Hydrological Summary for the

General May began dry and warm in most areas but a very moist westerly airflow predominated thereafter. Correspondingly, and Wales registered its wettest May for 27 years with most regional totals exceeding 150% of the monthly average. Despite increasing evaporation losses, reservoir stocks generally increased, reaching around 4% above average for E&W as a whole by early June, with typical early summer stocks characterising most of the drought- affected region. The wet May was agriculturally welcome but notable storm events triggered a number of flood alerts and reversed, albeit briefly, the seasonal decline in river flows. May runoff totals were spatially very variable but mostly within the normal range. Exceptions included some groundwater-fed streams where the May runoff was close to period of record minima. Modest, but very useful, late spring aquifer recharge has reduced the spatial extent of the groundwater drought – now largely confined to a broad zone from the Midlands to the South East with especially depressed groundwater levels in the Chilterns and parts of the North Downs. A particularly arid episode, extending well into June, with an associated increase in water demand, has underlined the fragility of water resources in such areas. In a groundwater context particularly, the possibility of a third successive dry winter – a rare occurrence in the last 100 years but more frequent in the 19th century – has become an influential factor in the implementation of drought mitigation measures. Rainfall Apart from the beginning and end of the month, cyclonic high monthly runoff totals were common – in Wales and conditions dominated synoptic patterns in May. Damaging northern England especially. In Northern Ireland the River thunderstorms in north-western Britain (e.g. Glasgow) on Camowen registered its highest May runoff in a 35-yr the 4th and sustained frontal rainfall across southern Britain record. Flows in rivers draining permeable catchments on the 6/7th heralded a notably wet three-week period with (in the Chalk particularly) showed a much more muted measurable rainfall recorded on all but a few days. The response to the May rainfall but the modest recoveries resulting media refrain of ‘the wettest drought on record’ were often sufficient to register the highest daily flows of failed to acknowledge that such circumstances are not rare 2006 thus far (e.g. on the Lambourn and Itchen). in the English Lowlands where groundwater resources Nonetheless, May runoff totals were notably low in a status is a crucial factor; there are many more spring/ number of spring-fed rivers and accumulated runoff totals summer episodes more deserving of such an accolade. Dry (for the duration of the drought) remain very low across conditions at month end extended beyond a fortnight - much of central and southern England. with some localities in central southern England reporting <1mm of rain. May rainfall totals were below average in Groundwater some catchments in eastern Scotland but most of the Across most major aquifer outcrop areas, May rainfall drought-affected region registered > 150%; some areas totals exceeded the average by 50-80% but spatial were especially wet (e.g. the , south variations in soil moisture conditions, land use and and coastal areas of eastern England; the Isle of Man also). evaporative demands produced a very spatially The wet May contributed to the third wettest spring for heterogeneous response in terms of recharge. Not all of E&W in the last 20 years but for parts of the drought- the May infiltration will yet have reached the more affected region (including the Thames basin), May was depressed water-tables but it triggered appreciable May 2006 the only the second month with above average rainfall groundwater level increases in some responsive limestone since October 2004. Correspondingly long term rainfall aquifers – particularly in the Oolitic Limestone of the deficiencies remain high in much of eastern and southern Cotswolds (see Ampney Crucis ), and useful seasonally England. Rainfall over the Nov. 2004 - May 2006 period late upturns some minor aquifers (e.g. the Upper is >25% below average for some (restricted) areas of Greensand on the Isle of Wight and the Essex Gravels). southern England and for the Thames basin the 19-month nd The wet spring has been beneficial across much of the total is the 2 lowest (after 1995-97) since 1944. Chalk also – particularly the more southerly and westerly outcrops – where levels are currently well above early River Flow summer drought minima (e.g. those of 1997, 1992 and In most responsive catchments river flows exhibited an 1976). Accordingly, there has been an appreciable exceptional range in May. Flows in the Ribble reduction in the area afflicted by severe groundwater (Lancashire) closely approached early May minima but drought conditions – this now embraces some Permo- recovered dramatically with high spate conditions in the Triassic outcrops in the Midlands (see Morris Dancers) third week. In York, the Ouse exceeded bankfull on the and, especially, the Chalk of the Chilterns and parts of 23rd and Flood Watches were common in the latter half of the North Downs (extending into Kent). At Stonor (in the month – by which time flows in many field drains had the Chilterns), the May groundwater level was the 2nd recommenced (e.g. in Essex). Flow recoveries were lowest (after 1997) in a 46-year record whilst Well House particularly valuable in the English Lowlands, allowing Inn (North Downs) reported its 2nd lowest (after 1944) in continuing abstractions to supplement pumped-storage a 65-yr record. In such areas summer recessions are reservoir stocks. The Yorkshire Derwent, Exe, Dart and expected to approach natural base levels with a continuing Nevis were among a significant proportion of index rivers failure of lower level springs and an associated further registering new maximum daily flows for May and notably contraction in the stream network. Rainfall . . . Rainfall . . .

Rainfall accumulations and return period estimates Area Rainfall May 2006 Mar 06- May 06 Nov 05- May 06 Jun 05- May 06 Nov 04- May 06 RP RP RP RP England mm 111 245 491 864 1278 & Wales % 176 125 5-10 91 2-5 95 2-5 88 5-10 North West mm 119 317 655 1127 1787 % 157 130 5-10 95 2-5 93 2-5 94 2-5 Northumbrian mm 90 235 478 862 1347 % 144 123 5-10 95 2-5 99 2-5 98 2-5 Severn Trent mm 102 213 400 745 1062 % 171 120 2-5 88 2-5 97 2-5 87 5-10 Yorkshire mm 113 264 478 825 1213 % 187 140 10-20 97 2-5 99 2-5 92 2-5 Anglian mm 94 173 299 587 835 % 193 122 2-5 87 2-5 97 2-5 88 5-10 Thames mm 98 193 361 627 892 % 174 118 2-5 87 2-5 89 2-5 80 15-25 Southern mm 92 190 402 701 998 % 169 112 2-5 85 2-5 89 2-5 79 20-30 Wessex mm 109 202 454 789 1156 % 177 109 2-5 87 2-5 92 2-5 84 5-15 South West mm 109 253 629 1082 1623 % 148 104 2-5 83 5-10 91 2-5 83 10-20 Welsh mm 167 387 802 1337 1985 % 198 140 10-20 98 2-5 99 2-5 92 2-5 Scotland mm 117 358 815 1425 2439 % 136 121 5-10 94 2-5 97 2-5 104 2-5 Highland mm 137 434 1028 1764 3124 % 146 125 5-10 98 2-5 101 2-5 112 5-15 North East mm 80 230 565 964 1584 % 109 103 2-5 95 2-5 94 2-5 97 2-5 Tay m m 113 319 699 1196 2021 % 131 119 2-5 90 2-5 93 2-5 98 2-5 Forth mm 101 274 571 1049 1807 % 132 116 2-5 86 5-10 92 2-5 100 <2 Tweed mm 82 234 505 944 1506 % 112 108 2-5 87 2-5 94 2-5 95 2-5 Solway mm 116 381 778 1334 2202 % 132 133 5-15 93 2-5 93 2-5 97 2-5 Clyde mm 145 414 916 1638 2814 % 152 123 5-10 90 2-5 94 2-5 102 2-5 Northern mm 117 324 608 1019 1653 Ireland % 160 140 10-20 94 2-5 93 2-5 95 2-5 % = percentage of 1961-90 average RP = Return period The monthly rainfall figures* provided by the Met Office (National Climate Information Centre) are Crown Copyright and may not be passed on to, or published by, any unauthorised person or organisation. All monthly totals since December 2005 are provisional (see page 12). 1961-2003 regional monthly 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 (return periods 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 based on the tables for north-west England. The tables reflect rainfall over the period 1911-70 and assume a stable climate. Artifacts, in the Scottish rainfall series in particular, can exaggerate the relative wetness of the recent past. *See page 12.

2 Rainfall . . . Rainfall . . .

Key

00% Percentage of 1961-90 average Normal range

Ver y wet Below average

Substantially above average Substantially below average

Above average Exceptionally low rainfall

125% 112%

103% 97%

119% 98%

116% 100%

123% 102% 108% 95%

133% 97% 123% 98% 140% 95%

130% 140% 94% 92%

120% 87% 122% 88%

140% 92%

118% 80%

109% 112% 84% 79%

104% 83%

March 2006 - May 2006 November 2004 - May 2006

Rainfall accumulation maps

Provisional data suggest that spring (March-May) was the equal 6th wettest for the UK in a series from 1914 – with above average rainfall in all regions. By contrast, only northern Scotland registered above average rainfall in the 19-month timeframe and notable long term deficiencies extend across most of southern England.

3 River flow . . . River flow . . .

!(87 Naver

!(110 Ewe Spey Ness !(85 !(129 !(116 Carron

Dee !(76 May 2006 !(166 Nevis Tay !(108 Earn !(119 !(142 Luss Whiteadder 99 Clyde!( !(71 100 Naver !( !(83 Tweed 132 South !( 97 Nith Tyne Bush !( 100 Cree 155 !( 128 !( 111 Ewe !( !( J!(235 Eden Camowen 218 117 Spey Annacloy 199 !(Leven 101 105 Ness !( !( !( !( Lune Carron Derwent 138 !( !(169 199 86 !( Dee !( !(190 Wharfe !(102 Nevis Ribble Tay Lud!(68 !(102 Trent Dee Dove !(88 Earn 106 !(131 Witham !( !(230 !(170 Little 85 Luss Ouse !( Soar!(154 Severn !(76 Whiteadder !(176 82 Clyde!( 87 Teme 171 Great !( !( 175 !(113 Colne !(185 Yscir !(Avon Ouse 84 !(180 Wye 118 !( Teifi Coln Mimram 43 !( 182 !( 70 Lee Twee d Cynon !( !(84 !( !(223 South 95 Lambourn 78 103 !( 86 Nith !(49!( !( !( Tyne 117 Great 122 Bush Kennet Thames !( !( Stour 89 93 Avon!(72 !( Cree !( Medway 93 110 !( 190 !( Ton e 82 Itchen Ouse 147 Taw !( !( !( 102 Eden 197 Exe !( !( Stour !(118 Camowen !(107 Leven !(85 Warle ggan Annacloy !(85 Kenwyn Lune !(96 Derwent 86 !( !(97 !(82 !(84 Wharfe Key Ribble % of long-term average Lud!(71 25 J (record figure when circled) Trent Dee Dove !(73 !(74 Witham Exceptionally high flow !(93 !(86 !( Little Ouse Soar!(56 !( Notably high flow Severn 75 !(72 !( Tem e !( Above normal !(74 57 Great 62 !( !(90 Yscir !(Avon Ouse Colne !(87 Wye 65 Normal range Teifi Coln 54 !( !( 80 Mimram !( !( 68 54 Lee Cynon !( !( !(79 !( Below normal Lambourn !(60 !(60 37% 67 Great Kennet Tha mes !( !( !( Notably low flow Avon!(58 J Stour 72 Medway !(76 !( Ton e !(74 Itchen Ouse !(44% Exceptionally low flow Taw J !( 76 !(Exe 60% Stour !( J Based on ranking of the monthly flow* !(81 Warleggan Kenwyn J!(69% November 2004 - May 2006

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 2005/2006 England and Wales 2005/2006 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 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 600021 Daily mean flows Station No: 600041 Daily mean flows + extreme daily flows (1961 to 2006) + extreme daily flows (1961 to 2006)

Scotland 2005/2006 Northern Ireland 2005/2006 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 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 600061 Daily mean flows Station No: 600081 Daily mean flows + extreme daily flows (1961 to 2006) + extreme daily flows (1980 to 2006)

Ewe at Poolewe 2005/2006 Tay at Ballathie 2005/2006 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 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 094001 Daily mean flows Station No: 015006 Daily mean flows + extreme daily flows (1970 to 2006) + extreme daily flows (1952 to 2006)

Clyde at Daldowie 2005/2006 Derwent at Buttercrambe 2005/2006 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 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 084013 Daily mean flows Station No: 027041 Daily mean flows + extreme daily flows (1963 to 2006) + extreme daily flows (1973 to 2006)

Camowen at Camowen Terrace 2005/2006 Bush at Seneirl Bridge 2005/2006 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 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 201005 Daily mean flows Station No: 204001 Daily mean flows + extreme daily flows (1972 to 2006) + extreme daily flows (1972 to 2006)

River flow hydrographs The river flow hydrographs show the daily mean flows together with the maximum and minimum daily flows prior to June 2005 (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 2005/2006 Trent at Colwick 2005/2006 1000 1000

500 500

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

Gauged Discharge 20 Gauged Discharge

10 20

5 10 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 076007 Daily mean flows Station No: 028009 Daily mean flows + extreme daily flows (1967 to 2006) + extreme daily flows (1958 to 2006)

Severn at Bewdley 2005/2006 Lud at Louth 2005/2006 1000 5

500 2

200 1 100 -1 -1 s s 3 0.5 3 50 m m

Gauged Discharge Gauged Discharge 0.2 20

10 0.1

5 0.05 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 054001 Daily mean flows Station No: 029003 Daily mean flows + extreme daily flows (1921 to 2006) + extreme daily flows (1968 to 2006)

Teifi at Glan Teifi 2005/2006 Colne at Lexden 2005/2006 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 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 062001 Daily mean flows Station No: 037005 Daily mean flows + extreme daily flows (1959 to 2006) + extreme daily flows (1959 to 2006)

Cynon at Abercynon 2005/2006 Thames at Kingston 2005/2006 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 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 057004 Daily mean flows Station No: 039001 Daily mean flows + extreme daily flows (1957 to 2006) + extreme daily flows (1883 to 2006)

Stour at Throop 2005/2006 Itchen at Highbridge+Allbrook 2005/2006 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 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Station No: 043007 Daily mean flows Station No: 042010 Daily mean flows + extreme daily flows (1973 to 2006) + extreme daily flows (1958 to 2006)

Notable runoff accumulations (a) May 2006, (b) November 2004 - May 2006 River %lta Rank River %lta Rank River %lta Rank a) Mimram 43 4/54 b) Soar 56 2/34 Wallington 46 1/47 Lamborn 49 5/44 Blackwater 71 3/53 Test 63 1/46 Mole 236 31/33 Kennet 60 2/44 Itchen 74 2/47 Cynon 223 46/48 Lambourn 56 2/43 Stour (Throop) 60 1/32 Tawe 216 46/49 Mole 64 1/29 Piddle 62 1/40 Dee (New Inn) 230 35/37 Medway 37 1/41 Kenwyn 69 1/37 Nevis 166 22/24 Ouse (Gold Bridge) 44 1/38 Faughan 75 2/29 Camowen 235 35/35 lta = long term average 6 Rank 1 = lowest on record 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 2003 2004 2005 2006 2003 2004 2005 2006 Well No: SE94/5 Aquifer: Chalk Well No: TF81/2A Aquifer: Chalk + extremes & mean monthly levels (1889-2002) + extremes & mean monthly levels (1950-2002)

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 2003 2004 2005 2006 2003 2004 2005 2006 Well No: SU78/45A Aquifer: Chalk Well No: TM15/112 Aquifer: Chalk + extremes & mean monthly levels (1961-2002) + extremes & mean monthly levels (1968-2002)

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

2003 2004 2005 2006 2003 2004 2005 2006 Well No: SU17/57 Aquifer: Chalk Well No: TQ25/13 Aquifer: Chalk + extremes & mean monthly levels (1933-2002) + extremes & mean monthly levels (1942-2002)

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

2003 2004 2005 2006 2003 2004 2005 2006 Well No: SU01/5B Aquifer: Chalk Well No: SU81/1 Aquifer: Chalk + extremes & mean monthly levels (1942-2002) + extremes & mean monthly levels (1836-2002)

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

2003 2004 2005 2006 2003 2004 2005 2006 Well No: ID30/1 Aquifer: Chalk Well No: TF03/37 Aquifer: Lincolnshire Limestone + extremes & mean monthly levels (1985-2002) + extremes & mean monthly levels (1964-2002)

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

2003 2004 2005 2006 2003 2004 2005 2006 Well No: SP00/62 Aquifer: Middle Jurassic Well No: NX97/2 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1958-2002) + extremes & mean monthly levels (1993-2002)

Skirwith Brick House Farm

16.0 16.0 131.0 131.0 14.0 14.0

130.0 130.0 12.0 12.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 53.34 Measuring level : 133.25 10.0 10.0 2003 2004 2005 2006 2003 2004 2005 2006 Well No: NY63/2 Aquifer: Permo-Triassic sandstone Well No: SE44/80 Aquifer: Magnesian Limestone + extremes & mean monthly levels (1978-2002) + extremes & mean monthly levels (1979-2002)

Llanfair DC Morris Dancers

81.0 81.0 33.0 33.0 80.0 80.0

32.0 32.0 79.0 79.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 83.08 Measuring level : 54.83

2003 2004 2005 2006 2003 2004 2005 2006 Well No: SJ15/13 Aquifer: Permo-Triassic sandstone Well No: SK67/17 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1972-2002) + extremes & mean monthly levels (1969-2002)

Heathlanes Nuttalls Farm

64.0 64.0 132.0 132.0

130.0 130.0 62.0 62.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 68.61 128.0 128.0 Measuring level : 141.78 2003 2004 2005 2006 2003 2004 2005 2006 Well No: SJ62/112 Aquifer: Permo-Triassic sandstone Well No: SK00/41 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1971-2002) + extremes & mean monthly levels (1974-2002)

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 2003 2004 2005 2006 2003 2004 2005 2006 Well No: SX99/37B Aquifer: Permo-Triassic sandstone Well No: SK15/16 Aquifer: Carboniferous Limestone + extremes & mean monthly levels (1971-2002) + extremes & mean monthly levels (1974-2002) Groundwater levels May / June 2006 Borehole Level Date May. av. Borehole Level Date May. av. Borehole Level Date May. av. Dalton Holme 17.97 31/05 18.95 Chilgrove House 48.16 31/05 48.96 Llanfair DC 79.96 01/05 79.97 Washpit Farm 43.19 02/06 45.50 Killyglen 114.89 31/05 114.51 Morris Dancers 31.60 29/05 32.35 Stonor Park 64.61 31/05 78.23 New Red Lion 13.22 30/05 15.89 Heathlanes 60.88 24/05 62.09 Dial Farm 25.18 12/05 25.71 Ampney Crucis 102.24 31/05 101.28 Nuttalls Farm 128.60 04/05 129.61 Rockley 133.67 31/05 136.19 Newbridge 10.05 31/05 10.32 Bussels No.7a 23.84 18/05 24.00 Well House Inn 87.23 19/05 97.15 Skirwith 130.45 22/05 130.58 Alstonfield 186.82 15/05 186.77 West Woodyates 84.06 31/05 84.62 Brick House Farm 12.31 24/05 13.37 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 !(1/1 4 Magnesian Limestone Killyglen 14/21 !( Swan House Permo-Triassic sandstones Skirwith !(7/ 24 !(23/ 33 Jurassic limestones

Wetwang Chalk

24/ 35 Brick !( Dalton House 9/2 5 30/118 !( Home!( Fa rm Yew !( Tr ee 6/ 25 Fa rm Aylesby !(

Alstonfield 2/ 36 Morris !(Dancers !(14/35 !(17/32 Llanfair !(10/ 43 Washpit D.C. 4/3 2 9/5 5 !( Weeford !( Fa rm !(5/ 40 Fl ats New Red Lion Heathl anes !(7/ 30 Dial Nuttalls Redlands Fa rm Fa rm Hall !(5/3 5 3/ 42 Th erf ie ld !( Ampney !(18 /1 20 Crucis Rectory !(43/ 48 Stonor Park !(2/ 46 Rockley !(12/73 Well 2/6 3 House Littl e !(6/ 34 Ti lshead !( Inn 8/3 4 Lime West !( Bucket Compton Chilgrove Kiln Woodyates Houndean Fa rm 23/62 House House Way Manor !( !(43 /1 12!(74/ 17 1 !(9/2 9 5/37 Bussels !(10/34 !( !(11/65 Westdean No 3 No 7A !(7/3 3 Ashton Farm

Groundwater levels - May 2006 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. ii. Yew Tree Farm levels are now received quarterly. 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

−15 Percentage live capacity 1988−2005 mean 50 1989/90 −20 1995/96 % devn. from 1988−2005 monthly mean 1996/97 2005/06 −25 40 1997 1998 1999 2000 2001 2002 2003 2004 2005 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May

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) 2006 Avg. Min. Year* Feb Mar Apr May Jun Jun Jun of min. North West N Command Zone • 124929 89 90 100 91 85 83 72 1991 Vyrnwy 55146 91 90 100 98 98 89 72 1990 Northumbrian Teesdale • 87936 94 100 100 94 95 86 64 1991 Kielder (199175) (93) (92) (98) (89) (93) (92) (85) 1989 Severn Trent Clywedog 44922 87 88 99 100 100 96 83 1989 Derwent Valley • 39525 93 98 100 99 100 88 56 1996 Yorkshire Washburn • 22035 85 89 99 94 98 87 72 1990 Bradford supply • 41407 82 83 97 95 99 86 70 1996 Anglian Grafham (55490) (85) (89) (96) (99) (100) (93) (72) 1997 Rutland (116580) (80) (83) (88) (91) (93) (91) (75) 1997 Thames London • 202406 92 98 99 91 93 93 83 1990 Farmoor • 13822 93 99 97 99 100 98 90 2002 Southern Bewl 28170 37 50 65 85 91 87 57 1990 Ardingly 4685 65 77 88 100 100 99 96 1990 Wessex Clatworthy 5364 100 100 100 98 86 87 67 1990 Bristol WW • (38666) (76) (81) (87) (92) (96) (88) (70) 1990 South West Colliford 28540 60 62 68 70 70 85 52 1997 Roadford 34500 69 71 76 75 77 83 48 1996 Wimbleball 21320 84 95 100 99 100 91 76 1992 Stithians 5205 83 88 96 94 90 86 66 1990 Welsh Celyn and Brenig • 131155 96 98 100 100 100 97 82 1996 Brianne 62140 95 95 100 100 100 96 85 1995 Big Five • 69762 97 97 99 97 96 90 70 1990 Elan Valley • 99106 98 98 100 99 100 95 85 1990

Scotland(E) Edinburgh/Mid Lothian • 97639 95 94 96 92 92 89 52 1998 East Lothian • 10206 100 99 100 100 99 96 84 1990 Scotland(W) Loch Katrine • 111363 94 95 99 94 98 88 66 2001 Daer 22412 100 99 100 97 94 91 70 1994 Loch Thom • 11840 100 100 100 100 100 90 74 2001

Northern Total+ • 67270 90 88 93 89 89 86 74 2004 Ireland Silent Valley • 20634 94 90 98 93 94 80 56 2000 () figures in parentheses relate to gross storage • denotes reservoir groups +excludes Lough Neagh *last occurrence - see footnote

Details of the individual reservoirs in each of the groupings listed above are available on request. The featured reservoirs may not be representative of the 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 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 *MORECS is the generic name for the Met Office services (NHMP) was instigated in 1988 and is undertaken jointly involving the routine calculation of evaporation and soil by the Centre for Ecology and Hydrology Wallingford moisture throughout Great Britain. (formerly the Institute of Hydrology - IH) and the British Geological Survey (BGS). Financial support for the The Met Office production of the monthly Hydrological Summaries is FitzRoy Road provided by the Department for Environment, Food and Exeter Rural Affairs (Defra), the Environment Agency (EA), the Devon Scottish Environment Protection Agency (SEPA), the EX1 3PB Rivers Agency (RA) in Northern Ireland, and the Office of Water Services (OFWAT). Tel.: 0870 900 0100 Fax: 0870 900 5050 Data Sources E-mail: [email protected] River flow and groundwater level data are provided by the Environment Agency, the Environment Agency Wales, The National Hydrological Monitoring Programme the Scottish Environment Protection Agency and, for depends on the active cooperation of many data suppliers. Northern Ireland, the Rivers Agency and the Department This cooperation is gratefully acknowledged. of the Environment (NI). In all cases the data are subject to revision following validation (flood and drought data Subscription in particular may be subject to significant revision). Subscription to the Hydrological Summaries costs £48 per year. Orders should be addressed to: Reservoir level information is provided by the Water Service Companies, the EA, Scottish Water and the Hydrological Summaries Northern Ireland Water Service. National Water Archive CEH Wallingford The National River Flow Archive (maintained by CEH Maclean Building Wallingford) and the National Groundwater Level Archive Crowmarsh Gifford (maintained by BGS) provide the historical perspective Wallingford within which to examine contemporary hydrological Oxfordshire conditions. OX10 8BB

Rainfall Tel.: 01491 838800 Most rainfall data are provided by the Met Office (see Fax: 01491 692424 opposite). To allow better spatial differentiation the E-mail: [email protected] rainfall data for Britain are presented for the regional divisions of the precursor organisations of the EA and Selected text and maps are available on the WWW at SEPA. Following the discontinuation of the Met Office’s http://www.nerc-wallingford.ac.uk/ih/nrfa/index.htm CARP system in July 1998, the areal rainfall figures have Navigate via Water Watch been derived using several procedures, including initial estimates based on MORECS*. Recent figures have been Some of the features displayed in the maps contained in produced by the Met Office, National Climate Information this report are based on the Ordnance Survey BaseData Centre (NCIC), using a technique similar to CARP. A GB and 1:50,000 digital data (Licence no. GD03012G/ significant number of additional monthly raingauge totals 01/97) and are included with the permission of Her are provided by the EA and SEPA to help derive the Majesty’s Stationery Office. © Crown Copyright. contemporary regional rainfalls. Revised monthly national Rainfall data supplied by the Met Office are also Crown and regional rainfall totals for the post-1960 period Copyright. Unauthorised reproduction infringes Crown (together with revised 1961-90 averages) were made Copyright and may lead to prosecution. available by the Met Office in 2004; these have been adopted by the NHMP. As with all regional figures based © This document is copyright and may not be reproduced on limited raingauge networks the monthly tables and without the prior permission of the Natural Environment accumulations (and the return periods associated with Research Council. them) should be regarded as a guide only.

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