Hydrological Summary for the

General Indian Summer conditions characterised the first half of September but, thereafter, weather patterns were much more autumnal. September rainfall totals were considerably below average across most of the country. Correspondingly, reservoirs stocks generally followed a normal seasonal decline – but from elevated late summer levels in southern Britain. Early October stocks in some large Scottish impoundments (e.g. Loch Thom) were significantly below average but mostly very healthy elsewhere. For & Wales as a whole, stocks were the 4th highest in a 20-year series; reflecting abundant runoff in most gathering grounds over the last 12 months. September river flows were typical of the early autumn except in some spring-fed rivers where they remained close to seasonal maxima. The return to more normal soil moisture conditions in the early autumn saw groundwater level recessions re-established but levels in most index wells were considerably above the September average. The recent dry spell has moderated, but not eliminated, the enhanced risk of groundwater flooding in vulnerable parts of the Chalk outcrop this winter.

Rainfall sheltered eastern catchments in Scotland and Northern The high pressure, which dominated synoptic patterns Ireland. The exceptional summer runoff is clearly during the first half of September, receded in mid-month reflected in runoff accumulations for the May-Sept period. allowing frontal systems to bring significant rainfall to Many new period-of-record maxima were established in some areas, mostly in the western uplands; Lusa (Skye) a broad zone from the North-East to Devon; previous reported 46.4mm on the 15th and Capel Curig (N. Wales) maxima for the Gt Ouse and Warwickshire Avon were 55.6mm on the 24th (a day when several tornadoes were eclipsed by considerable margins in records of >70 years. reported in southern Britain, e.g. in Farnborough). Of The widespread extension in the range of recorded greater hydrological significance was a notable dry spell summer flows is well illustrated by the River Coln (in the which had extended beyond 30 days by mid-September. ) where flows remained above previous daily Some areas (e.g. in the Lower Severn basin) registered no maxima for three months until the end of September. measurable rainfall during this episode, and much of Longer term runoff totals remain outstanding in much of central England reported <5mm. This very settled Scotland where new water-year (Oct-Sept) runoff maxima interlude is reflected in the September rainfall totals. A were established from the Naver to the Nith. few isolated localities (e.g. in the northern Pennines) exceeded the monthly average but parts of eastern Scotland Groundwater th registered their 4 driest September in 35 years. Many Soil moisture deficits, which had largely been eliminated catchments in the English Lowlands reported less than half by the summer rainfall, were re-established through the monthly average rainfall – adding to a cluster of dry September and, by early October, were within the normal Septembers in England since the mid-1990s. As in August, range across most aquifer outcrop areas. Soil conditions particularly modest rainfall was reported for those areas are thus exercising a normal seasonal constraint on aquifer worst afflicted by the summer flooding. After record May- recharge. Correspondingly, infiltration in September was nd July rainfall, the Severn-Trent Region registered its 2 minimal and groundwater levels recessions have become lowest Aug-Sept rainfall in 16 years. Nonetheless, rainfall re-established except in the slowest responding aquifer totals – over timespans of 4-12 months remain well above units. Nonetheless, September groundwater levels were average. The Oct-Sept period was the 2nd wettest since generally above average; notably so in many outcrops of 1929/30 for England & Wales and unprecedented for the Jurassic Limestone (where September levels were still Scotland in a 94-yr series. rising at the confined New Red Lion well), and in the western and northern extremities of the Chalk. In the River Flows latter, despite recent recessions, new September maximum

September runoff patterns exhibited substantial regional levels were established at Aylesby and Rockley (in a series September 2007 differences and a strong geological influence was evident, from 1933). Levels were also seasonally very high at with clear contrasts between rivers draining impermeable Wash Pit Farm in Norfolk. Levels are still increasing in catchments and those sustained principally by many of the slow responding Permo-Triassic outcrops in groundwater. In the former, some moderate spates were the Midlands; a particularly brisk recovery has been registered around the 24th (e.g. in northern England) but registered at Nuttalls Farm since the early summer. Spatial lengthy recessions were more typical. Entering October, variations in soil moisture conditions are considerable but, flows in the responsive Annacloy (Northern Ireland) had in most outcrop areas, deficits are the equivalent of 6-10 fallen close to the monthly minimum. By contrast, in some weeks autumn rainfall. It is likely therefore that the winter spring-fed rivers (including the Coln and Lambourn) flows recharge season will commence with groundwater levels – although in recession – established new runoff maxima above the seasonal norm and, in the event of a wet winter, for September. Such rivers aside, September runoff was maximum groundwater levels could be notably high, generally well within the normal range, albeit low in some particularly in parts of the Chalk. Rainfall . . . Rainfall . . .

Rainfall accumulations and return period estimates Area Rainfall Sep 2007 Aug 07-Sep 07 May 07-Sep 07 Jan 07-Sep 07 Oct 06-Sls -lrt *psep 07 RP RP RP RP England mm 52 112 508 794 1152 & Wales % 67 72 5-10 147 50-80 126 15-25 127 30-45 North West mm 99 182 626 993 1519 % 85 80 2-5 133 10-20 118 5-10 125 20-30 Northumbrian mm 57 109 465 707 1002 % 77 69 5-10 134 10-20 114 5-10 116 5-10 Severn Trent mm 40 80 504 749 1026 % 62 60 5-10 163 >100 136 30-50 134 50-80 Yorkshire mm 47 91 496 741 1023 % 67 62 5-10 150 40-60 124 10-20 123 10-20 Anglian mm 33 86 412 578 764 % 65 81 2-5 161 >100 132 20-35 126 20-30 Thames mm 29 80 416 637 919 % 49 67 5-10 149 30-40 127 10-20 131 20-35 Southern mm 34 85 395 638 963 % 48 67 5-10 139 10-20 119 5-10 123 10-20 Wessex mm 35 87 458 738 1104 % 48 62 5-10 146 20-35 124 5-15 129 20-30 South West mm 50 138 566 1013 1493 % 54 77 2-5 143 20-30 126 10-20 125 15-25 Welsh mm 88 169 678 1130 1742 % 75 76 2-5 144 30-45 125 10-20 129 30-45 Scotland mm 98 244 619 1185 1884 % 68 93 2-5 117 5-10 119 10-20 128 >100 Highland mm 137 321 710 1444 2322 % 81 108 2-5 119 5-10 125 20-35 133 >100 North East mm 66 172 541 860 1260 % 71 94 2-5 135 20-30 119 5-15 122 20-30 Tay m m 48 165 576 1074 1712 % 39 75 2-5 124 5-10 120 5-15 133 70-100 Forth mm 55 174 519 959 1525 % 48 83 2-5 119 5-10 120 10-20 133 >100 Tweed mm 58 140 509 819 1224 % 63 77 2-5 128 5-15 115 5-10 122 15-25 Solway mm 82 206 612 1088 1759 % 57 78 2-5 115 2-5 111 2-5 122 20-30 Clyde mm 114 267 646 1324 2182 % 62 82 2-5 102 2-5 112 5-10 125 30-45 Northern mm 58 157 507 832 1227 Ireland % 58 80 2-5 123 5-10 109 2-5 112 5-10 % = percentage of 1961-90 average RP = Return period Important note:Figures in the above table may be quoted provided that their source is acknowledged. See page 12. Where appropriate, specific reference must be made to the uncertainties associated with the return period estimates. Generally, the return period estimates are based on tables provided by the Met Office* but those for Northern Ireland are based on the estimates for north-west England. The estimates relate to the specified region and span of months only (RPs may be an order of magnitude less if n-month periods beginning in any month are considered), they reflect rainfall variability over the period 1911-70 only, and assume a stable climate. (For further details see Tabony, R. C., 1977, The variability of long duration rainfall over Great Britain, Scientific Paper No. 37). The timespans featured do not purport to represent the critical periods for any particular water resource management zone and, normally, for hydrological or water resources assessments of drought severity, river flows and groundwater levels provide a better guide than return periods based on rainfall totals. *In some cases ranking positions of accumulated rainfalls are also considered. All monthly rainfall totals since May 2007 are provisional. 2 Rainfall . . . Rainfall . . .

Soil Moisture Deficit Rainfall September 2007 August - September Difference from 1961-1990 average % of 1971 - 2000 mm 2007 -60.0- -40.0 130 - 150

-39.9- -20.0 110 - 130 90 - 110 -19.9- 0.0 70 - 90 0.1- 20.0 60 - 70 50 - 60 20+ 35 - 50

© Crown Copyright

Key Key Rainfall 25% Percentage of 1961-90 average Rainfall 25% Percentage of 1961-90 average Exceptionally low rainfall Exceptionally low rainfall September 2007 Substantially below average October 2006 - Substantially below average Below average Below average Normal range September 2007 Normal range Above average 133% Above average 81% Substantially above average Substantially above average Very wet 71% 122% Very wet

39% 133%

48% 133%

62% 1125% 63% 122%

57% 122% 77% 116% 58% 112%

85% 67% 125% 123%

134% 62% 65% 126%

75% 129%

49% 131%

129% 48% 48% 123%

54% 125%

3 River flow . . . River flow . . .

J!(168 Naver May 2007 - September 2007 !(150 Ewe !(110 Spey !(141 Ness

Dee !(142 115 Nevis !( Tay

!(124 Earn !(102 !(87 Luss

109 Whiteadder 119 Naver !( !(177 !( Clyde !(121 Twee d 117 South !( 125 Nith Tyne Bush !( 112 Cree 187 Ewe Camowen !( !( !(143 !(159 !(147 Eden Leven Spey Ness 75 210 !( 208 !( !(119 !(121 Annacloy !( J Lune Carron Derwent 144 !( !(174 181 J Dee !(66 !( 167 !( Wharfe 105 Nevis Ribble !( Tay LudJ!(255 !(55 Trent Dee Dove 333 199 !( Earn 40 !(JWitham !( !(158 !(157 J Luss !(49 Little Ouse Severn Soar !(210 J 152 205 !( 66 Whiteadder !( !( Tem e 73 381 !( !( 303 Great Clyde 152 J 312 Avon !( Colne !( Yscir !( J Ouse !(53 !(155 Wye J 108 Teifi Coln Mimram 99 !( 213 !( 127 Cynon !( 234 !( Lee Twee d 150 !( South !( J !(99 Nith !(61 Tyne Lambourn !(163!(157 !(206 Bush J 113 Great Tha mes !(103 !( 69 Cree 75 Avo n 122 Kennet Stour Camowen !( 84 !( !( !( 221 161 Medway 92 !( !( Ton e !(120 Itchen Ouse !( 65 J !( Eden !(198 Exe 163 Leven Taw Stour !( 75 !(20 !( !(152 Warleggan Annacloy Lune Derwent !(152 Kenwyn 82 !( !(106 !(91 99 !( Wharfe Key Ribble % of long-term average Lud !(265 25 J (record figure when circled) Trent Dee Dove 163 87 !( !( Witham !( Exceptionally high flow !(112 !(84 Little Ouse Notably high flow Severn Soar !(81 !( 146 65 !( !( Above normal Tem e 107 !( !( 148 Great 38 105 Avo n !( Colne !( Yscir !( Ouse !(51 Wye 58 !( Normal range Teifi Coln 90 !( 63 Mimram!( 107 Lee Cynon !( !(319 !( !(53 J !( Below normal Lambourn !(217!(179 !(150 J !(65 !(86 Great !( Notably low flow Avo n !(145 Kennet Tha mes Stour Medway !(43 !(92 134 Itchen 73 Exceptionally low flow Ton e !( Ouse !( !( 51 !( Exe 131 Taw Stour !( Based on ranking of the monthly flow*

!(97 Warleggan !(92 Kenwyn September 2007

River flows *Comparisons based on percentage flows alone can be misleading. A given percentage flow can represent extreme drought conditions 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. 4 River flow . . . River flow . . .

Great Britain 2006/2007 England and Wales 2006/2007 50000 20000

10000 20000

5000 10000 -1 -1 s s 5000 3 2000 3 m m

1000

Gauged Discharge 2000 Gauged Discharge

500 1000

500 200 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 600021 Daily mean flows Station No: 600041 Daily mean flows + extreme daily flows (1961 to 2007) + extreme daily flows (1961 to 2007)

Scotland 2006/2007 Northern Ireland 2006/2007 50000 5000

20000 2000

10000 1000

5000 500 -1 -1 s s 3 3 m m 2000 200

Gauged Discharge 1000 Gauged Discharge 100

500 50

200 20 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 600061 Daily mean flows Station No: 600081 Daily mean flows + extreme daily flows (1961 to 2007) + extreme daily flows (1980 to 2007)

Ewe at Poolewe 2006/2007 Tay at Ballathie 2006/2007 500 2000

200 1000

100 500

50 200 -1 -1 s s 20 3 3 m 100 m 10

Gauged Discharge Gauged Discharge 50 5

2 20

1 10 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 094001 Daily mean flows Station No: 015006 Daily mean flows + extreme daily flows (1970 to 2007) + extreme daily flows (1952 to 2007)

Clyde at Daldowie 2006/2007 Derwent at Buttercrambe 2006/2007 1000 200

500 100

200 50

100 -1 -1 s s 3 20 3 50 m m 10

Gauged Discharge 20 Gauged Discharge 5 10

5 2 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 084013 Daily mean flows Station No: 027041 Daily mean flows + extreme daily flows (1963 to 2007) + extreme daily flows (1973 to 2007)

Camowen at Camowen Terrace 2006/2007 Bush at Seneirl Bridge 2006/2007 200 100

100 50 50 20 20 10 10 -1 -1

s 5 s 3 3

5 m m

2 2 Gauged Discharge Gauged Discharge 1 1

0.5 0.5

0.2 0.2 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 201005 Daily mean flows Station No: 204001 Daily mean flows + extreme daily flows (1972 to 2007) + extreme daily flows (1972 to 2007)

River flow hydrographs The river flow hydrographs show the daily mean flows together with the maximum and minimum daily flows prior to October 2006 (shown by the shaded areas). Daily flows falling outside the maximum/minimum range are indicated where the bold trace enters the shaded areas.

5 River flow . . . River flow . . .

Eden at Sheepmount 2006/2007 Trent at Colwick 2006/2007 2000 1000

1000 500 500

200 200 -1 -1 s s 100 3 100 3 m m 50 50 Gauged Discharge Gauged Discharge 20 20 10

5 10 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 076007 Daily mean flows Station No: 028009 Daily mean flows + extreme daily flows (1967 to 2007) + extreme daily flows (1958 to 2007)

Severn at Bewdley 2006/2007 Lud at Louth 2006/2007 1000 10

500 5

200 2

100 1 -1 -1 s s 3 3

50 m 0.5 m

Gauged Discharge 20 Gauged Discharge 0.2

10 0.1

5 0.05 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 054001 Daily mean flows Station No: 029003 Daily mean flows + extreme daily flows (1921 to 2007) + extreme daily flows (1968 to 2007)

Teifi at Glan Teifi 2006/2007 Colne at Lexden 2006/2007 500 50

200 20 10 100 5 50 2

20 -1 -1 s s 3 1 3 m m 10 0.5 5

Gauged Discharge Gauged Discharge 0.2 2 0.1

1 0.05

0.5 0.02 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 062001 Daily mean flows Station No: 037005 Daily mean flows + extreme daily flows (1959 to 2007) + extreme daily flows (1959 to 2007)

Cynon at Abercynon 2006/2007 Thames at Kingston 2006/2007 200 1000

100 500 50

200 20

10 100 -1 -1 s s 3 3

5 m m 50

2 Gauged Discharge

Naturalised Discharge 20 1

0.5 10

0.2 5 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 057004 Daily mean flows Station No: 039001 Daily mean flows + extreme daily flows (1957 to 2007) + extreme daily flows (1883 to 2007)

Stour at Throop 2006/2007 Itchen at Highbridge+Allbrook 2006/2007 200 50

100

50 20

20 -1 -1 s s 3 10 3 10 m m

Gauged Discharge 5 Gauged Discharge 5

2

1 2 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Station No: 043007 Daily mean flows Station No: 042010 Daily mean flows + extreme daily flows (1973 to 2007) + extreme daily flows (1958 to 2007)

Notable runoff accumulations (a) Aug 2007 - Sep 2007, (b) May 2007 - Sep 2007, (c) Oct 2006 - Sep 2007 River %lta Rank River %lta Rank River %lta Rank a) Dover Beck 214 31/32 b) Leven (Leven Br) 210 47/47 c) Earn 135 59/59 Lud 323 40/40 Trent 199 49/49 Tweed (Boleside) 125 46/46 Stringside 350 42/42 Ouse (Bedford) 303 75/75 Dart 144 49/49 Thames (nat) 218 122/125 Blackwater 158 54/55 Dee (Manley Hall) 137 70/70 Kennet 191 46/46 Taw 221 49/49 Eden 139 40/40 Lambourn 221 45/45 Avon (Evesham) 312 71/71 Nith 132 50/50 Coln 381 44/44 Annacloy 208 26/28 Naver 151 30/30 Itchen 139 49/49 lta = long term average Avon (Amesbury) 156 43/43 6 Rank 1 = lowest on record Ewe 181 36/37 Groundwater . . . Groundwater

Dalton Holme Washpit Farm 50.0 50.0

20.0 20.0

45.0 45.0 15.0 15.0 Water Level ( mOD ) Water Level ( mOD ) 10.0 10.0 Measuring level : 34.50 Measuring level : 80.19 40.0 40.0 2004 2005 2006 2007 2004 2005 2006 2007 Well No: SE94/5 Aquifer: Chalk Well No: TF81/2A Aquifer: Chalk + extremes & mean monthly levels (1889-2003) + extremes & mean monthly levels (1950-2003)

Stonor Park Dial Farm 90.0 90.0 26.0 26.0 80.0 80.0

70.0 70.0 25.0 25.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 64.60 Measuring level : 121.29 60.0 60.0 2004 2005 2006 2007 2004 2005 2006 2007 Well No: SU78/45A Aquifer: Chalk Well No: TM15/112 Aquifer: Chalk + extremes & mean monthly levels (1961-2003) + extremes & mean monthly levels (1968-2003)

Rockley Well House Inn 145.0 145.0

100.0 100.0 140.0 140.0

135.0 135.0 90.0 90.0 Water Level ( mOD ) Water Level ( mOD )

130.0 130.0 Measuring level : 146.57 Measuring level : 132.27

2004 2005 2006 2007 2004 2005 2006 2007 Well No: SU17/57 Aquifer: Chalk Well No: TQ25/13 Aquifer: Chalk + extremes & mean monthly levels (1933-2003) + extremes & mean monthly levels (1942-2003)

West Woodyates Manor Chilgrove House

100.0 100.0 60.0 60.0

80.0 80.0 40.0 40.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 77.18 Measuring level : 110.88

2004 2005 2006 2007 2004 2005 2006 2007 Well No: SU01/5B Aquifer: Chalk Well No: SU81/1 Aquifer: Chalk + extremes & mean monthly levels (1942-2003) + extremes & mean monthly levels (1836-2003)

Killyglen New Red Lion 120.0 120.0 20.0 20.0

115.0 115.0 10.0 10.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 33.45 Measuring level : 139.23

2004 2005 2006 2007 2004 2005 2006 2007 Well No: ID30/1 Aquifer: Chalk Well No: TF03/37 Aquifer: Lincolnshire Limestone + extremes & mean monthly levels (1985-2003) + extremes & mean monthly levels (1964-2003)

Groundwater levels normally rise and fall with the seasons, reaching a peak in the spring following replenishment through the winter (when evaporation losses are low and soil moist). They decline through the summer and early autumn. This seasonal variation is much reduced when the aquifer is confined below overlying impermeable strata. The monthly mean and the highest and lowest levels recorded for each month are displayed in a similar style to the river flow hydrographs. Note that most groundwater levels are not measured continuously – the latest recorded levels are listed overleaf.

7 Groundwater . . . Groundwater

Ampney Crucis Newbridge 12.0 12.0

102.0 102.0 11.0 11.0

100.0 100.0 10.0 10.0

Water Level ( mOD ) 98.0 98.0 Water Level ( mOD ) Measuring level : 109.54 9.0 9.0 Measuring level : -999.00

2004 2005 2006 2007 2004 2005 2006 2007 Well No: SP00/62 Aquifer: Middle Jurassic Well No: NX97/2 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1958-2003) + extremes & mean monthly levels (1993-2003)

Skirwith Swan House 90.0 90.0

131.0 131.0 85.0 85.0

130.0 130.0 80.0 80.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 94.90 Measuring level : 133.25

2004 2005 2006 2007 2004 2005 2006 2007 Well No: NY63/2 Aquifer: Permo-Triassic sandstone Well No: NZ21/29 Aquifer: Magnesian Limestone + extremes & mean monthly levels (1978-2003) + extremes & mean monthly levels (1969-2003)

Brick House Farm Llanfair DC 81.0 81.0 16.0 16.0

14.0 14.0 80.0 80.0

12.0 12.0 79.0 79.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 53.34 Measuring level : 83.08 10.0 10.0 2004 2005 2006 2007 2004 2005 2006 2007 Well No: SE44/80 Aquifer: Magnesian Limestone Well No: SJ15/13 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1979-2003) + extremes & mean monthly levels (1972-2003)

Heathlanes Weeford Flats

64.0 64.0 91.0 91.0

62.0 62.0 90.0 90.0

89.0 89.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 68.61 Measuring level : 96.21

2004 2005 2006 2007 2004 2005 2006 2007 Well No: SJ62/112 Aquifer: Permo-Triassic sandstone Well No: SK10/9 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1971-2003) + extremes & mean monthly levels (1966-2003)

Bussels No.7a Alstonfield

25.0 25.0

200.0 200.0 24.0 24.0

180.0 180.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 26.97 23.0 23.0 Measuring level : 280.25 2004 2005 2006 2007 2004 2005 2006 2007 Well No: SX99/37B Aquifer: Permo-Triassic sandstone Well No: SK15/16 Aquifer: Carboniferous Limestone + extremes & mean monthly levels (1971-2003) + extremes & mean monthly levels (1974-2003) Groundwater levels September / October 2007 Borehole Level Date Sep. av. Borehole Level Date Sep. av. Borehole Level Date Sep. av. Dalton Holme 21.14 07/09 15.42 Chilgrove House 44.46 30/09 40.73 Brick House Farm 13.11 26/09 12.23 Washpit Farm 46.40 02/10 43.98 Killyglen 113.59 30/09 114.33 Llanfair DC 79.93 15/09 79.55 Stonor Park 77.27 01/10 74.37 New Red Lion 17.64 21/09 11.60 Heathlanes 62.18 26/09 62.00 Dial Farm 25.49 07/09 25.55 Ampney Crucis 100.69 01/10 100.07 Weeford Flats 90.05 06/09 89.78 Rockley 135.41 01/10 131.00 Newbridge 9.44 05/10 9.51 Bussels No.7a 23.65 03/10 23.50 Well House Inn 93.68 01/10 94.00 Skirwith 130.40 30/09 130.07 Alstonfield 184.92 03/09 177.43 West Woodyates 81.96 30/09 72.88 Swan House 83.41 17/09 82.38 Levels in metres above Ordnance Datum 8 Groundwater . . .Groundwater

Key

Monthly rank/Period of record J1/25 (record figure when circled) !( Exceptionally high levels !( Notably high levels !( Significantly above average !( Normal range !( Significantly below average !( Notably low levels !( Exceptionally low levels

Aquifer

Newbridge !(8/1 5 Magnesian Limestone Killyglen 7/2 3 !( Swan House Permo-Triassic sandstones Skirwith !(26/ 28 !(23 /3 4 Jurassic limestones Wetwang Chalk !(35 /3 5 Brick J House !(22 /2 7 118/1191!( Fa rm Dalton Holme J!(29 /29 Alstonfield Aylesby !(32 /3 6 !(29 /3 2 Llanfair !(43 /4 4 Washpit D.C. 21/ 37 54 /5 7 !( Weeford !( Fa rm !(25 /39 Fl ats New Red Lion Heathlanes 24 /3 3 !( Dial Nuttalls Redlands Fa rm Hall Fa rm !(14 /3 5 Th erfie ld !(17 /4 3 Ampney Rectory !(47/ 11 9 Crucis !(42 /4 7 Stonor !(28/4 6 Par k Rockley 75 /75 !( Well J 27/6 4 21 /3 9 !( House Littl e West !(Ti lshead Inn 25 /3 5 Bucket Lime !( Woodyates Compton Chilgrove Fa rm Kiln Manor 59 /6 1 House House Houndean Bussel s Way !( 105/112!(153/171!( !(19/ 30 17/ 38 No 7A 29 /3 5 !( 36/ 64 !( !( !( Westdean No 3 Ashton Farm

Groundwater levels - September 2007 The rankings are based on a comparison between the average level in the featured month (but often only single readings are available) and the average level in each corresponding month on record. They need to be interpreted with caution especially when groundwater levels are changing rapidly or when comparing wells with very different periods of record. Rankings may be omitted where they are considered misleading. Notes: i. The outcrop areas are coloured according to British Geological Survey conventions. 9 Reservoirs . . . Reservoirs . . .

Guide to the variation in overall Comparison between overall reservoir stocks for England and reservoir stocks for England and Wales Wales in recent years

25 100

20 90 15

10 80 5

0 70

−5 60 −10

1988−2006 mean −15 Percentage live capacity 50 1995−1996 2003−2004 −20 2005−2006 % devn. from 1988−2006 monthly mean 2006−2007 −25 40 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

These plots are based on the England and Wales figures listed below. Percentage live capacity of selected reservoirs at start of month

Area Reservoir Capacity (Ml) 2007 Oct Min. Year* 2006 Diff Aug Sep Oct Anom. Oct of min. Oct 07-06 North West N Command Zone • 124929 85 77 72 20 13 1995 58 14 Vyrnwy 55146 96 95 90 24 26 1995 59 31 Northumbrian Teesdale • 87936 98 87 88 26 31 1995 62 26 Kielder (199175) (94) (87) (82) -2 (59) 1989 (83) -1 Severn Trent Clywedog 44922 100 93 88 21 24 1989 51 37 Derwent Valley • 39525 100 90 86 25 24 1989 70 16 Yorkshire Washburn • 22035 95 87 81 19 24 1995 77 4 Bradford supply • 41407 97 92 87 24 15 1995 65 22 Anglian Grafham (55490) (94) (95) (93) 12 (46) 1997 (80) 13 Rutland (116580) (94) (89) (86) 8 (61) 1995 (71) 15 Thames • 202406 82 77 84 10 53 1997 75 9 Farmoor • 13822 94 100 93 4 54 2003 98 -5 Southern Bewl 28170 83 79 72 9 32 1990 61 11 Ardingly 4685 100 93 81 17 32 2003 66 15 Wessex Clatworthy 5364 100 100 88 36 25 2003 49 39 Bristol WW • (38666) (96) (95) (87) 28 (31) 1990 (69) 18 South West Colliford 28540 82 83 80 15 38 2006 38 42 Roadford 34500 99 95 91 24 26 1995 47 44 Wimbleball 21320 100 98 91 30 30 1995 60 31 Stithians 5205 90 83 73 21 22 1990 36 37 Welsh Celyn and Brenig • 131155 100 97 96 19 39 1989 76 20 Brianne 62140 100 98 98 16 48 1995 77 21 Big Five • 69762 98 90 82 20 19 1995 44 38 Elan Valley • 99106 99 93 94 21 34 1995 58 36

Scotland(E) Edinburgh/Mid Lothian • 97639 91 88 84 9 43 1998 79 5 East Lothian • 10206 100 100 100 23 52 1989 66 34 Scotland(W) Loch Katrine • 111363 70 67 61 -11 43 1995 77 -16 Daer 22412 100 96 88 17 32 1995 86 2 Loch Thom • 11840 71 72 68 -11 56 1995 94 -26

Northern Total+ • 67270 86 89 78 9 29 1995 76 2 Ireland Silent Valley • 20634 92 97 82 21 27 1995 72 10 () figures in parentheses relate to gross storage • denotes reservoir groups +excludes Lough Neagh *last occurrence

Details of the individual reservoirs in each of the groupings listed above are available on request. The percentages given in the Average and Minimum storage columns relate to the 1988-2006 period 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 are kept below capacity during the winter to provide scope for flood attenuation purposes. 10 Location map . . . Location map

gauging station Naver groundwater index well reservoir - individual reservoir - group (general location only)

Ewe

Chalk Carron Deveron Spey Jurassic limestones Ness Permo-Triassic sandstones

Dee Magnesian Limestone Nevis Minor aquifers (including the Carboniferous Limestone) have been omitted. Tay Earn Loch Katrine

Luss Forth Leven Tyne East Lothian Loch Clyde Thom Whiteadder

Tweed Edin/Mid Lothian Nith Daer Loch Bradan Kielder Cree Bush Newbridge Lower Faughan Bann Eden Killyglen South Tyne Mourne Swan Skirwith House Camowen Lagan Teesdale Northern Leven Annacloy Command Zone Wharfe

Silent Valley Wetwang Lune Bradford

Washburn Derwent Ribble Brick Dalton Holme House Yew Tree Farm Farm Torne Aylesby

Derwent Valley

Morris Dancers Lud Llanfair D.C Dover Witham Llyn Brenig Alstonfield Beck Llyn Celyn Dee Dove Trent Vyrnwy Heathlanes New Red Lion Washpit Farm Nuttalls Weeford Rutland Water Stringside Clywedog Flats Farm Soar

Great Ouse Little Ouse Severn Grafham Water Elan Valley Teme Dial Llyn Avon Redlands Hall Farm Brianne Yscir Wye Teifi Mimram Therfield Coln Colne Farmoor Rectory Stonor Cynon Ampney Lee Tawe Big Crucis Park Five Lambourn Rockley London Blackwater Thames Bristol Well TilsheadAvon Kennet Water Mole House Little Bucket Farm West Test Inn edway Woodyates Compton M Great Stour Wimbleball Clatworthy Lymington Ardingly Taw Brue Manor House Ouse Exe Stour Chilgrove Bewl Water Tone Itchen Piddle House Houndean Bottom Roadford Otter Lime Kiln Way Wallington Bussels Westdean No.3 No.7A Ashton Farm Colliford Dart

Kenwyn Warleggan Stithians

11 National Hydrological Monitoring Programme

The National Hydrological Monitoring Programme The monthly rainfall figures are provided by the Met Office (NHMP) was instigated in 1988 and is undertaken jointly (National Climate Information Centre) and are Crown by the Centre for Ecology and Hydrology Wallingford Copyright and may not be passed on to, or published by, (formerly the Institute of Hydrology - IH) and the British any unauthorised person or organisation. Geological Survey (BGS). Financial support for the production of the monthly Hydrological Summaries is *MORECS is the generic name for the Met Office services provided by the Department for Environment, Food and involving the routine calculation of evaporation and soil Rural Affairs (Defra), the Environment Agency (EA), the moisture throughout Great Britain. Scottish Environment Protection Agency (SEPA), the The Met Office Rivers Agency (RA) in Northern Ireland, and the Office FitzRoy Road of Water Services (OFWAT). Exeter Devon Data Sources EX1 3PB River flow and groundwater level data are provided by the Environment Agency, the Environment Agency Wales, Tel.: 0870 900 0100 Fax: 0870 900 5050 the Scottish Environment Protection Agency and, for E-mail: [email protected] Northern Ireland, the Rivers Agency and the Department of the Environment (NI). In all cases the data are subject to revision following validation (flood and drought data The National Hydrological Monitoring Programme in particular may be subject to significant revision). depends on the active cooperation of many data suppliers. Reservoir level information is provided by the Water This cooperation is gratefully acknowledged. Service Companies, the EA, Scottish Water and the Northern Ireland Water Service. Subscription Subscription to the Hydrological Summaries costs £48 per The National River Flow Archive (maintained by CEH year. Orders should be addressed to: Wallingford) and the National Groundwater Level Archive (maintained by BGS) provide the historical perspective Hydrological Summaries within which to examine contemporary hydrological National Water Archive conditions. CEH Wallingford Maclean Building Rainfall Crowmarsh Gifford Most rainfall data are provided by the Met Office (see Wallingford opposite). To allow better spatial differentiation the Oxfordshire rainfall data for Britain are presented for the regional OX10 8BB divisions of the precursor organisations of the EA and SEPA. Following the discontinuation of the Met Office’s Tel.: 01491 838800 CARP system in July 1998, the areal rainfall figures have Fax: 01491 692424 been derived using several procedures, including initial E-mail: [email protected] estimates based on MORECS*. Recent figures have been produced by the Met Office, National Climate Information Centre (NCIC), using a technique similar to CARP. A Selected text and maps are available on the WWW at significant number of additional monthly raingauge totals http://www.nerc-wallingford.ac.uk/ih/nrfa/index.htm are provided by the EA and SEPA to help derive the Navigate via Water Watch contemporary regional rainfalls. Revised monthly national and regional rainfall totals for the post-1960 period Some of the features displayed in the maps contained in (together with revised 1961-90 averages) were made this report are based on the Ordnance Survey BaseData available by the Met Office in 2004; these have been GB and 1:50,000 digital data (Licence no. GD03012G/ adopted by the NHMP. As with all regional figures based 01/97) and are included with the permission of Her on limited raingauge networks the monthly tables and Majesty’s Stationery Office. © Crown Copyright. accumulations (and the return periods associated with them) should be regarded as a guide only. Rainfall data supplied by the Met Office are also Crown Copyright. Unauthorised reproduction infringes Crown Copyright and may lead to prosecution.

© This document is copyright and may not be reproduced without the prior permission of the Natural Environment Research Council. 10/07 12