hydrological summary - connecting repositories · 2012. 3. 26. · 2 area rainfall jan 2006 nov...

General

Jan

ua

ry 2

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6

Hydrological Summaryfor the United Kingdom

January was a dull and notably dry month across almost the entire country; the UK rainfall total is the 3rd lowest since1964. An especially arid episode, from the second week until well into February served to intensify drought conditionsin most areas. Consequently most reservoirs reported meagre storage increases but at month-end overall stocks forEngland and Wales were still only 2% below average, and well above corresponding stocks in 1997 and 1992. Stocksare, however, seasonally depressed in a number of southern reservoirs – the lowest on record (for January) at BewlWater. The drought’s clear regional dimension is further emphasised by the exceptionally low long term runoffaccumulations for many rivers in central and southern England; flows in many spring-fed streams are more typical ofthe mid-summer. In parts of the South-East especially (e.g. the Chilterns), the continuing lack of any substantialwinter recharge has left groundwater levels approaching long term minima. Two successive notably dry winters havemade for a fragile – but spatially variable – water resources outlook with the prospect of very depressed summer flowsand associated stress on the aquatic environment. The window of opportunity for the necessary groundwaterreplenishment is becoming narrow and significant drought stress is now almost inevitable. To moderate its extent andmagnitude, rainfall in excess of 120% of average (about a 1 in 5 chance) is needed over the next 10-12 weeks.

RainfallHigh pressure dominated synoptic patterns throughoutJanuary. A few frontal incursions brought significantrainfall, e.g. on the 10th when Capel Curig registered62mm. Thereafter, most areas reported remarkedly dryconditions – with rainfall totals of <5mm in parts of centralsouthern England over sequences of 30, or more, days.Correspondingly, January rainfall totals were <40% acrossmuch of the country, with totals below 20% in a few areas(e.g. the Isle of Wight). More importantly, the last threemonths have been dry in all regions. For E&W the Nov-Jan period (on average, the wettest 3-month sequence inthe year) was the 2nd driest since 1976 (with some easternand southern catchments reporting only around 50% ofaverage). Last year, the same period was only marginallywetter and, taken together, they closely match 1962-64 asthe driest successive Nov-Jan periods since 1932-34. Inmany catchments the drought began during November2004 and rainfall deficiencies over the last 15-monthsexceed 30% in the most severely affected areas – a zonefrom east Dorset to northern Kent (and extending into theThames basin). Substantially drier 15-month periods haverecorded for E&W (e.g. in 1975/76 & 1933/34) but adistinguishing feature of the current drought is thedisproportionate contribution of the winter months to theoverall rainfall deficiency. Correspondingly, the impacton reservoir and aquifer replenishment, and on river flows,has been severe in many areas.

River FlowModest spate conditions characterised many responsiverivers early in January but sustained and steep recessionsbetter typified flow patterns during the month. Withbaseflows very moderate and field drains running weaklyif at all, flows in many rivers (including the Trent, Cree,Luss and Faughan) were approaching seasonal minimaby early February. January runoff totals were well belowaverage in almost all index rivers. In northern Scotland,the Naver reported its lowest January runoff on recordbut depressed runoff totals were most widespread insouthern Britain – below 50% of average in manycatchments with river flows more typical of mid summerin the worst affected areas. Importantly however, only ina few cases (e.g. the Mimram and Soar) was runoff lessthan in January 1997. More revealing in terms of drought

severity are the accumulated runoff totals since October2004. Across much of E&W (parts of Northern Irelandalso) 15-month runoff accumulations are notably low, andunprecedented in this timeframe for a significant minorityof southern rivers (from the Medway to the Kenwyn; alsothe Soar in the Midlands). For the Sussex Ouse, runoffsince the beginning of 2005 matches 1975/76 as the lowestfor any 13-month sequence in a 46-year record. Particularconcern focuses on spring-fed streams and rivers whereflows, in some cases, have been below average for morethan 30 months and should, in a typical year, beapproaching their maximum flow. In the absence of asharp, and much belated, seasonal recovery, verydepressed flows are likely in the late summer (with a muchdiminished stream network).

GroundwaterRainfall to most outcrop areas was only 30-40% of averagein January and, with soil moisture deficits yet to besatisfied across much of the English Lowlands, infiltrationrates were again very modest (minimal in many easternareas). As a consequence, the late autumn seasonalrecoveries in groundwater levels, evident in many westernand northern index boreholes, have faltered – with declinesat some sites reporting late in January (e.g. at WestWoodyates and Alstonfield). Of particular concern is thecontinuing failure of any significant seasonal recovery tobe initiated in substantial parts of the central and easternChalk outcrop. Horizontal groundwater level hydrographtraces for some index boreholes confirm that, thus far,winter recharge only just matches natural outflows fromthe aquifer; at other index sites (in both the Chalk andPermo-Triassic sandstones) recessions have continuedfrom 2005. Levels in many Chalk boreholes are seasonallydepressed – closely approaching the long term minimumat Stonor, in the Chilterns – but overall storage in theChalk is greater than in early 1997 and early 1992 (bothvery severe groundwater drought winters). Groundwaterlevels in most Limestone and Permo-Triassic outcrops areseasonally low but above drought minima; Morris Dancersin the East Midlands is an exception – reporting its 2nd

lowest January level on record. As usual, acceleratingevaporation rates are expected to curtail lowland rechargeduring (or before) the late-spring; this underlines theimportance of sustained rainfall in the interim.

2

Area Rainfall Jan 2006 Nov 05-Jan 06 Aug 05-Jan 06 Feb 05-Jan 06 Nov 04-Jan 06RP RP RP RP

England mm 33 189 441 788 977& Wales % 37 68 5-15 85 2-5 87 5-10 83 10-20

North West mm 62 255 638 1066 1416% 52 69 5-15 88 2-5 88 2-5 89 5-10

Northumbrian mm 38 184 448 874 1065% 45 73 5-10 92 2-5 101 2-5 95 2-5

Severn Trent mm 21 142 352 669 795% 29 64 5-15 84 2-5 87 5-10 80 10-20

Yorkshire mm 29 159 390 751 906% 37 65 5-15 84 2-5 90 2-5 84 5-15

Anglian mm 17 90 279 535 631% 33 55 20-30 87 2-5 89 2-5 82 10-20

Thames mm 21 132 315 551 667% 32 65 5-15 82 2-5 79 10-20 74 30-45

Southern mm 27 141 335 593 730% 33 57 10-20 73 5-15 76 10-20 71 50-80

Wessex mm 23 184 390 719 884% 26 68 5-10 80 5-10 84 5-10 79 10-20

South West mm 46 316 608 1040 1305% 33 77 2-5 86 2-5 87 5-10 82 10-20

Welsh mm 56 332 701 1178 1506% 39 75 5-10 87 2-5 88 5-10 84 5-15

Scotland mm 106 374 831 1444 1997% 68 80 5-10 93 2-5 98 2-5 103 2-5

Highland mm 134 495 1056 1798 2597% 74 87 2-5 99 2-5 103 2-5 112 5-15

North East mm 46 272 543 1001 1285% 45 89 2-5 92 2-5 97 2-5 96 2-5

Tay mm 91 321 686 1234 1633% 62 79 2-5 90 2-5 96 2-5 96 2-5

Forth mm 69 235 561 1077 1446% 58 67 10-20 83 5-10 94 2-5 97 2-5

Tweed mm 52 206 517 958 1202% 51 70 5-15 90 2-5 96 2-5 93 2-5

Solway mm 102 321 766 1304 1748% 67 72 5-10 88 2-5 91 2-5 93 2-5

Clyde mm 140 406 955 1641 2305% 74 73 5-15 88 2-5 94 2-5 100 <2

Northern mm 47 234 549 981 1285Ireland % 40 70 5-10 85 2-5 89 2-5 90 2-5

Rainfall accumulations and return period estimates

% = percentage of 1961-90 average RP = Return periodThe monthly rainfall figures* provided by the Met Office (National Climate Information Centre) are Crown Copyright and may not be passed on to, orpublished by, any unauthorised person or organisation. All monthly totals since August 2005 are provisional (see page 12). 1961-2003 regionalmonthly totals were revised by the Met Office in 2004. Most of the return period estimates are based on tables provided by the Met Office (see Tabony,R. C., 1977, The variability of long duration rainfall over Great Britain, Scientific Paper No. 37) and relate to the specified span of months only (returnperiods may be up to an order of magnitude less if n-month periods beginning in any month are considered); RP estimates for Northern Ireland are basedon the tables for north-west England. The tables reflect rainfall over the period 1911-70 and assume a stable climate. Artifacts, in the Scottish rainfallseries in particular, can exaggerate the relative wetness of the recent past. *See page 12.

Rainfall . . . Rainfall . . .

3

74%

71%

82%80%

84%

84%

82%

79%

89%

90%

93%

93%

96%

95%

100%

96%

97%

112%

The persistance of a high pressure over the British Isles was a primary factor in the very moderate Nov-Jan rainfall acrossthe UK; provisional data rank it the 5th driest such period since 1964. Rainfall deficiencies were especially notable for theAnglian region - the 2nd driest (after 1988/89) in the last 52 years. The 15-month deficiencies emphasise the regionalfocus of thecurrent drought but also demonstrate how the region experiencing significant drought conditions has extendedthrough the winter.

Rainfall accumulation maps

Rainfall . . . Rainfall . . .

November 2005 - January 2006 November 2004 - January 2006

Key

00% Percentage ofNormal range

Below average

Substantially below average

Exceptionally low rainfall

Very wet

Substantially aboveaverage

Above average

1961-90 average

55%64%

69% 65%

65%

73%

57%

67%

70%

75%

70%

77%

68%

73%

79%

72%

87%

89%

4

J

!(

!(

!(!(

!(

!(

!(

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!(!(

!(

!(

!(!(

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!(

!( !(!( !(

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!(

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!(

!(

!( !(

!(

!(

!(

!(

!(

!(

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!(

!(

!(!(

!(!( !(

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!(

33%

20

40

45

31

40

38

49

494140

35

48 41

4934

51

1646

50

39

44

34

44

50

51

65

59

65

53

69

66

78

73

66

54

53

4145

54

54

65

65

49

69

51

88

88

66

79

77

7585

71

74

70

78

83

Naver

Ness Spey

Ewe

Dee

TayNevis

Tweed

Luss

Carron

Earn

WhiteadderClyde

Cree

SouthTyne

Derwent

Wharfe

Leven

Eden

Lune

Dee DoveTrent

Lud

Soar

Witham

GreatOuse

LittleOuse

GreatStour

Stour

Itchen

Lambourn

TeifiYscir

Cynon

Teme

Severn

Coln

ToneTawExe

Avon

Ouse

Thames

Mimram

Colne

WarlegganKenwyn

Bush

AnnacloyCamowen

Lee

KennetMedway

AvonWye

Ribble

Nith

Key

% of long-term average(record figure when circled)

!( Exceptionally low flow

!( Notably low flow

!( Exceptionally high flow

!( Below normal

!( Normal range

!( Notably high flow

!( Above normal

J25

Based on ranking of the monthly flow*

River flow . . . River flow . . .

River flows*Comparisons based on percentage flows alone can be misleading. A given percentage flow can represent extreme droughtconditions in permeable catchments where flow patterns are relatively stable but be well within the normal range in imper-meable catchments where the natural variation in flows is much greater. Note: the period of record on which these percent-ages are based varies from station to station. Percentages may be omitted where flows are under review.

January 2006

November 2004 - January 2006

J

J

J

J

J

!(

!(

!(!(

!(

!(

!(

!(!(

!(

!(

!(

!(

!(!(

!(!(!(

!(

!( !(!( !(

!(

!(

!(!(!(

!(

!(

!( !(

!(

!(

!(

!(

!(

!(

!(

!(!(

!(

!(

!(!(

!(!( !(

!(!(

!(!(

!(

!(

!(

!(

!(

!(

53%

37%

67%

59%

31%

71

71

78

71

67

71

7479

74

6357

73

81

5658

60 59

73

61

75

61

68

81

57

76

87

85

80

91

89

70

85

8682

85

83

87

76

86

75

90

98

93

91

110

107

102

102

106

107

115

113125

Naver

Ness Spey

Ewe

Dee

TayNevis

Tweed

Luss

Carron

Earn

WhiteadderClyde

Cree

SouthTyne

Derwent

Wharfe

Leven

Eden

Lune

Dee DoveTrent

Lud

Soar

Witham

GreatOuse

LittleOuse

GreatStour

Stour

Itchen

Lambourn

TeifiYscir

Cynon

Teme

Severn

Coln

ToneTawExe

Avon

Ouse

Thames

Mimram

Colne

WarlegganKenwyn

Bush

AnnacloyCamowen

Lee

KennetMedway

AvonWye

Ribble

Nith

5

500

1000

2000

5000

10000

20000

50000

JanFeb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

m3 s-1

Gau

ged

Dis

char

ge

Great Britain 2005/2006

Station No: 600021 Daily mean flows+ extreme daily flows (1961 to 2006)

200

500

1000

2000

5000

10000

20000


m3 s-1

Gau

ged

Dis

char

ge

England and Wales 2005/2006


200

500

1000

2000

5000

10000

20000

50000


m3 s-1

Gau

ged

Dis

char

ge

Scotland 2005/2006


20

50

100

200

500

1000

2000

5000


m3 s-1

Gau

ged

Dis

char

ge

Northern Ireland 2005/2006


1

2

5

10

20

50

100

200

500


m3 s-1

Gau

ged

Dis

char

ge

Ewe at Poolewe 2005/2006


10

20

50

100

200

500

1000

2000


m3 s-1

Gau

ged

Dis

char

ge

Tay at Ballathie 2005/2006


5

10

20

50

100

200

500

1000


m3 s-1

Gau

ged

Dis

char

ge

Clyde at Daldowie 2005/2006


2

5

10

20

50

100

200


m3 s-1

Gau

ged

Dis

char

ge

Derwent at Buttercrambe 2005/2006


0.2

0.5

1

2

5

10

20

50

100

200


m3 s-1

Gau

ged

Dis

char

ge

Camowen at Camowen Terrace 2005/2006


0.2

0.5

1

2

5

10

20

50

100


m3 s-1

Gau

ged

Dis

char

ge

Bush at Seneirl Bridge 2005/2006


The river flow hydrographs show the daily mean flows together with the maximum and minimum daily flows prior toFebruary 2005 (shown by the shaded areas). Daily flows falling outside the maximum/minimum range are indicated wherethe bold trace enters the shaded areas.

RivRivRivRivRiver floer floer floer floer flow hw hw hw hw hydrydrydrydrydrooooogrgrgrgrgraphsaphsaphsaphsaphs


6

5

10

20

50

100

200

500

1000


m3 s-1

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ged

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char

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Eden at Sheepmount 2005/2006


10

20

50

100

200

500

1000


m3 s-1

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ged

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char

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Trent at Colwick 2005/2006


5

10

20

50

100

200

500

1000


m3 s-1

Gau

ged

Dis

char

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Severn at Bewdley 2005/2006


0.05

0.1

0.2

0.5

1

2

5


m3 s-1

Gau

ged

Dis

char

ge

Lud at Louth 2005/2006


0.5

1

2

5

10

20

50

100

200

500


m3 s-1

Gau

ged

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char

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Teifi at Glan Teifi 2005/2006


0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50


m3 s-1

Gau

ged

Dis

char

ge

Colne at Lexden 2005/2006


0.2

0.5

1

2

5

10

20

50

100

200


m3 s-1

Gau

ged

Dis

char

ge

Cynon at Abercynon 2005/2006


5

10

20

50

100

200

500

1000


m3 s-1

Nat

ural

ised

Dis

char

ge

Thames at Kingston 2005/2006


1

2

5

10

20

50

100

200


m3 s-1

Gau

ged

Dis

char

ge

Stour at Throop 2005/2006


2

5

10

20

50


m3 s-1

Gau

ged

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char

ge

Itchen at Highbridge+Allbrook 2005/2006


River %lta Rankb) Spey (Boat o’Brig) 125 51/53

Soar 53 1/34Thames(naturalised) 59 10/122Mole 53 1/29Medway 31 1/42Ouse (Gold Bridge) 37 1/39Wallington 42 2/48

River %lta RankTest 65 2/47Stour (Throop) 59 1/32Piddle 61 2/40Exe 71 2/49Otter 70 1/43Kenwyn 67 1/37L Bann 76 1/25

NotabNotabNotabNotabNotable rle rle rle rle runoff accumulaunoff accumulaunoff accumulaunoff accumulaunoff accumulations (a) Notions (a) Notions (a) Notions (a) Notions (a) Novvvvvember 2005- Januarember 2005- Januarember 2005- Januarember 2005- Januarember 2005- January 2006,y 2006,y 2006,y 2006,y 2006, (b) No (b) No (b) No (b) No (b) Novvvvvember 2004 - Januarember 2004 - Januarember 2004 - Januarember 2004 - Januarember 2004 - January 2006y 2006y 2006y 2006y 2006

River %lta Ranka) Forth 63 2/25

Wharfe 65 3/51Dover Beck 55 4/31Lee(naturalised) 39 14/121Mimram 47 3/52Lambourn 56 3/44Cree 70 4/43Luss 65 2/27Faughan 67 1/30


lta = long term averageRank 1 = lowest on record

7

Dalton Holme

Well No: SE94/5 Aquifer: Chalk+ extremes & mean monthly levels (1889-2002)

2003 2004 2005 2006

10.0

15.0

20.0

Wat

er L

evel

( m

OD

)

10.0

15.0

20.0

Mea

surin

g le

vel :

34

.50

Washpit Farm

Well No: TF81/2A Aquifer: Chalk+ extremes & mean monthly levels (1950-2002)

2003 2004 2005 200640.0

45.0

50.0

Wat

er L

evel

( m

OD

)

40.0

45.0

50.0

Mea

surin

g le

vel :

80

.19

Stonor Park

Well No: SU78/45A Aquifer: Chalk+ extremes & mean monthly levels (1961-2002)

2003 2004 2005 200660.0

70.0

80.0

90.0

Wat

er L

evel

( m

OD

)

60.0

70.0

80.0

90.0

Mea

surin

g le

vel :

121

.29

Dial Farm

Well No: TM15/112 Aquifer: Chalk+ extremes & mean monthly levels (1968-2002)

2003 2004 2005 2006

25.0

26.0

Wat

er L

evel

( m

OD

)

25.0

26.0

Mea

surin

g le

vel :

64

.60

Rockley

Well No: SU17/57 Aquifer: Chalk+ extremes & mean monthly levels (1933-2002)

2003 2004 2005 2006

130.0

135.0

140.0

145.0

Wat

er L

evel

( m

OD

)

130.0

135.0

140.0

145.0

Mea

surin

g le

vel :

146

.57

Little Bucket Farm

Well No: TR14/9 Aquifer: Chalk+ extremes & mean monthly levels (1971-2002)

2003 2004 2005 2006

60.0

70.0

80.0

Wat

er L

evel

( m

OD

)

60.0

70.0

80.0

Mea

surin

g le

vel :

87

.33

West Woodyates Manor

Well No: SU01/5B Aquifer: Chalk+ extremes & mean monthly levels (1942-2002)

2003 2004 2005 2006

80.0

100.0

Wat

er L

evel

( m

OD

)

80.0

100.0

Mea

surin

g le

vel :

110

.88

Chilgrove House

Well No: SU81/1 Aquifer: Chalk+ extremes & mean monthly levels (1836-2002)

2003 2004 2005 2006

40.0

60.0

Wat

er L

evel

( m

OD

)

40.0

60.0

Mea

surin

g le

vel :

77

.18

Killyglen

Well No: ID30/1 Aquifer: Chalk+ extremes & mean monthly levels (1985-2002)

2003 2004 2005 2006

115.0

120.0

Wat

er L

evel

( m

OD

)

115.0

120.0

Mea

surin

g le

vel :

139

.23

New Red Lion

Well No: TF03/37 Aquifer: Lincolnshire Limestone+ extremes & mean monthly levels (1964-2002)

2003 2004 2005 2006

10.0

20.0

Wat

er L

evel

( m

OD

)

10.0

20.0

Mea

surin

g le

vel :

33

.45

Groundwater levels normally rise and fall with the seasons, reaching a peak in the spring following replenishment through thewinter (when evaporation losses are low and soil moist). They decline through the summer and early autumn. This seasonalvariation is much reduced when the aquifer is confined below overlying impermeable strata. The monthly max., min. andmean levels are displayed in a similar style to the river flow hydrographs. Note that most groundwater levels are not measuredcontinuously – the latest recorded levels are listed overleaf.

Groundwater . . . Groundwater

8

Ampney Crucis

Well No: SP00/62 Aquifer: Middle Jurassic+ extremes & mean monthly levels (1958-2002)

2003 2004 2005 2006

98.0

100.0

102.0

Wat

er L

evel

( m

OD

)

98.0

100.0

102.0

Mea

surin

g le

vel :

109

.54

Newbridge

Well No: NX97/2 Aquifer: Permo-Triassic sandstone+ extremes & mean monthly levels (1993-2002)

2003 2004 2005 2006

9.0

10.0

11.0

12.0

Wat

er L

evel

( m

OD

)

9.0

10.0

11.0

12.0

Mea

surin

g le

vel :

-99

9.00

Skirwith

Well No: NY63/2 Aquifer: Permo-Triassic sandstone+ extremes & mean monthly levels (1978-2002)

2003 2004 2005 2006

130.0

131.0

Wat

er L

evel

( m

OD

)

130.0

131.0

Mea

surin

g le

vel :

133

.25

Brick House Farm

Well No: SE44/80 Aquifer: Magnesian Limestone+ extremes & mean monthly levels (1979-2002)

2003 2004 2005 200610.0

12.0

14.0

16.0

Wat

er L

evel

( m

OD

)

10.0

12.0

14.0

16.0

Mea

surin

g le

vel :

53

.34

Llanfair DC

Well No: SJ15/13 Aquifer: Permo-Triassic sandstone+ extremes & mean monthly levels (1972-2002)

2003 2004 2005 2006

79.0

80.0

81.0

Wat

er L

evel

( m

OD

)

79.0

80.0

81.0

Mea

surin

g le

vel :

83

.08

Morris Dancers

Well No: SK67/17 Aquifer: Permo-Triassic sandstone+ extremes & mean monthly levels (1969-2002)

2003 2004 2005 2006

32.0

33.0

Wat

er L

evel

( m

OD

)

32.0

33.0

Mea

surin

g le

vel :

54

.83

Heathlanes

Well No: SJ62/112 Aquifer: Permo-Triassic sandstone+ extremes & mean monthly levels (1971-2002)

2003 2004 2005 2006

62.0

64.0

Wat

er L

evel

( m

OD

)

62.0

64.0

Mea

surin

g le

vel :

68

.61

Nuttalls Farm

Well No: SK00/41 Aquifer: Permo-Triassic sandstone+ extremes & mean monthly levels (1974-2002)

2003 2004 2005 2006

128.0

130.0

132.0

Wat

er L

evel

( m

OD

)

128.0

130.0

132.0

Mea

surin

g le

vel :

141

.78

Bussels No.7a

Well No: SX99/37B Aquifer: Permo-Triassic sandstone+ extremes & mean monthly levels (1971-2002)

2003 2004 2005 2006

23.0

24.0

25.0

Wat

er L

evel

( m

OD

)

23.0

24.0

25.0

Mea

surin

g le

vel :

26

.97

Alstonfield

Well No: SK15/16 Aquifer: Carboniferous Limestone+ extremes & mean monthly levels (1974-2002)

2003 2004 2005 2006

180.0

200.0

Wat

er L

evel

( m

OD

)

180.0

200.0

Mea

surin

g le

vel :

280

.25

Groundwater . . . Groundwater

Borehole Level Date Jan. av.Dalton Holme 12.74 16/01 17.19Washpit Farm 42.90 06/02 43.79Stonor Park 62.85 31/01 73.67Dial Farm 25.06 09/01 25.50Rockley 134.99 31/01 136.27Little Bucket Farm 61.50 31/01 68.28West Woodyates 85.18 31/01 91.64

Borehole Level Date Jan. av.Chilgrove House 46.62 01/02 56.17Killyglen 115.17 30/01 116.21New Red Lion 12.63 30/01 14.86Ampney Crucis 101.51 31/01 102.33Newbridge 10.25 01/02 10.77Skirwith 130.06 19/01 130.44Brick House Farm 11.27 23/01 12.89

GrGrGrGrGroundwoundwoundwoundwoundwaaaaater leter leter leter leter levvvvvels Januarels Januarels Januarels Januarels January / Fy / Fy / Fy / Fy / Febrebrebrebrebruaruaruaruaruary 2006y 2006y 2006y 2006y 2006

Levels in metres above Ordnance Datum

Borehole Level Date Jan. av.Llanfair DC 79.92 15/12 79.97Morris Dancers 31.67 25/01 32.37Heathlanes 61.05 23/01 61.96Nuttalls Farm 128.72 11/01 129.51Bussels No.7a 24.08 25/01 24.12Alstonfield 189.20 11/01 198.79

9

!(

!(!(

!(

!(

!(!(

!(!(

!(!( !(!(!(

!(

!(

!(

!(

!(!(

!(

!(

!(

!(

!(!(

!(

!(

!(!(

!(

3/64

2/44

5/38

2/37

6/46

5/42

14/118

3/12

4/26

7/32

6/34

8/32

7/24

9/35

3/20

14/6140/17131/111

27/118

10/28

23/33

20/35

13/42

13/31

10/34

32/73

18/52

10/33

Key

Newbridge

SwanHouse

Skirwith

Killyglen

DaltonHome

Wetwang

Yew TreeFarm

LlanfairD.C.

NuttallsFarm

Weeford Flats New Red Lion

WashpitFarm

Alstonfield

Heathlanes

MorrisDancers

AmpneyCrucis Stonor

Park

TherfieldRectory

RedlandsHall

Dial Farm

LittleBucketFarm

ChilgroveHouse Westdean

No 3

ComptonHouse

AshtonFarm

WestWoodyatesManor

BusselsNo 7A

Rockley

LimeKilnWay

Aylesby

Monthly rank/Period of record(record figure when circled)J1/25

!( Exceptionally low levels!( Notably low levels

!( Exceptionally high levels

!( Significantly below average!( Normal range

!( Notably high levels

!( Significantly above average

Brick HouseFarm

Aquifer

Chalk

Jurassic limestones

Magnesian Limestone

Permo-Triassic sandstones

Groundwater levels - January 2006The rankings are based on a comparison between the average level in the featured month (but often only single readings areavailable) and the average level in each corresponding month on record. They need to be interpreted with caution especiallywhen groundwater levels are changing rapidly or when comparing wells with very different periods of record. Rankingsmay be omitted where they are considered misleading.Notes: i. The outcrop areas are coloured according to British Geological Survey conventions.

ii. Yew Tree Farm levels are now received quarterly.

Groundwater . . .Groundwater

10

1997 1998 1999 2000 2001 2002 2003 2004 2005−25

−20

−15

−10

−5

0

5

10

15

20

25

% d

evn.

from

198

8−20

05 m

onth

ly m

ean

Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan40

50

60

70

80

90

100

Per

cent

age

live

capa

city

1988−2005 mean1989/901995/961996/972005/06

Percentage live capacity of selected reservoirs at start of month

Area Reservoir Capacity (Ml) 20052005200520052005 2006 2006 2006 2006 2006 AAAAAvg.vg.vg.vg.vg. Min.Min.Min.Min.Min. YYYYYear*ear*ear*ear*ear*OctOctOctOctOct NoNoNoNoNovvvvv DecDecDecDecDec JanJanJanJanJan FebFebFebFebFeb FebFebFebFebFeb FebFebFebFebFeb of min.of min.of min.of min.of min.

North West N Command Zone ••••• 124929 52 74 90 82 89 92 63 1996Vyrnwy 55146 56 82 88 85 91 91 45 1996

Northumbrian Teesdale • 87936 73 85 91 93 94 91 51 1996Kielder (199175) (86) (98) (91) (92) (93) (94) (85) 1989

Severn Trent Clywedog 44922 70 82 82 86 87 87 62 1996Derwent Valley • 39525 55 75 86 92 93 93 15 1996

Yorkshire Washburn • 22035 57 69 79 92 85 88 34 1996Bradford supply • 41407 55 65 80 81 82 93 33 1996

Anglian Grafham (55490) (80) (79) (81) (79) (85) (86) (67) 1998Rutland (116580) (76) (73) (73) (72) (80) (85) (68) 1997

Thames London • 202406 65 65 80 87 92 89 70 1997Farmoor • 13822 98 100 99 98 93 92 72 2001

Southern Bewl 28170 44 39 36 34 37 82 37 2006Ardingly 4685 47 44 50 57 65 94 65 2006

Wessex Clatworthy 5364 53 55 92 99 100 94 62 1989Bristol WW • (38666) (47) (47) (59) (71) (76) (84) (58) 1992

South West Colliford 28540 45 46 51 56 60 83 52 1997Roadford 34500 53 57 63 68 69 81 30 1996Wimbleball 21320 61 62 73 77 84 89 59 1997Stithians 5205 41 43 64 74 83 87 38 1992

Welsh Celyn and Brenig • 131155 77 87 95 94 96 94 61 1996Brianne 62140 82 99 92 97 95 98 84 1997Big Five • 69762 54 75 87 97 97 93 67 1997Elan Valley • 99106 64 83 98 100 98 97 73 1996

Scotland(E) Edinburgh/Mid Lothian • 97639 72 80 94 93 95 93 72 1999East Lothian • 10206 66 72 93 93 100 97 68 1990

Scotland(W) Loch Katrine • 111363 81 95 88 82 94 93 85 2000Daer 22412 69 100 98 97 100 99 91 1997Loch Thom • 11840 87 87 100 100 100 98 90 2004

Northern Total+ • 67270 65 80 85 92 90 89 75 2002Ireland Silent Valley • 20634 64 82 92 99 94 82 46 2002() figures in parentheses relate to gross storage • • • • • denotes reservoir groups +excludes Lough Neagh *last occurrence - see footnote

Reservoirs . . . Reservoirs . . .

These plots are based on the England and Wales figures listed below.

Details of the individual reservoirs in each of the groupings listed above are available on request. The featured reservoirs may not be representative ofthe storage conditions across each region; this can be particularly important during droughts. The storage figures relate to the 1988-2006 period only(except for West of Scotland and Northern Ireland where data commence in the mid-1990’s). In some gravity-fed reservoirs (e.g. Clywedog) stocks arekept below capacity during the winter to provide scope for flood attenuation purposes.

Guide to the variation in overallreservoir stocks for England andWales

Comparison between overallreservoir stocks for England andWales in recent years

11

gauging station

groundwater index well

reservoir - individual

reservoir - group (general location only)

Chalk

Jurassic limestones

Permo-Triassic sandstones

Magnesian Limestone

Minor aquifers (including the Carboniferous

Limestone) have been omitted.

Dalton Holme

Wetwang

Washpit Farm

Therfield Rectory

Redlands Hall

Rockley

Little Bucket FarmComptonHouse

ChilgroveHouse

Westdean No.3Lime Kiln Way

Ashton Farm

WestWoodyatesManor

New Red Lion

AmpneyCrucis

Yew Tree Farm

Llanfair D.CMorris Dancers

WeefordFlats

Skirwith

Newbridge

Bussels No.7A

SwanHouse

BrickHouseFarm

Alstonfield

Heathlanes

NuttallsFarm

DialFarm

StonorPark

Aylesby

Vyrnwy

Kielder

Clywedog

Grafham Water

Rutland Water

Bewl WaterArdinglyClatworthy

Colliford

Roadford

Wimbleball

Stithians

LlynCelyn

Llyn Brenig

LlynBrianne

Farmoor

DaerLochBradan

Teesdale

Derwent Valley

East Lothian

Edin/Mid Lothian

NorthernCommand Zone

Bradford

Washburn

Elan Valley

BigFive

London

BristolWater

Loch Katrine

LochThom

Dee

Tay

Luss

Clyde Whiteadder

Tweed

Eden

South Tyne

Leven

Lune

Wharfe

Der

wen

t

Trent

Lud

Dee Dov

e

Witham

Soar

Severn

Teme

Yscir

Cynon

Coln

Great Ouse

Stri

ngsi

de

Little Ouse

Colne

Mimram

Lee

ThamesMole

BlackwaterKennet

Brue

Medway

Great

Stou

r

Ouse

Itch

en

StourPiddle

ToneExe

Taw

Kenwyn

Dart

Carron

Ewe

War

legg

an

Avon

Cree

Spey

Earn

Teifi

Naver

Dever

on

Lambourn

Nith

Ness

Wye

Otter

Tawe

Wallington

Lymington

Test

Tyne

Torne

Avon

Leven

DoverBeck

Nevis

Ribbl

e

Forth

Killyglen

Silent Valley

Annacloy

Camowen

BushLowerBannFaughan

Mourne

Lagan

Location map . . . Location map

12

National HydrologicalMonitoringProgramme

The National Hydrological Monitoring Programme(NHMP) was instigated in 1988 and is undertaken jointlyby the Centre for Ecology and Hydrology Wallingford(formerly the Institute of Hydrology - IH) and the BritishGeological Survey (BGS). Financial support for theproduction of the monthly Hydrological Summaries isprovided by the Department for Environment, Food andRural Affairs (Defra), the Environment Agency (EA), theScottish Environment Protection Agency (SEPA), theRivers Agency (RA) in Northern Ireland, and the Officeof Water Services (OFWAT).

Data SourcesRiver flow and groundwater level data are provided bythe Environment Agency, the Environment Agency Wales,the Scottish Environment Protection Agency and, forNorthern Ireland, the Rivers Agency and the Departmentof the Environment (NI). In all cases the data are subjectto revision following validation (flood and drought datain particular may be subject to significant revision).

Reservoir level information is provided by the WaterService Companies, the EA, Scottish Water and theNorthern Ireland Water Service.

The National River Flow Archive (maintained by CEHWallingford) and the National Groundwater Level Archive(maintained by BGS) provide the historical perspectivewithin which to examine contemporary hydrologicalconditions.

RainfallMost rainfall data are provided by the Met Office (seeopposite). To allow better spatial differentiation therainfall data for Britain are presented for the regionaldivisions of the precursor organisations of the EA andSEPA. Following the discontinuation of the Met Office’sCARP system in July 1998, the areal rainfall figures havebeen derived using several procedures, including initialestimates based on MORECS*. Recent figures have beenproduced by the Met Office, National Climate InformationCentre (NCIC), using a technique similar to CARP. Asignificant number of additional monthly raingauge totalsare provided by the EA and SEPA to help derive thecontemporary regional rainfalls. Revised monthly nationaland regional rainfall totals for the post-1960 period(together with revised 1961-90 averages) were madeavailable by the Met Office in 2004; these have beenadopted by the NHMP. As with all regional figures basedon limited raingauge networks the monthly tables andaccumulations (and the return periods associated withthem) should be regarded as a guide only.

*MORECS is the generic name for the Met Office servicesinvolving the routine calculation of evaporation and soilmoisture throughout Great Britain.

The Met OfficeFitzRoy RoadExeterDevonEX1 3PB

Tel.: 0870 900 0100Fax: 0870 900 5050E-mail: [email protected]

The National Hydrological Monitoring Programmedepends on the active cooperation of many data suppliers.This cooperation is gratefully acknowledged.

SubscriptionSubscription to the Hydrological Summaries costs £48 peryear. Orders should be addressed to:

Hydrological SummariesNational Water ArchiveCEH WallingfordMaclean BuildingCrowmarsh GiffordWallingfordOxfordshireOX10 8BB

Tel.: 01491 838800Fax: 01491 692424E-mail: [email protected]

Selected text and maps are available on the WWW athttp://www.nerc-wallingford.ac.uk/ih/nrfa/index.htmNavigate via Water Watch

Some of the features displayed in the maps contained inthis report are based on the Ordnance Survey BaseDataGB and 1:50,000 digital data (Licence no. GD03012G/01/97) and are included with the permission of HerMajesty’s Stationery Office. © Crown Copyright.Rainfall data supplied by the Met Office are also CrownCopyright. Unauthorised reproduction infringes CrownCopyright and may lead to prosecution.

© This document is copyright and may not be reproducedwithout the prior permission of the Natural EnvironmentResearch Council.

02/06

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