Hydrological Summary for the United Kingdom General October was an exceptionally mild month but the spatial distribution of the rainfall was again remarkable – triggering flooding in many western and northern regions but increasing long term rainfall deficiencies across much of the English Lowlands where drought conditions are severe in some areas. Whilst Northern Ireland registered its 2nd wettest October on record, a few places in the South East recorded less than a quarter of the average monthly rainfall. High runoff rates in the gathering grounds of most upland reservoirs helped maintain healthy stocks and, despite drawdowns to provide additional flood storage, estimated overall stocks for Scotland, Wales and Northern Ireland remain well above aver- age. However, exceptionally dry autumn soils in central, southern and eastern England – which caused problems for lifting and sowing crops – continue to delay the seasonal recovery in runoff rates. Correspondingly inflows to many gravity-fed reservoirs were meagre and early-November stocks were more than 20% below average in some central and southern impoundments (e.g. Ardingly, Clatworthy and Wimbleball,) Several index rivers recorded new minimum October mean flows and, more notably, March-October runoff totals are depressed in a broad zone extending through the Midlands and the South West. After very sustained recessions, groundwater levels are well below average in almost all but the most northerly index wells. Resort to tankered supplies was required after the failure of springs and private wells in Shropshire, and in Wiltshire, the Tilshead borehole went dry at the end of October – for the first time since the intense drought of 1976. Above average late autumn and winter rainfall is needed in much of central, southern and eastern England to secure a healthy water resources outlook by the spring of 2012. Rainfall The persistence of a high pressure extending west from reported its 3rd highest October mean flow in a series from the continent resulted in most rain-bearing Atlantic fron- 1963. In stark contrast, flow recessions continued across tal systems following tracks to the west and north of the the English Lowlands where October runoff for the Little English Lowlands throughout much of October. Corre- Ouse, Soar, Teme, Winterbourne (Berks) and Hampshire spondingly, storms were frequent in Northern Ireland and Avon all fell below previous minima. In runoff terms the western Scotland where daily rainfall totals of >50mm intensity of the drought in southern Britain is underlined were relatively common (e.g. Cluanie Inn 57mm on the by the accumulated deficiencies over the March-October 22nd and Tyndrum 58.4mm on 29th) and in the South West period. A significant proportion of index catchments, Cardinham (on Bodmin Moor) recorded 67.2mm on 24th. including the Wye, Severn, Otter, Tone and Medway By contrast, rainfall was limited across much of the Mid- (each with long records) have registered new accumulated lands, East Anglia and the South East, particularly early runoff minima. After protracted recessions, flows in in the month; at Wallingford 2mm was recorded over the many baseflow-dominated streams are very depressed as first two weeks. Much of the South East reported less than inflows from higher level springs and seepages cease; in half of the average monthly rainfall, adding to an extended some rivers (e.g. the Itchen) flow augmentation schemes sequence of moderate rainfall totals. Rainfall deficiencies are operating. for March-October are notably high across large parts of southern Britain, particularly for the Midland region where Groundwater the 8-month rainfall total closely matched the lowest on Whilst soils in almost all northern and western areas record (1995) in a 101-year series. In this timeframe, remain close to saturation, the warm and sunny October pockets of particularly severe drought can be found in (and the associated evaporation demands) resulted in end- Shropshire, the Cotswolds and across the East Midlands of-month soil moisture deficits exceeding 100mm (for a (see Page 3) where some localities received less than half grass cover) over large parts of the central, southern and the average rainfall. The unusual spatial partitioning of the eastern England. In these regions soils were, generally, 2011 rainfall is underlined by the contrast with Scotland the driest for late October since 1978. Correspondingly, where the previous maximum March-October rainfall recharge in the outcrop areas of most major aquifers was was exceeded by a very wide margin. To the south, the meagre. Some local recoveries in groundwater levels were hydrological impact of the current drought reflects rainfall recorded: In Northern Ireland and southern Scotland the 2011 October deficiencies that can be traced back to December 2009. exceptional rainfall triggered further rises at both Killyglen and Newbridge. Generally however, recessions continue River Flows and groundwater levels in almost all index boreholes are River flow patterns in October defy easy categorisation: below, to well below, the late October average. Particular- notable flooding occurred in Northern Ireland, sustained ly depressed levels characterise the western Chalk where, spate conditions were common in northern Britain and in the more responsive wells and boreholes, natural base urban flash flood events were widespread late in the levels are being approached over wide areas. At Tilshead month. More notably, exceptionally low autumn flows the well is dry and levels at Rockley (Wilts) are very close characterised many central and southern rivers and the to the lowest on record. Spring failures as a result of fall- continuing contraction in the stream network has resulted ing groundwater levels have been widely reported (e.g. in a significant, albeit temporary, loss of aquatic habitat. In in Shropshire, Lincolnshire and Somerset). Considering Northern Ireland a sequence of notable spates culminated, the major aquifers together groundwater resources across on the 24th, in severe flooding (e.g. in Antrim and Tyrone) southern Britain are at their lowest since the end of the and widespread road closures. This event contributed to 1995-97 drought. Above average late autumn and winter new maxima October runoff totals for the majority of index rainfall will be needed to wet-up lowland soils and thence gauging stations across the province. High runoff also generate a recovery in groundwater levels to within the characterised much of western Scotland where the Cree normal spring range. Rainfall . . . Rainfall . . . Rainfall accumulations and return period estimates Percentages are from the 1971-2000 average. Oct Area Rainfall 2011 Sep11 - Oct11 Mar11 - Oct11 Nov10 - Oct11 Dec09 - Oct11 RP RP RP RP United mm 123 229 685 1073 1953 Kingdom % 109 110 2-5 106 2-5 99 2-5 95 2-5 England mm 63 116 405 688 1382 % 78 76 2-5 80 12-16 84 10-15 89 10-15 Scotland mm 205 394 1138 1671 2800 % 134 138 10-20 136 >100 116 10-20 103 2-5 Wales mm 122 243 673 1145 2234 % 83 92 2-5 85 5-10 83 10-15 86 15-20 Northern mm 208 328 764 1183 2092 Ireland % 181 157 70-100 113 2-5 107 2-5 99 2-5 England & mm 72 134 442 751 1499 Wales % 79 79 2-5 81 12-16 84 10-15 88 12-16

North West mm 135 272 784 1240 2162 % 107 119 2-5 110 2-5 105 2-5 97 2-5 Northumbria mm 80 147 567 955 1711 % 106 101 2-5 109 2-5 115 2-5 108 2-5 Midlands mm 49 84 303 516 1129 % 69 61 5-10 63 >100 68 >100 78 >100 Yorkshire mm 83 127 414 730 1402 % 109 87 2-5 82 8-12 90 5-10 91 5-10 Anglian mm 28 53 252 431 1012 % 49 48 12-16 63 35-50 71 35-50 88 5-10 Thames mm 31 68 311 526 1140 % 43 51 8-12 70 10-20 75 15-25 85 10-15 Southern mm 38 78 330 632 1357 % 43 49 5-10 70 15-25 81 8-12 92 2-5 Wessex mm 58 114 414 698 1366 % 67 70 2-5 80 8-12 81 10-15 83 20-35 South West mm 121 205 545 967 1903 % 96 91 2-5 80 8-12 80 10-20 83 20-30 Welsh mm 118 232 646 1093 2152 % 83 91 2-5 84 8-12 83 10-15 86 15-20 Highland mm 237 473 1326 1874 3115 % 131 140 10-20 137 80-120 109 5-10 97 2-5 North East mm 90 184 754 1137 2157 % 89 97 2-5 127 8-12 120 5-10 120 10-15 Tay mm 155 314 1062 1596 2635 % 116 127 5-10 145 >100 126 20-30 110 2-5 Forth mm 145 276 936 1438 2380 % 123 123 5-10 138 40-60 127 30-40 111 5-10 Tweed mm 121 225 798 1254 2121 % 127 128 2-5 136 10-20 131 20-35 117 8-12 Solway mm 236 414 1125 1726 2856 % 152 148 15-25 136 35-50 123 20-30 107 5-10 Clyde mm 307 563 1406 2057 3318 % 162 159 50-80 140 >100 119 15-20 101 2-5 % = percentage of 1971-2000 average RP = Return period Important note: Figures in the above table may be quoted provided their source is acknowledged (see page 12). Where appropriate, specific mention must be made of the uncertainties associated with the return period estimates. The RP estimates are based on data provided by the Met Office and reflect climatic variability since 1910; they also assume a stable climate. The quoted RPs relate to the specific timespans only; for the same timespans, but beginning in any month the RPs would be substantially shorter. The timespans featured do not purport to represent the critical periods for any particular water resource management zone. For hydrological or water resources assessments of drought severity, river flows and/or groundwater levels normally provide a better guide than return periods based on regional rainfall totals. All monthly rainfall totals since June 2011 are provisional.

2 Rainfall . . . Rainfall . . . Rainfall . . . Rainfall . . .

September - October 2011 November 2010 - October 2011 Key Key 25% Percentage of 1971-2000 average 25% Percentage of 1971-2000 average Exceptionally low rainfall Exceptionally low rainfall Substantially below average Substantially below average Below average Below average Normal range Normal range Above average 140% 109% Above average Substantially above average Substantially above average 97% Very wet 120% Very wet

127% 126%

123% 127%

159% 119% 128% 131%

148% 101% 123% 115%

157% 107%

87% 90% 119% 105%

61% 68% 48% 71%

91% 83%

51% 75%

70% 49% 81% 81%

91% 80%

©' NERC (CEH) 2011.© ' Crown copyright. ©' NERC (CEH) 2011.© ' Crown copyright.

Soil Moisture Deficits* March - October 2011 rainfall as % of October 2011 1971-2000 average

SMD (mm) % of average 0 - 10 > 150 10 - 50 130 - 150 50 - 90 110 - 130 90 - 110 90 - 110 70 - 90 110 - 130 60 - 70 130 - 150 50 - 60 Over 150 40 - 50 < 40

©' NERC (CEH) 2011. ©' Crown copyright. * For a grass cover 3 River flow . . . River flow . . . River flow . . . River flow . . .

!(99 Naver

!(125 Ewe Spey !(109 !(120 !(137 Carron Ness !(114 Dee 125 Nevis !( Tay

!(134 Luss 149 March - October Earn J!( !(125 2011 153 124 Tyne !( !( !(109 Whiteadder Clyde !(127 Tweed !(148 South !(124 Nith Tyne Bush !(124 Cree 100 !(114 !( !(121 Eden Camowen 79 !(74 Naver Annacloy !( Lune Derwent 122 !( !(63 !(96 !(95 Wharfe Ribble 127 Ewe Lud !( !(67 Conwy 91 Trent Spey !( 112 121 141 !( Dove 57 !( !( 54 !( !( Witham !(99 !(50 Carron Ness Dee Stringside Soar 41 !(52 Little 73 Severn !( !(52 Ouse !( !(44 Dee J 140 Nevis Wye Teme 35 !( !( 68 Great 65 J 55 Avon !( Colne Tay !( Yscir !( Ouse 59 Teifi !( !(56 Coln Mimram 67 46 !( 124 Cynon !( !(61 !(63 Lee !( !(72 J Luss Earn 155 Lambourn !( !(64!(64 !(61 69 Great Thames !(37 !( !(135 Avon 58 Kennet J Stour !( Medway 62 43 !( !( Tone !(87 Itchen !(60 Tyne !(148 Taw J Ouse 151 63 !( Whiteadder !( 51 102 Stour !( Warleggan !( Clyde Exe !(157 !(62 Kenwyn 52 Tweed J!( !(256 South ©' NERC (CEH) 2011. ©' Crown copyright. J !(163 Nith Tyne Bush !(174 Cree 110 !(113 !( J!(308 Eden Camowen 239 Annacloy !( J Lune Derwent Key 119 !( !(62 !(115 % of long-term average !(118 Wharfe 25 J (record figure when circled) Ribble Lud !(46 !( Exceptionally high flow Conwy Trent !(83 Dove !(35 Notably high flow !(48 Witham !( !(75 !(48 Dee Stringside 19 !( Above normal Severn Soar !(26 !( Little J !(30 Ouse !(40 J !( Normal range Teme 13 Wye !( 53 Great 71 J 44 Avon !( Colne !( Yscir !( Ouse 70 Teifi !( !(29 !( Below normal Coln Mimram 52 42 !( Cynon !( !(44 !(45 Lee !(77 !( Notably low flow Lambourn !(65!(55 !(44 19 44 Great Kennet Thames !( !( !( Exceptionally low flow Avon 48 Stour J!( Medway !(85 !(39 Tone 97 27 Taw !(Itchen Ouse !( Based on ranking of the monthly flow* 72 !( Stour !(33 Warleggan Exe !(98 Kenwyn !(45 October 2011 ©' NERC (CEH) 2011. ©' Crown copyright.

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 im- permeable catchments where the natural variation in flows is much greater. Note: the period of record on which these percentages are based varies from station to station. Percentages may be omitted where flows are under review.

4 River flow . . . River flow . . . River flow . . . River flow . . .

Great Britain 2010/2011 England and Wales 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 600021 Daily mean flows Station No: 600041 Daily mean flows + extreme daily flows (1961 to 2011) + extreme daily flows (1961 to 2011)

Scotland 2010/2011 Northern Ireland 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 600061 Daily mean flows Station No: 600081 Daily mean flows + extreme daily flows (1961 to 2011) + extreme daily flows (1980 to 2011)

Ewe at Poolewe 2010/2011 Tay at Ballathie 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 094001 Daily mean flows Station No: 015006 Daily mean flows + extreme daily flows (1970 to 2011) + extreme daily flows (1952 to 2011)

Clyde at Daldowie 2010/2011 Derwent at Buttercrambe 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 084013 Daily mean flows Station No: 027041 Daily mean flows + extreme daily flows (1963 to 2011) + extreme daily flows (1973 to 2011)

Camowen at Camowen Terrace 2010/2011 Bush at Seneirl Bridge 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 201005 Daily mean flows Station No: 204001 Daily mean flows + extreme daily flows (1972 to 2011) + extreme daily flows (1972 to 2011)

River flow hydrographs

The river flow hydrographs show the daily mean flows together with the maximum and minimum daily flows prior to November 2010 (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 2010/2011 Trent at Colwick 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 076007 Daily mean flows Station No: 028009 Daily mean flows + extreme daily flows (1967 to 2011) + extreme daily flows (1958 to 2011)

Severn at Bewdley 2010/2011 Lud at Louth 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 054001 Daily mean flows Station No: 029003 Daily mean flows + extreme daily flows (1921 to 2011) + extreme daily flows (1968 to 2011)

Teifi at Glan Teifi 2010/2011 Colne at Lexden 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 062001 Daily mean flows Station No: 037005 Daily mean flows + extreme daily flows (1959 to 2011) + extreme daily flows (1959 to 2011)

Cynon at Abercynon 2010/2011 Thames at Kingston 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 057004 Daily mean flows Station No: 039001 Daily mean flows + extreme daily flows (1957 to 2011) + extreme daily flows (1883 to 2011)

Stour at Throop 2010/2011 Itchen at Highbridge+Allbrook 2010/2011 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 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Station No: 043007 Daily mean flows Station No: 042010 Daily mean flows + extreme daily flows (1973 to 2011) + extreme daily flows (1958 to 2011)

Notable runoff accumulations (a) September - October 2011, (b) March - October 2011 River %lta Rank River %lta Rank River %lta Rank a) Ness 154 38/39 b) Tay 134 57/59 b) Tone 43 1/51 Earn 179 64/64 Trent 54 2/53 Brue 38 1/46 Forth 159 30/31 Dove 50 2/50 Severn 44 1/90 Torne 51 2/41 Mole 51 1/36 Teme 35 1/41 Soar 34 2/41 Medway 37 1/49 Wye 46 1/75 Little Ouse 38 2/42 Stour 51 2/39 Luss 125 32/33 Coln 50 2/48 Otter 58 1/49 Nevis 125 28/29 Avon (Amesbury) 53 2/47 Warleggan 62 2/42 Bush 148 36/38 Clyde (Blairston) 172 51/52 Kenwyn 52 1/43 lta = long term average Camowen 236 40/40 Rank 1 = lowest on record Mourne 205 30/30 6 Groundwater . . . Groundwater

Dalton Holme Therfield Rectory 100.0 100.0

20.0 20.0 90.0 90.0

15.0 15.0 80.0 80.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 34.50 Measuring level : 154.81 10.0 10.0 70.0 70.0 2008 2009 2010 2011 2008 2009 2010 2011 Well No: SE94/5 Aquifer: Chalk Well No: TL33/4 Aquifer: Chalk + extremes & mean monthly levels (1889-2007) + extremes & mean monthly levels (1883-2007)

Stonor Park Tilshead 100.0 100.0

90.0 90.0

80.0 80.0 90.0 90.0

70.0 70.0 Water Level ( mOD ) Water Level ( mOD ) Measuring level : 99.88 Measuring level : 121.29 80.0 80.0 60.0 60.0 2008 2009 2010 2011 2008 2009 2010 2011 Well No: SU78/45A Aquifer: Chalk Well No: SU04/2 Aquifer: Chalk + extremes & mean monthly levels (1961-2007) + extremes & mean monthly levels (1966-2007)

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

2008 2009 2010 2011 2008 2009 2010 2011 Well No: SU17/57 Aquifer: Chalk Well No: TQ25/13 Aquifer: Chalk + extremes & mean monthly levels (1932-2007) + extremes & mean monthly levels (1942-2007)

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

2008 2009 2010 2011 2008 2009 2010 2011 Well No: SU01/5B Aquifer: Chalk Well No: SU81/1 Aquifer: Chalk + extremes & mean monthly levels (1942-2007) + extremes & mean monthly levels (1836-2007)

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

2008 2009 2010 2011 2008 2009 2010 2011 Well No: ID30/1 Aquifer: Chalk Well No: TF03/37 Aquifer: Lincolnshire Limestone + extremes & mean monthly levels (1985-2007) + extremes & mean monthly levels (1939-2007)

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 and, for some index wells, the greater frequency of contemporary measurements may, in itself, contribute to an increased range of variation. The latest recorded levels are listed overleaf.

7 Groundwater . . . Groundwater

Ampney Crucis Newbridge

12.0 12.0 102.0 102.0

100.0 100.0 10.0 10.0

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

2008 2009 2010 2011 2008 2009 2010 2011 Well No: SP00/62 Aquifer: Middle Jurassic Well No: NX97/2 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1958-2007) + extremes & mean monthly levels (1993-2007)

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

2008 2009 2010 2011 2008 2009 2010 2011 Well No: NY63/2 Aquifer: Permo-Triassic sandstone Well No: NZ21/29 Aquifer: Magnesian Limestone + extremes & mean monthly levels (1978-2007) + extremes & mean monthly levels (1969-2007)

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 2008 2009 2010 2011 2008 2009 2010 2011 Well No: SE44/80 Aquifer: Magnesian Limestone Well No: SJ15/13 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1979-2007) + extremes & mean monthly levels (1972-2007)

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 2008 2009 2010 2011 2008 2009 2010 2011 Well No: SJ62/112 Aquifer: Permo-Triassic sandstone Well No: SK00/41 Aquifer: Permo-Triassic sandstone + extremes & mean monthly levels (1939-2007) + extremes & mean monthly levels (1974-2007)

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 2008 2009 2010 2011 2008 2009 2010 2011 Well No: SX99/37B Aquifer: Permo-Triassic sandstone Well No: SK15/16 Aquifer: Carboniferous Limestone + extremes & mean monthly levels (1971-2007) + extremes & mean monthly levels (1974-2007)

Groundwater levels October / November 2011 Borehole Level Date Oct av. Borehole Level Date Oct av. Borehole Level Date Oct av. Dalton Holme 12.60 24/10 14.90 Chilgrove House 34.83 31/10 42.28 Brick House Farm 11.47 18/10 12.27 Therfield Rectory 76.70 01/11 79.10 Killyglen (NI) 116.87 31/10 114.77 Llanfair DC 78.99 15/10 79.58 Stonor Park 63.93 01/11 73.15 New Red Lion 7.21 21/10 11.58 Heathlanes 60.57 31/10 61.93 Tilshead 78.41 31/10 80.80 Ampney Crucis 99.78 01/11 100.44 Nuttalls Farm 129.07 31/10 129.67 Rockley 128.64 01/11 130.71 Newbridge 10.53 01/11 9.67 Bussels No.7a 23.28 06/11 23.52 Well House Inn 88.53 01/11 93.08 Skirwith 130.29 31/10 130.02 Alstonfield 175.62 26/10 181.31 West Woodyates 68.97 31/10 74.88 Swan House 81.41 20/10 81.89 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 !(18/19 Magnesian Limestone Killyglen 26/27 !( Swan House Permo-Triassic sandstones Skirwith !(23/27 !(15/41 Jurassic limestones Wetwang Chalk !(5/41 Brick House !(9/32 !(10/123 Farm Dalton Holme !(8/34

Alstonfield Aylesby !(4/39 !(11/38 Llanfair !(5/48 Washpit D.C. 4/41 !( !(12/61 Farm New Red Lion Heathlanes !(11/37 Dial Redlands Nuttalls Farm Hall Farm !(11/41 Therfield !(5/45 Ampney Rectory 40/124 Crucis !(

!(11/51 Stonor !(7/50 Park Rockley 2/79 !( Well !(6/67 House Little West dry Tilshead 5/39 !( Chilgrove Inn !( Bucket Lime WoodyateJs Compton House Houndean Farm Kiln Manor 8/64 House 3/176 9/34 Bussels Way !( !(11/116 !( !( 8/42 No 7A !(5/39 !( !(19/71 Westdean No 3 !(4/38 Ashton Farm

'© NERC 2011. '© Crown copyright.

Groundwater levels - October 2011 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 reservoir stocks for England and and Wales Wales in recent years

25 100

20 90 15

10 80 5

0 70

−5 60 −10

−15 Percentage live capacity 1988−2010 mean 50 1995−1996 −20 2003−2004 % devn. from 1988−2010 monthly mean 2009−2010 2010−2011 −25 40 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Nov Dec Jan Feb Mar Apr May JunJul Aug Sep Oct

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

Capacity 2011 Nov Min Year* 2010 Diff Area Reservoir (Ml) Sep Oct Nov Anom. Nov of min Nov 11-10 North West N Command Zone • 124929 66 78 80 14 33 2003 70 10 Vyrnwy 55146 77 86 75 1 25 1995 79 -4 Northumbrian Teesdale • 87936 91 93 91 18 33 1995 86 5 Kielder (199175) (93) (91) (90) 4 63 1989 89 1 Severn Trent Clywedog 44922 80 87 86 10 38 1995 85 1 Derwent Valley • 39525 56 53 75 4 15 1995 70 5 Yorkshire Washburn • 22035 69 71 81 13 15 1995 75 6 Bradford supply • 41407 73 76 86 15 16 1995 70 16 Anglian Grafham (55490) (90) (89) (84) 2 44 1997 95 -11 Rutland (116580) (73) (70) (66) -11 59 1995 75 -9 Thames London • 202828 86 80 69 -8 46 1996 89 -20 Farmoor • 13822 98 93 85 -4 43 2003 99 -14 Southern Bewl 28170 57 50 43 -17 33 1990 48 -5 Ardingly 4685 61 48 34 -32 15 2003 68 -34 Wessex Clatworthy 5364 49 37 33 -29 14 2003 36 -3 Bristol WW • (38666) (62) (57) (53) -8 24 1990 50 3 South West Colliford 28540 50 48 49 -21 38 2006 75 -26 Roadford 34500 53 54 56 -15 18 1995 67 -11 Wimbleball 21320 47 44 44 -23 26 1995 51 -7 Stithians 4967 51 44 39 -17 18 1990 51 -12 Welsh Celyn and Brenig • 131155 94 96 93 10 48 1989 94 -1 Brianne 62140 94 98 100 9 57 1995 97 3 Big Five • 69762 76 85 93 19 38 2003 92 1 Elan Valley • 99106 83 90 100 15 37 1995 84 16

Scotland(E) Edinburgh/Mid Lothian • 97639 91 97 100 20 48 2003 79 21 East Lothian • 10206 100 100 100 18 38 2003 98 2 Scotland(W) Loch Katrine • 111363 92 96 95 10 40 2003 93 2 Daer 22412 99 99 100 10 42 2003 99 1 Loch Thom • 11840 96 95 100 11 66 2007 95 5

Northern Total+ • 56920 72 78 93 13 39 1995 87 6 Ireland Silent Valley • 20634 66 73 88 15 34 1995 89 -1 () 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 1988-2010 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. © NERC (CEH) 2011. 10 Location map . . . Location map

gauging station Naver groundwater index well 25 100 reservoir - individual 20 90 reservoir - group (general location only) 15 Ewe 10 80 5 Chalk Carron Deveron Spey Jurassic limestones 0 70 Ness

−5 Permo-Triassic sandstones 60 −10 Dee Magnesian Limestone Nevis −15 Percentage live capacity 1988−2010 mean Minor aquifers (including the Carboniferous 50 1995−1996 −20 2003−2004 % devn. from 1988−2010 monthly mean 2009−2010 Limestone) have been omitted. 2010−2011 Tay −25 40 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Nov Dec Jan Feb Mar Apr May JunJul Aug Sep Oct 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 Aylesby Don Torne Derwent Valley Conwy Morris Dancers Lud Witham Llyn Llanfair D.C Dover Beck Brenig Alstonfield 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 Twyi 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 Test Inn West Compton Medway Great Stour Wimbleball Clatworthy Lym Ardingly Taw Woodyates House Ouse Exe Brue Bewl Water Stour ington Chilgrove Tone Itchen Piddle House Houndean Roadford OtterLime Kiln Way Wallington Bussels Westdean No.3 No.7A Ashton Farm Colliford Dart arleggan Kenwyn W Stithians

©NERC (CEH, BGS) 2011. © Crown copyright.

11 National Hydrological Monitoring Programme

The National Hydrological Monitoring Programme For further details please contact: (NHMP)# is undertaken jointly by the Centre for Ecol- ogy & Hydrology (CEH) and the British Geological The Met Office Survey (BGS). Financial support for the production of FitzRoy Road the monthly Hydrological Summaries is provided by the Exeter Department for Environment, Food and Rural Affairs Devon (Defra), the Environment Agency (EA), the Scottish EX1 3PB Environment Protection Agency (SEPA), the Rivers Agency (RA) in Northern Ireland, and the Office of Water Tel.: 0870 900 0100 Fax: 0870 900 5050 Services (OFWAT). E-mail: [email protected]

Data Sources The National Hydrological Monitoring Programme de- River flow and groundwater level data are provided by the pends on the active cooperation of many data suppliers. Environment Agency, the Environment Agency Wales, This cooperation is gratefully acknowledged. the Scottish Environment Protection Agency and, for Northern Ireland, the Rivers Agency and the Northern Ireland Environment Agency. In all cases the data are subject to revision following validation (flood and drought data in particular may be subject to significant revision). Enquiries Reservoir level information is provided by the Water Enquiries should be addressed to: Service Companies, the EA, Scottish Water and Northern Ireland Water. Hydrological Summaries for the UK Centre for Ecology & Hydrology The National River Flow Archive (maintained by CEH) Maclean Building and the National Groundwater Level Archive (maintained Crowmarsh Gifford by BGS) provide the historical perspective within which Wallingford to examine contemporary hydrological conditions. Oxfordshire OX10 8BB Rainfall Most rainfall data are provided by the Met Office (see op- Tel.: 01491 838800 posite). To allow better spatial differentiation the rainfall Fax: 01491 692424 data for Britain are presented for the regional divisions of E-mail: [email protected] the precursor organisations of the EA and SEPA. Follow- ing the discontinuation of the Met Office’s CARP system in July 1998, the areal rainfall figures have been derived Selected text and maps are available on the WWW at using several procedures, including initial estimates based http://www.ceh.ac.uk/data/nrfa/nhmp/nhmp.html on MORECS*. Recent figures have been produced by the Navigate via Hydrological Summary for the UK. Met Office, National Climate Information Centre (NCIC), using a technique similar to CARP. A significant number of additional monthly raingauge totals are provided by the EA and SEPA to help derive the contemporary regional rainfalls. Revised monthly national and regional rainfall Some of the features displayed on the maps contained in this report are based on the following data with permission totals for the post-1960 period were made available by of the controller of HMSO. the Met Office in 2004; these have been adopted by the (i) Ordnance Survey data. © Crown copyright and/or da- NHMP. As with all regional figures based on limited tabase right 2005. Licence no. 100017897. raingauge networks the monthly tables and accumulations (ii) Land and Property Services data. © Crown copyright (and the return periods associated with them) should be and database right, S&LA 145. regarded as a guide only. (iii) Met Office rainfall data. © Crown copyright. The monthly rainfall figures are provided by the Met Of- All rights reserved. Unauthorised reproduction infringes fice (National Climate Information Centre) and are Crown crown copyright and may lead to prosecution or civil Copyright and may not be passed on to, or published by, proceedings. any unauthorised person or organisation. Text and maps in this document are © NERC (CEH) 2011 # Instigated in 1988 * unless otherwise stated and may not be reproduced without MORECS is the generic name for the Met Office services permission. involving the routine calculation of evaporation and soil moisture throughout Great Britain.

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