100026380, 2017.
www.gov.uk/environment-agency
© Environment Agency 2017
River Flow
Figure 3.1: Monthly mean river flows at indicator sites for September 2017, expressed as a percentage of the respective long term average and classed relative to an analysis of historic September monthly means (Source: Environment Agency). Crown copyright. All rights reserved. Environment Agency, 100026380, 2017. Exceptionally high Below normal
Notably high Notably low
Hayle at St Erth
Kenwyn at Truro Ranking derived from data for the period 31/10/1968 to 31/12/2012
2.0
September mean flow 0.652 cumecs 172% LTA
4.5 4.0 3.5
3.0 2.5 2.0 1.5 1.0
0.5
September mean flow 0.232 cumecs 193% LTA
1.8
Daily Mean Flow (cumecs)
Daily Mean Flow (cumecs)
Normal ─── Latest data
Ranking derived from data for the period 03/01/1968 to 31/12/2012
5.0
0.0 30-Nov-16
Above normal Exceptionally low
1.6 1.4
1.2 1.0 0.8 0.6 0.4
0.2
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
www.gov.uk/environment-agency
30-Sep-17
30-Nov-17
0.0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
© Environment Agency 2017
Exceptionally high Below normal
Notably high Notably low
Above normal Exceptionally low
Gannel at Gwills
Camel at Denby
Ranking derived from data for the period 01/12/1969 to 31/12/2012
Ranking derived from data for the period 31/08/1964 to 31/12/2012
4.0
35 September mean flow 0.894 cumecs 406% LTA
3.0
2.5 2.0 1.5 1.0 0.5
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
5
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
Tamar at Gunnislake 160 September mean flow 7.18 cumecs 311% LTA
25
20
15
10
5
30-Nov-17
September mean flow 25.4 cumecs 236% LTA
140
Daily Mean Flow (cumecs)
Daily Mean Flow (cumecs)
10
Ranking derived from data for the period 25/06/1956 to 31/12/2012
120
100 80 60 40 20
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
0 30-Nov-16
30-Nov-17
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
Torridge at Torrington
Taw at Umberleigh
Ranking derived from data for the period 31/07/1960 to 31/12/2012
Ranking derived from data for the period 30/09/1958 to 31/12/2012
140
September mean flow 15.4 cumecs 215% LTA
100
80
60
40
20
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
100
80
60
40
20
0 30-Nov-16
30-Nov-17
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
East Dart at Bellever
Dart at Austins Bridge
Ranking derived from data for the period 31/03/1964 to 31/12/2012
Ranking derived from data for the period 30/09/1958 to 31/12/2012
10
September mean flow 1.43 cumecs 181% LTA
9
Daily Mean Flow (cumecs)
7
6 5 4 3 2
30-Nov-17
September mean flow 9.77 cumecs 123% LTA
60
8
30-Nov-17
September mean flow 17.5 cumecs 211% LTA
120
Daily Mean Flow (cumecs)
120
Daily Mean Flow (cumecs)
15
Fowey at Restormel
140
Daily Mean Flow (cumecs)
20
Ranking derived from data for the period 31/03/1961 to 31/12/2012
30
0 30-Nov-16
25
0 30-Nov-16
30-Nov-17
35
0 30-Nov-16
September mean flow 8.49 cumecs 300% LTA
30
Daily Mean Flow (cumecs)
Daily Mean Flow (cumecs)
3.5
0.0 30-Nov-16
Normal ─── Latest data
50
40
30
20
10
1 0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
www.gov.uk/environment-agency
30-Sep-17
30-Nov-17
0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
© Environment Agency 2017
Exceptionally high Below normal
Notably high Notably low
Above normal Exceptionally low
Exe at Thorverton
Otter at Dotton
Ranking derived from data for the period 30/04/1956 to 31/12/2012
Ranking derived from data for the period 30/09/1962 to 31/12/2012
100
25
September mean flow 10.6 cumecs 158% LTA
90 80
Daily Mean Flow (cumecs)
Daily Mean Flow (cumecs)
Normal ─── Latest data
70
60 50 40 30 20
September mean flow 2.01 cumecs 110% LTA
20
15
10
5
10 0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
Axe at Whitford Ranking derived from data for the period 05/11/1964 to 31/12/2012
40 September mean flow 3.58 cumecs 129% LTA
Daily Mean Flow (cumecs)
35 30
25 20 15 10 5 0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
Figure 3.2: Indicator river flow sites for Devon and Cornwall. Daily mean flow compared to an analysis of historic daily mean flows. (Source: Environment Agency).
www.gov.uk/environment-agency
© Environment Agency 2017
Groundwater Levels
Figure 4.1: Groundwater levels for indicator sites at the end of September 2017, classed relative to an analysis of respective historic September 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, 2017. Notably high Notably low
Above normal Exceptionally low
Normal ─── Latest data
WHITLANDS
BUSSELS NO7A
Ranking derived from data for the period Sep-1984 to Dec-2012
Ranking derived from data for the period Nov-1971 to Dec-2012
89
26
89
26
88 88 87
Level (mAOD)
Level (mAOD)
Exceptionally high Below normal
25 25 24
87
24
86 Dec-14 Apr-15 Aug-15 Dec-15 Apr-16 Aug-16 Dec-16 Apr-17 Aug-17
23 Dec-14 Apr-15 Aug-15 Dec-15 Apr-16 Aug-16 Dec-16 Apr-17 Aug-17
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© Environment Agency 2017
Exceptionally high Below normal
Notably high Notably low
Above normal Exceptionally low
Normal ─── Latest data
WOODLEYS NO1 Ranking derived from data for the period Jan-1966 to Dec-2012
34 34
Level (mAOD)
33
33 32 32 31 31
30 Dec-14 Apr-15 Aug-15 Dec-15 Apr-16 Aug-16 Dec-16 Apr-17 Aug-17
Figure 4.2: Indicator groundwater level sites for major aquifers. End of month groundwater levels compared to analysis of historic end month levels (Source: Environment Agency, 2017).
Reservoir Stocks ──
──
2017
──
2016
..... 100% live capacity
1995
South West Water - Colliford
South West Water - Roadford
100
Percentage of live capacity
Percentage of live capacity
100
80
60
40
20
80
60
40
20
0
0 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
South West Water - Wimbleball
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Oct
Nov
Dec
South West Water - Total Reservoir Storage
100
Percentage of live capacity
100
Percentage of live capacity
Apr
80
60
40
20
80
60
40
20
0
0 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Figure 5.1: Reservoir stocks in Devon and Cornwall (Source: South West Water).
www.gov.uk/environment-agency
© Environment Agency 2017
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 (m 3s-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 Notably high Above normal Normal Below normal Notably low Exceptionally low
Value likely to fall within this band 5% of the time Value likely to fall within this band 8% of the time Value likely to fall within this band 15% of the time Value likely to fall within this band 44% of the time Value likely to fall within this band 15% of the time Value likely to fall within this band 8% of the time Value likely to fall within this band 5% of the time
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© Environment Agency 2017
Rainfall Catchments
Figure 6.1: Rainfall catchments in Devon and Cornwall. Crown copyright. All rights reserved. Environment Agency, 100026380, 2017.
www.gov.uk/environment-agency
© Environment Agency 2017
Rainfall There is a prominent divide between the rainfall received in the east and the west of the area. All rainfall catchments in Cornwall are ‘notably high’ and the only catchment within Devon that was ‘normal was the ‘Teign and Torbay’; all remaining Devon catchments are ‘above normal’. Overall, rainfall was ‘above normal’ across Devon and Cornwall. Rainfall ranged between 126% and 201% of long term average for each rainfall catchment. The Seaton, Looe and Fowey catchment received the highest long term average rainfall in the area. Rainfall maps and graph
Soil Moisture Deficit Overall, the soil moisture deficit has decreased since the end of August. The greatest deficit can still be seen in East Devon. SMD graph and map
River Flows The monthly mean river flows show that over half the areas were classed as ‘notably high’. Mid and East Devon were classed as ‘above normal’ and sites in North Cornwall and at Fowey were classed as ‘Exceptionally high’. The Seaton, Fowey and Looe hydrological rainfall catchment received the highest long term average rainfall which is reflected in the river flows in the area. At the end of the month, daily mean flows in North Devon were ‘normal’ and the Otter, Tamar and Camel were ‘above normal’. Both sites on the Dart and those at Fowey, Gannel and Kenwyn were ‘notably high’ and daily flows at the end of the month in the Axe and the Hayle were both ‘exceptionally high’, reflecting the high rainfall in these areas over the month. River flow map and graphs
Groundwater Levels The groundwater level at Whitlands has continued to recede over the month but remains ‘normal’ for the time of the year. Water levels at Bussels No7A increased over the month but remains as ‘below normal’. Woodleys No1 continued to recede gradually over the month and is classed as ‘notably low’. Groundwater map and graphs
Reservoir Storage Overall, reservoir storage has increased from 73% to 76%. Wimbleball decreased slightly from 60% to 57% whilst Colliford and Roadford both saw increases (76% to 81% and 68% to 71% respectively). Reservoir graphs Glossary Author: Devon and Cornwall Hydrology
Contact details: 03708 506506
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.
© Environment Agency 2017
Rainfall
Figure 1.1: Total rainfall for hydrological areas across Devon and Cornwall for the current month, 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, 2017). 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, 2017.
www.gov.uk/environment-agency
© Environment Agency 2017
Above 100% LTA rainfall
Below 100% LTA rainfall
1-Month Period for South West - Devon & Cornwall NCIC 250%
Percentage of LTA
200%
150%
100%
50%
0% Sep-17
Aug-17
Jul-17
Jun-17
May-17
Apr-17
Mar-17
Feb-17
Jan-17
Dec-16
Nov-16
Oct-16
Sep-16
Aug-16
Jul-16
Jun-16
May-16
Apr-16
Mar-16
Feb-16
Jan-16
Dec-15
Nov-15
Oct-15
Figure 1.2: Monthly rainfall totals as a percentage of the 1961 – 1990 long term average. 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, 2017). 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, 2017.
www.gov.uk/environment-agency
© Environment Agency 2017
Soil Moisture Deficit ..... ──
Less than historic minimum 1961-1990 long term average 2016
──
Greater than historic maximum Latest data
0
Soil moisture deficit (mm)
20
40
60
80
100
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, 2017).
www.gov.uk/environment-agency
© Environment Agency 2017
Month-end Soil Moisture Deficit (mm)
Soil moisture deficit (mm) Actual 160
Difference from LTA (mm) < - 75 -75 to -51 -50 to -26 -25 to -6 -5 to 5 6 to 25 26 to 50 51 to 75 > 75
Figure 2.2: Soil moisture deficits for week ending 29 September 2017. MORECS data for real land use (Source: Met Office © Crown Copyright, 2017). Crown copyright. All rights reserved. Environment Agency, 100026380, 2017.
www.gov.uk/environment-agency
© Environment Agency 2017
River Flow
Figure 3.1: Monthly mean river flows at indicator sites for September 2017, expressed as a percentage of the respective long term average and classed relative to an analysis of historic September monthly means (Source: Environment Agency). Crown copyright. All rights reserved. Environment Agency, 100026380, 2017. Exceptionally high Below normal
Notably high Notably low
Hayle at St Erth
Kenwyn at Truro Ranking derived from data for the period 31/10/1968 to 31/12/2012
2.0
September mean flow 0.652 cumecs 172% LTA
4.5 4.0 3.5
3.0 2.5 2.0 1.5 1.0
0.5
September mean flow 0.232 cumecs 193% LTA
1.8
Daily Mean Flow (cumecs)
Daily Mean Flow (cumecs)
Normal ─── Latest data
Ranking derived from data for the period 03/01/1968 to 31/12/2012
5.0
0.0 30-Nov-16
Above normal Exceptionally low
1.6 1.4
1.2 1.0 0.8 0.6 0.4
0.2
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
www.gov.uk/environment-agency
30-Sep-17
30-Nov-17
0.0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
© Environment Agency 2017
Exceptionally high Below normal
Notably high Notably low
Above normal Exceptionally low
Gannel at Gwills
Camel at Denby
Ranking derived from data for the period 01/12/1969 to 31/12/2012
Ranking derived from data for the period 31/08/1964 to 31/12/2012
4.0
35 September mean flow 0.894 cumecs 406% LTA
3.0
2.5 2.0 1.5 1.0 0.5
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
5
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
Tamar at Gunnislake 160 September mean flow 7.18 cumecs 311% LTA
25
20
15
10
5
30-Nov-17
September mean flow 25.4 cumecs 236% LTA
140
Daily Mean Flow (cumecs)
Daily Mean Flow (cumecs)
10
Ranking derived from data for the period 25/06/1956 to 31/12/2012
120
100 80 60 40 20
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
0 30-Nov-16
30-Nov-17
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
Torridge at Torrington
Taw at Umberleigh
Ranking derived from data for the period 31/07/1960 to 31/12/2012
Ranking derived from data for the period 30/09/1958 to 31/12/2012
140
September mean flow 15.4 cumecs 215% LTA
100
80
60
40
20
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
100
80
60
40
20
0 30-Nov-16
30-Nov-17
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
East Dart at Bellever
Dart at Austins Bridge
Ranking derived from data for the period 31/03/1964 to 31/12/2012
Ranking derived from data for the period 30/09/1958 to 31/12/2012
10
September mean flow 1.43 cumecs 181% LTA
9
Daily Mean Flow (cumecs)
7
6 5 4 3 2
30-Nov-17
September mean flow 9.77 cumecs 123% LTA
60
8
30-Nov-17
September mean flow 17.5 cumecs 211% LTA
120
Daily Mean Flow (cumecs)
120
Daily Mean Flow (cumecs)
15
Fowey at Restormel
140
Daily Mean Flow (cumecs)
20
Ranking derived from data for the period 31/03/1961 to 31/12/2012
30
0 30-Nov-16
25
0 30-Nov-16
30-Nov-17
35
0 30-Nov-16
September mean flow 8.49 cumecs 300% LTA
30
Daily Mean Flow (cumecs)
Daily Mean Flow (cumecs)
3.5
0.0 30-Nov-16
Normal ─── Latest data
50
40
30
20
10
1 0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
www.gov.uk/environment-agency
30-Sep-17
30-Nov-17
0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
© Environment Agency 2017
Exceptionally high Below normal
Notably high Notably low
Above normal Exceptionally low
Exe at Thorverton
Otter at Dotton
Ranking derived from data for the period 30/04/1956 to 31/12/2012
Ranking derived from data for the period 30/09/1962 to 31/12/2012
100
25
September mean flow 10.6 cumecs 158% LTA
90 80
Daily Mean Flow (cumecs)
Daily Mean Flow (cumecs)
Normal ─── Latest data
70
60 50 40 30 20
September mean flow 2.01 cumecs 110% LTA
20
15
10
5
10 0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
Axe at Whitford Ranking derived from data for the period 05/11/1964 to 31/12/2012
40 September mean flow 3.58 cumecs 129% LTA
Daily Mean Flow (cumecs)
35 30
25 20 15 10 5 0 30-Nov-16
31-Jan-17
31-Mar-17
31-May-17
31-Jul-17
30-Sep-17
30-Nov-17
Figure 3.2: Indicator river flow sites for Devon and Cornwall. Daily mean flow compared to an analysis of historic daily mean flows. (Source: Environment Agency).
www.gov.uk/environment-agency
© Environment Agency 2017
Groundwater Levels
Figure 4.1: Groundwater levels for indicator sites at the end of September 2017, classed relative to an analysis of respective historic September 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, 2017. Notably high Notably low
Above normal Exceptionally low
Normal ─── Latest data
WHITLANDS
BUSSELS NO7A
Ranking derived from data for the period Sep-1984 to Dec-2012
Ranking derived from data for the period Nov-1971 to Dec-2012
89
26
89
26
88 88 87
Level (mAOD)
Level (mAOD)
Exceptionally high Below normal
25 25 24
87
24
86 Dec-14 Apr-15 Aug-15 Dec-15 Apr-16 Aug-16 Dec-16 Apr-17 Aug-17
23 Dec-14 Apr-15 Aug-15 Dec-15 Apr-16 Aug-16 Dec-16 Apr-17 Aug-17
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Exceptionally high Below normal
Notably high Notably low
Above normal Exceptionally low
Normal ─── Latest data
WOODLEYS NO1 Ranking derived from data for the period Jan-1966 to Dec-2012
34 34
Level (mAOD)
33
33 32 32 31 31
30 Dec-14 Apr-15 Aug-15 Dec-15 Apr-16 Aug-16 Dec-16 Apr-17 Aug-17
Figure 4.2: Indicator groundwater level sites for major aquifers. End of month groundwater levels compared to analysis of historic end month levels (Source: Environment Agency, 2017).
Reservoir Stocks ──
──
2017
──
2016
..... 100% live capacity
1995
South West Water - Colliford
South West Water - Roadford
100
Percentage of live capacity
Percentage of live capacity
100
80
60
40
20
80
60
40
20
0
0 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
South West Water - Wimbleball
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Oct
Nov
Dec
South West Water - Total Reservoir Storage
100
Percentage of live capacity
100
Percentage of live capacity
Apr
80
60
40
20
80
60
40
20
0
0 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Figure 5.1: Reservoir stocks in Devon and Cornwall (Source: South West Water).
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© Environment Agency 2017
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 (m 3s-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 Notably high Above normal Normal Below normal Notably low Exceptionally low
Value likely to fall within this band 5% of the time Value likely to fall within this band 8% of the time Value likely to fall within this band 15% of the time Value likely to fall within this band 44% of the time Value likely to fall within this band 15% of the time Value likely to fall within this band 8% of the time Value likely to fall within this band 5% of the time
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Rainfall Catchments
Figure 6.1: Rainfall catchments in Devon and Cornwall. Crown copyright. All rights reserved. Environment Agency, 100026380, 2017.
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