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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 2020
Monthly water situation report
Summary – December 2020 December was a very wet month with a total average rainfall of 108 mm (195% of the LTA) across East Anglia. The river flows has increased at all the indicator sites with majority of the sites reporting an exceptionally high flows. Soil Moisture Deficit (SMD) has decreased and ended the month with a below normal SMD of 3mm. The groundwater has continue to recharge at majority of the indicator sites with all the sites reporting a normal or higher ground water levels. The reservoir levels at all the sites are above their normal operating curves and some of the groundwater support schemes have been able to reduced operation.
Rainfall East Anglia as a whole received an exceptionally high amount of rainfall with a total averaged rainfall of 108 mm in December which was 195% of the Long Term Average (LTA). The rainfall varied across the area with majority of the catchments receiving an exceptionally high amount of rainfall (relative to the monthly LTA) making it the second wettest December since the record started in 1981. Over the past 12 months, rainfall across the area has been 115% of the LTA (Above Normal category), and over the winter period to date (the past 3 months) rainfall has been 154% of the LTA (Notably high category). The 12-months accumulation of rainfall surplus has increased to 688 mm for the time of the year.
Soil Moisture Deficit/Recharge Soil moisture deficits (SMD) continues to decreased following the exceptionally high rainfall in December and is fairly consistent across the area. By the end of December SMD for the area as a whole had decreased to 3 mm, which is in the below normal category.
River Flows The monthly river flows has increased at all the indicator sites as a results of an exceptionally high rain falling on the saturated ground in December. All the indicator sites has reported a notably high or higher flows with majority of the sites (62% out of 21 indicator sites) reporting an exceptionally high flows for the time of the year.
Groundwater Levels In response to the below normal SMD across East Anglia, the groundwater continues to recharge and levels has increased at all indicator sites with the exception of Hazlewood Common in the Sufflok Crag. Out of the 20 indicator sites all the sites has reported a normal or higher groundwater levels with 4 sites (viz., Fringford, Biggleswade, Bury St. Edmunds and Washpit Farm) reporting exceptionally high levels in December.
Reservoir Storage/Water Resource Zone Stocks The reservoir storage levels have increased at 3 out of the 5 indicator sites. All the Indicator sites reported a normal storage level with the exception of Ardleigh reporting below normal storage level. The reservoir levels at all the sites are above their normal operating curves for the time of the year.
Environmental Impact Majority of the support schemes had been able to turn off operation during December. The Lodes-Granta groundwater support scheme has 2 out of 6 pumps operating and there are no pumps operating at the Rhee, the Hiz, the Thet and the Little Ouse by the end of December.
East Anglia
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 2020
Forward Look Probabilistic ensemble projections for river flows at key sites March 2021: There is a reduced probability of exceptionally low river flows at all the key sites with an increased probability of exceptionally high flows at the river Stiffkey, Ely Ouse and Ivel in March. June 2021: There is a reduce probability of exceptionally low river flows at all the key sites with a reduce probability of notably low flows at majority of the key sites. Probabilistic ensemble projections for groundwater levels in key aquifers March 2021: The probability of groundwater levels to be in the below normal or lower category has reduced at all the key sites for March with an increased probability of exceptionally high groundwater levels at majority of the key sites. September 2021: The probability of groundwater levels to be in the below normal or lower category has reduced at all the key sites with an increased probability of above normal groundwater levels at majority of the key indicator sites in September. Author: Hydrology & Operations Contact details: 03708506506
© Environment Agency 2020
Rainfall December 2020
© Environment Agency 2020
Above average rainfall Below average rainfall
0%
50%
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200%
250%
Ja
n-2
0
Fe
b-2
0
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r-20
Apr-2
0
Ma
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0
Ju
n-2
0
Ju
l-20
Aug
-20
Sep
-20
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Nov-2
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Dec-2
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1-Month Period for East Anglia
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-20
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-20
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1-Month Period for Upper Bedford Ouse
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Ja
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l-20
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-20
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-20
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1-Month Period for Lower Bedford Ouse
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Ja
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Aug
-20
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-20
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No
v-2
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c-2
0
1-Month Period for Central Area Fenland
0%
50%
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250%
Ja
n-2
0
Fe
b-2
0
Ma
r-20
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0
Ma
y-2
0
Ju
n-2
0
Ju
l-20
Aug
-20
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-20
Oct-2
0
Nov-2
0
Dec-2
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1-Month Period for Cam
0%
50%
100%
150%
200%
250%
Ja
n-2
0
Fe
b-2
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Ma
r-20
Apr-2
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Ma
y-2
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Ju
n-2
0
Ju
l-20
Aug
-20
Sep
-20
Oct-2
0
Nov-2
0
Dec-2
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1-Month Period for NW Norfolk and Wissey
0%
50%
100%
150%
200%
250%
Ja
n-2
0
Fe
b-2
0
Ma
r-20
Apr-2
0
Ma
y-2
0
Ju
n-2
0
Ju
l-20
Aug
-20
Sep
-20
Oct-2
0
Nov-2
0
Dec-2
0
1-Month Period for Little Ouse and Lark
0%
50%
100%
150%
200%
250%
Ja
n-2
0
Fe
b-2
0
Ma
r-20
Apr-2
0
Ma
y-2
0
Ju
n-2
0
Ju
l-20
Aug
-20
Sep
-20
Oct-2
0
Nov-2
0
Dec-2
0
1-Month Period for North Norfolk
© Environment Agency 2020
Above average rainfall Below average rainfall
0%
50%
100%
150%
200%
250%
Ja
n-2
0
Fe
b-2
0
Ma
r-20
Apr-2
0
Ma
y-2
0
Ju
n-2
0
Ju
l-20
Aug
-20
Sep
-20
Oct-2
0
Nov-2
0
Dec-2
0
1-Month Period for Broadland Rivers
0%
50%
100%
150%
200%
250%
Ja
n-2
0
Fe
b-2
0
Ma
r-20
Apr-2
0
Ma
y-2
0
Ju
n-2
0
Ju
l-20
Aug
-20
Sep
-20
Oct-2
0
Nov-2
0
Dec-2
0
1-Month Period for East Suffolk
0%
50%
100%
150%
200%
250%
300%
Ja
n-2
0
Fe
b-2
0
Ma
r-20
Apr-2
0
Ma
y-2
0
Ju
n-2
0
Ju
l-20
Aug
-20
Sep
-20
Oct-2
0
No
v-2
0
De
c-2
0
1-Month Period for North Essex
0%
50%
100%
150%
200%
250%
300%
350%
Ja
n-2
0
Fe
b-2
0
Ma
r-20
Apr-2
0
Ma
y-2
0
Ju
n-2
0
Ju
l-20
Aug
-20
Sep
-20
Oct-2
0
No
v-2
0
De
c-2
0
1-Month Period for South Essex
400
425
450
475
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525
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575
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J F M A M J J A S O N D
mm
Monthly Rainfall Surplus/Deficit
Annual Mean 1961-90 Total for last 12 months
© Environment Agency 2020
Soil Moisture Deficit
─── 2020-21 ─ ─ ─ 2019-20 Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data
© Environment Agency 2020
River Flow December 2020
Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Cappenham, TOVERanking derived from data for the period Feb-1962 to Dec-2017
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Willen, OUZELRanking derived from data for the period Jan-1962 to Dec-2017
© Environment Agency 2020
Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data
0
1
2
3
4
5
6
7
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Burnt Mill, RHEERanking derived from data for the period Oct-1962 to Dec-2017
0
10
20
30
40
50
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Roxton, GREAT OUSERanking derived from data for the period Oct-1972 to Dec-2017
0
2
4
6
8
10
12
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Blunham, IVELRanking derived from data for the period Aug-1959 to Dec-2017
0
10
20
30
40
50
60
70
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Offord (Gross Flows), GREAT OUSERanking derived from data for the period Jan-1972 to Dec-2017
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Dernford, CAMRanking derived from data for the period Feb-1949 to Dec-2017
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Temple, LARKRanking derived from data for the period Nov-1960 to Dec-2017
0
2
4
6
8
10
12
14
16
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Abbey Heath, LITTLE OUSERanking derived from data for the period Jun-1968 to Dec-2017
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Northwold Total, WISSEYRanking derived from data for the period Jul-1983 to Dec-2012
© Environment Agency 2020
Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data
0
10
20
30
40
50
60
70
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Denver, ELY OUSERanking derived from data for the period Nov-1971 to Dec-2017
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Marham, NARRanking derived from data for the period Apr-1982 to Dec-2017
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Heacham, HEACHAMRanking derived from data for the period Nov-1965 to Dec-2017
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Colney, YARERanking derived from data for the period Jan-1970 to Dec-2017
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Ingworth, BURERanking derived from data for the period Jan-1970 to Dec-2017
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Burnham Overy, BURN Ranking derived from data for the period Jan-1970 to Dec-2017
0
2
4
6
8
10
12
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Swanton Morley Total, WENSUMRanking derived from data for the period Jan-1970 to Dec-2017
0.0
2.0
4.0
6.0
8.0
10.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Needham Weir Total, WAVENEY (LOWER)Ranking derived from data for the period Jan-1970 to Dec-2017
© Environment Agency 2020
Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Bramford, GIPPING Ranking derived from data for the period Jan-1970 to Dec-2017
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Lexden, COLNERanking derived from data for the period Jan-1970 to Dec-2017
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Mar-20 May-20 Jul-20 Sep-20 Nov-20 Jan-21
Flo
w (
cu
me
cs)
Springfield, CHELMERRanking derived from data for the period Jan-1970 to Dec-2017
© Environment Agency 2020
Groundwater Levels December 2020
Exceptionally high Notably high Above normal Normal
Below normal Notably low Exceptionally low ─── Latest data
93
94
95
96
97
98
99
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Fringford - GREAT OOLITERanking derived from data for the period Sep-1980 to Dec-2017
66
67
68
69
70
71
72
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Bath Spring, Charlton - IVEL CHALKRanking derived from data for the period Mar-1993 to Dec-2017
© Environment Agency 2020
Exceptionally high Notably high Above normal Normal
Below normal Notably low Exceptionally low ─── Latest data
25.0
25.3
25.6
25.9
26.2
26.5
26.8
27.1
27.4
27.7
28.0
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Biggleswade - IVEL SANDSTONERanking derived from data for the period Mar-1968 to Dec-2017
70
75
80
85
90
95
100
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Therfield Rectory - N HERTS CHALKRanking derived from data for the period Jan-1883 to Dec-2017
32
37
42
47
52
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Redlands Hall, Ickleton - CAM CHALKRanking derived from data for the period Aug-1963 to Dec-2017
24
25
26
27
28
29
30
31
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Linton - CAM CHALKRanking derived from data for the period Jan-1980 to Dec-2017
12
13
14
15
16
17
18
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Gog Magog, Stapleford - CAM CHALKRanking derived from data for the period Jan-1980 to Dec-2017
25
26
27
28
29
30
31
32
33
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Bury St Edmunds - UPPER LARK CHALKRanking derived from data for the period May-1983 to Dec-2017
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
16.5
17.0
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Newmarket - SNAIL CHALKRanking derived from data for the period Feb-1983 to Dec-2017
23
24
25
26
27
28
29
30
31
32
33
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Kenninghall - LITTLE OUSE CHALKRanking derived from data for the period Aug-1973 to Dec-2017
© Environment Agency 2020
Exceptionally high Notably high Above normal Normal
Below normal Notably low Exceptionally low ─── Latest data
23
24
25
26
27
28
29
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Breckland - WISSEY CHALKRanking derived from data for the period Jan-1971 to Nov-2017
40
41
42
43
44
45
46
47
48
49
50
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Washpit Farm, Rougham - NW NORFOLK CHALKRanking derived from data for the period May-1950 to Dec-2017
36
37
38
39
40
41
42
43
44
45
46
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Bircham Newton - NW NORFOLK CHALKRanking derived from data for the period Mar-1995 to Sep-2017
12.0
14.0
16.0
18.0
20.0
22.0
24.0
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Castle Farm, Offton - MID SUFFOLK CHALKRanking derived from data for the period Mar-1967 to Dec-2017
17
18
19
20
21
22
23
24
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Old Primary School, South CreakeNW NORFOLK CHALK
Ranking derived from data for the period Oct-1971 to Dec-2017
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Hazlewood Common - SUFFOLK CRAGRanking derived from data for the period Oct-1988 to Feb-2020
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
The Spinney, Costessey - WENSUM CHALKRanking derived from data for the period Oct-1971 to Dec-2017
24.0
25.0
26.0
27.0
28.0
29.0
30.0
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Smeetham Hall Cottages, Bulmer - ESSEX CHALKRanking derived from data for the period Jan-1964 to Dec-2017
© Environment Agency 2020
Exceptionally high Notably high Above normal Normal
Below normal Notably low Exceptionally low ─── Latest data
54.0
54.5
55.0
55.5
56.0
56.5
57.0
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Hindolveston - NORFOLK CHALKRanking derived from data for the period Sep-1984 to Nov-2017
30.0
30.5
31.0
31.5
32.0
32.5
33.0
33.5
34.0
Mar-18 Jul-18 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20
Le
ve
l (m
AO
D)
Rook Hall, Braiseworth - SUFFOLK CHALKRanking derived from data for the period Jan-1980 to Dec-2017
© Environment Agency 2020
Reservoir Stocks December 2020
─── 2020-2021 ─── Normal Operating Curve ─── Drought Alert Curve ── ─ 1995-1996
0
10
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30
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60
70
80
90
100
Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov
Pe
rce
nta
ge
of liv
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ap
acity
Grafham
0
10
20
30
40
50
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Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov
Pe
rce
nta
ge
of liv
e c
ap
acity
Alton
© Environment Agency 2020
─── 2020-2021 ─── Normal Operating Curve ─── Drought Alert Curve ── ─ 1995-1996
0
10
20
30
40
50
60
70
80
90
100
Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov
Pe
rce
nta
ge
of liv
e c
ap
acity
Ardleigh
0
20
40
60
80
100
Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov
Pe
rce
nta
ge
of liv
e c
ap
acity
Abberton
Control curve 1Control curve 2
n.b. from 20/01/2014 Abberton %full is based on increased “19m.Volume”n.b. from 29/09/2014 Abberton %full is based on increased “20m.Volume”
0
10
20
30
40
50
60
70
80
90
100
Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov
Pe
rce
nta
ge
of liv
e c
ap
acity
Hanningfield
Control curve
© Environment Agency 2020
Forward Look – River Flows
Exceptionally high or low levels are those which would typically occur 5% of the time within the historic record. Notably high or low levels are those which would typically occur 8% of the time. Above normal or below normal levels are those which would typically occur 15% of the time. Normal levels are those which would typically occur 44% of the time within the historic record.
Probabilistic ensemble projections of river flows at key indicator sites in March 2021. Pie charts indicate probability, based on climatology, of the surface water flow at each site being e.g. exceptionally low for the time of year. (Source: Centre for Ecology and Hydrology, Environment Agency) Geological map reproduced with kind permission from UK Groundwater Forum, BGS © NERC. Crown copyright. All rights reserved. Environment Agency, 100026380, 2020. ^ “Naturalised” flows are projected for these sites’
© Environment Agency 2020
Exceptionally high or low levels are those which would typically occur 5% of the time within the historic record. Notably high or low levels are those which would typically occur 8% of the time. Above normal or below normal levels are those which would typically occur 15% of the time. Normal levels are those which would typically occur 44% of the time within the historic record.
Probabilistic ensemble projections of river flows at key indicator sites in June 2021. Pie charts indicate probability, based on climatology, of the surface water flow at each site being e.g. exceptionally low for the time of year. (Source: Centre for Ecology and Hydrology, Environment Agency) Geological map reproduced with kind permission from UK Groundwater Forum, BGS © NERC. Crown copyright. All rights reserved. Environment Agency, 100026380, 2020
© Environment Agency 2020
Forward Look - Groundwater
Exceptionally high or low levels are those which would typically occur 5% of the time within the historic record. Notably high or low levels are those which would typically occur 8% of the time. Above normal or below normal levels are those which would typically occur 15% of the time. Normal levels are those which would typically occur 44% of the time within the historic record.
Probabilistic ensemble projections of groundwater levels at key indicator sites for end of March 2021. Pie charts indicate probability, based on climatology, of the groundwater level at each site being e.g. exceptionally low for the time of year. (Source: Environment Agency) Geological map reproduced with kind permission from UK Groundwater Forum, BGS © NERC. Crown copyright. All rights reserved. Environment Agency, 100026380, 2020.
© Environment Agency 2020
Exceptionally high or low levels are those which would typically occur 5% of the time within the historic record. Notably high or low levels are those which would typically occur 8% of the time. Above normal or below normal levels are those which would typically occur 15% of the time. Normal levels are those which would typically occur 44% of the time within the historic record.
Probabilistic ensemble projections of groundwater levels at key indicator sites for end of September 2021. Pie charts indicate probability, based on climatology, of the groundwater level at each site being e.g. exceptionally low for the time of year. (Source: Environment Agency) Geological map reproduced with kind permission from UK Groundwater Forum, BGS © NERC. Crown copyright. All rights reserved. Environment Agency, 100026380, 2020.
© Environment Agency 2020
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 Flow
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. The water passing in the river, as measured.
Groundwater The water found in an aquifer, as measured.
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).
© Environment Agency 2020
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
