Water Situation Report Yorkshire Area

Monthly water situation report Yorkshire Area

Summary – February 2020 A persistently wet month with well above average rainfall across the area. River flows were in the exceptionally or notably high range and new record monthly mean flows for February were set on the Pennine fed rivers. Soils remained saturated throughout the month. Groundwater levels increased in all aquifers, and set new maximum observed levels at monitoring locations in the Millstone Grit and parts of the Sherwood Sandstone. Reservoirs were close to full capacity throughout the month.

Rainfall Yorkshire experienced extremely wet weather during February. The Pennine fed catchments of the Swale, Ure, Nidd, Wharfe, Aire, Calder and Don received between 320% and 375% of the monthly Long Term Average (LTA) rainfall. The lower Ouse, Rye, Derwent and Hull further east received between 245% and 295% of the LTA.

Most days in February were wet apart from a brief settled period from the 4th to the 6th. The three most significant rainfall episodes were:  the 8th to 9th February, named Storm Ciara. Heavy rainfall associated with a frontal weather system was widespread across Yorkshire, with bands of particularly intense rainfall along the Pennine Ridge. Locations in the Aire, Calder and upper Nidd catchments received 106% to 128% of the February LTA in 48 hours.  the 15th to 16th February, named Storm Dennis. Widespread rainfall on the afternoon of the 15th, followed by two phases of intense rainfall particularly over the lower reaches of the Dales catchment and the Don valley. 60% to 80% of the February LTA was recorded at many locations over 48 hours, increasing to over 90% near the east coast where the background LTA values are more modest.  The 21st to 24th February. A prolonged and fairly static area of heavy rainfall over the upper Dales catchments on the 21st, with further spells of rain crossing the region on the 22nd and 23rd. Some snowfall and rapid snowmelt occurred on the 24th. Although rainfall was less intense than the above two named storms, this four day period produced significant depths of precipitation over the Pennine catchments.

Storms Ciara and Dennis together produced between 30% and 50% of February 2020’s recorded rainfall at most sites. When the 21st to 24th February totals are added, these three periods accounted for 60% to 70% of the month’s recorded rainfall.

Using the Met Office Had-UK dataset, with records commencing in 1891, February 2020 was the wettest February on record in the Swale, Ure, Nidd, Wharfe, Aire, Calder and Don catchments. It was the second wettest in the Hull and Ouse catchments and the third wettest in the Derwent.

Soil Moisture Deficit Across the Yorkshire area, SMD was zero or very close to zero throughout the month. All catchment soils were classified as Wet, representing saturated conditions.

River Flows Monthly mean river flows during February were in the notably high to exceptionally high range in almost all Yorkshire’s major catchments, reflecting the wet weather conditions. The Pennine fed rivers recorded between 275% and 375% of the LTA, while the Rye, Derwent and Esk recorded between 140% and 165% of the LTA. Only the Chalk-fed West Beck in the upper River Hull catchment recorded monthly mean flows in the normal range, at 129% of the LTA. The highest February monthly mean flows on record were achieved at many locations, namely within the Swale, Ure, Nidd, Ouse, Wharfe, Aire, Calder, Don and Rother catchments.

All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained herein. © Environment Agency 2020

Up to the 8th February, flows in the Pennine fed catchments were mostly in the normal range, although the Swale, Ure and Aire had a brief period of higher flows within the 1st to the 3rd of the month. With the arrival of Storm Ciara, flows rose quickly across all catchments on the 9th, producing sharp flood peaks on the 9th or 10th. Flows remained in the above normal to exceptionally high range for the remainder of the month, with further flow peaks occurring on the 16th or 17th after Storm Dennis and multiple peaks between the 22nd and 25th.

Significant river level peaks were recorded on the upper Dales rivers on the 9th and 10th February, following Storm Ciara. The 2nd to 5th ranked peaks on record occurred on the Swale, Ure, Nidd and Wharfe at locations with between 25 and 48 years of record. On the upper Aire at Gargrave, the highest river level in 43 years was recorded. In the Calder catchment the peak ranked highest on record at Dewsbury (in 23 years) and Colne Bridge (in 54 years), and second highest at Hebden Bridge, Mytholmroyd and Elland. Peak river levels associated with Storm Dennis the following week were generally lower, except on the Rivers Don and Rother and on the lower Swale. The Don at Doncaster recorded its fifth highest level in 43 years during this event.

In addition to the peak flows, the last three weeks of February featured large volumes of baseflow passing out of the Dales to the lowland river reaches and floodplains, as persistent rainfall did not allow river flows to recede fully between peaks. This was particularly noticeable on the lower Swale and River Ouse.

Flows in the River Derwent were in the below normal range until 8th February, then rose quickly on the 9th to a peak on the 10th to 11th, with sustained high flows for the remainder of the month, including a further peak from the 17th to the 18th. Flows in the River Rye showed a similar pattern.

Flows in the River Esk in the north-east of the area were exceptionally low during the first week of the month. Flows increased rapidly in response to rainfall, with a peak occurring on the 9th and again on the 16th, the river fluctuating between normal and exceptionally high flow ranges.

In the River Hull in the east of the area, flows for the first half of the month were mostly in the normal range, apart from short duration higher flow peaks on the 9th and the 16th. Flows increased above normal and continued rising from the 17th to the 25th, becoming steady for the last few days of the month. A similar pattern was observed on Mires Beck, with a gradual increase in baseflow through the month.

Groundwater Levels There was a rise in groundwater levels throughout the area due to the large rainfall totals occurring during February. Magnesian Limestone The groundwater level at Brick House Farm rose and equalled the highest previously recorded level for February. Millstone Grit The groundwater level at Hill Top Farm rose to a new maximum level observed at this site (for any month) in a 46 year record. Sherwood Sandstone Groundwater levels in the Sherwood Sandstone increased this month. At Riccall Approach they were well above average for the time of year and at Great Ouseburn they reached a new maximum observed level (for any month) in a 44 year record. Corallian Limestone The groundwater levels at Sproxton & East Ness increased this month and were above average for the time of year. Chalk The groundwater level in the northern area of the aquifer, as monitored at Wetwang, increased and was above average for the time of year. At Dalton Estate in the south of the aquifer the groundwater level remained steady and was well above average for the time of year.

Reservoir Storage Reservoir stocks increased slightly through the month and were at almost full capacity. By month end, overall reservoir stocks were 5% above the LTA (based on records from 1990).

Environmental Impact No Hands off Flow restrictions were in force after the first week of February. In January, twenty-four abstractors had been issued with advance warning notifications of low flows, although they were still able to abstract, and during February flows rose back above the warning threshold at all of these sites.

Author: Yorkshire Hydrology

Rainfall

Above average rainfall Below average rainfall 1-Month Period for Swale (NE) 1-Month Period for Ure

350% 400%

350% 300%

300% 250%

250% 200%

200%

150% 150%

100% 100%

50% 50%

0% 0%

Sep-19 Sep-19 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20

1-Month Period for Nidd 1-Month Period for Ouse

400% 250%

350%

200% 300%

250% 150%

200%

100% 150%

100% 50%

50%

0% 0%

Sep-19 Sep-19 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20

1-Month Period for Wharfe 1-Month Period for Dales North Sea Tribs

400% 250%

350%

200% 300%

250% 150%

200%

100% 150%

100% 50%

50%

0% 0%

Sep-19 Sep-19 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20

1-Month Period for Rye 1-Month Period for Derwent (NE)

250% 250%

200% 200%

150% 150%

100% 100%

50% 50%

0% 0%

Sep-19 Sep-19 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20

Above average rainfall Below average rainfall 1-Month Period for Aire 1-Month Period for Calder

400% 250%

350%

200% 300%

250% 150%

200%

100% 150%

100% 50%

50%

0% 0%

Sep-19 Sep-19 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20

1-Month Period for Don 1-Month Period for Hull and Humber

250% 250%

200% 200%

150% 150%

100% 100%

50% 50%

0% 0%

Sep-19 Sep-19 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20

Soil Moisture Deficit

February 2020

0.00 0.00 0.00

0.00 0.00 0.00 0.00

0.00

River Flow

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Addingham, WHARFE Birstwith, NIDD Ranking derived from data for the period Dec-1973 to Dec-2017 Ranking derived from data for the period Dec-1976 to Dec-2017

60 25

50 20

40 15 30 10

Flow (cumecs)Flow (cumecs)Flow 5 10

0 0 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Briggswath, ESK Buttercrambe, DERWENT Ranking derived from data for the period Jan-1993 to Dec-2017 Ranking derived from data for the period Sep-1973 to Dec-2017

20 50

40 15

30 10

Flow (cumecs)Flow (cumecs)Flow 5 10

0 0 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20

Crakehill Topcliffe, SWALE Doncaster, DON Ranking derived from data for the period Jun-1980 to Dec-2017 Ranking derived from data for the period Jul-1959 to Dec-2017

100 80 90 80 70 70 60 60 50 50 40 40

30 Flow (cumecs)Flow Flow (cumecs)Flow 30 20 20 10 10 0 0 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20

Elland, CALDER Hunsingore, NIDD Ranking derived from data for the period Jul-1971 to Dec-2017 Ranking derived from data for the period Oct-1968 to Dec-2017

40 40 35 35 30 30 25 25 20 20

15 15

Flow (cumecs)Flow (cumecs)Flow 10 10 5 5 0 0 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20

Kildwick, AIRE Kilgram Bridge, URE Ranking derived from data for the period Aug-1971 to Dec-2017 Ranking derived from data for the period Aug-1971 to Dec-2017

70 30 60 25 50 20 40 15

30 Flow (cumecs)Flow Flow (cumecs)Flow 10 20

5 10

0 0 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Ness, RYE Skelton, OUSE Ranking derived from data for the period Sep-1974 to Dec-2017 Ranking derived from data for the period Sep-1969 to Dec-2017

10 200

8 150 6 100

Flow (cumecs)Flow (cumecs)Flow 50 2

0 0 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20

Tadcaster, WHARFE Walden Stubbs, WENT Ranking derived from data for the period Jul-1991 to Dec-2017 Ranking derived from data for the period Oct-1979 to Dec-2017

4.0 70 3.5

60 3.0

50 2.5

40 2.0

30 1.5 Flow (cumecs)Flow Flow (cumecs)Flow 20 1.0

10 0.5

0 0.0 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20

Wansford Snakeholm Lock - West Beck, WEST BECK Whittington, ROTHER Ranking derived from data for the period Nov-1988 to Dec-2017 Ranking derived from data for the period Nov-1979 to Dec-2017

8 10 7

6 8 5 6 4

3 4 Flow (cumecs)Flow Flow (cumecs)Flow 2 2 1

0 0 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20 May-19 Jul-19 Sep-19 Nov-19 Jan-20 Mar-20

Groundwater Levels

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Brick House Fm Dalton Estate Well Ranking derived from data for the period Oct-1979 to Nov-2017 Ranking derived from data for the period Jan-1889 to Nov-2017

18 23

17 21 16 19 15

14 17

15 Level (mAOD) Level Level (mAOD) Level 12 13 11

10 11 May-17 Sep-17 Jan-18 May-18 Sep-18 Jan-19 May-19 Sep-19 Jan-20 May-17 Sep-17 Jan-18 May-18 Sep-18 Jan-19 May-19 Sep-19 Jan-20

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Great Ouseburn Hill Top Fm Ranking derived from data for the period Jan-1976 to Nov-2017 Ranking derived from data for the period Oct-1973 to Nov-2017

17 128

128 17 127 16 127

16 126

126

15 Level (mAOD) Level Level (mAOD) Level 125 15 125

14 124 May-17 Sep-17 Jan-18 May-18 Sep-18 Jan-19 May-19 Sep-19 Jan-20 May-17 Sep-17 Jan-18 May-18 Sep-18 Jan-19 May-19 Sep-19 Jan-20

Riccall Approach Farm Sproxton Ranking derived from data for the period Feb-1977 to Nov-2017 Ranking derived from data for the period May-1975 to Nov-2017

7 50

7 49 6 48 6 5 47 5 46

4 45 Level (mAOD) Level Level (mAOD) Level 4 44 3 3 43 2 42 May-17 Sep-17 Jan-18 May-18 Sep-18 Jan-19 May-19 Sep-19 Jan-20 May-17 Sep-17 Jan-18 May-18 Sep-18 Jan-19 May-19 Sep-19 Jan-20

Wetwang Ranking derived from data for the period Oct-1971 to Nov-2017

33 31 29 27 25

23 Level (mAOD) Level 21 19 17 May-17 Sep-17 Jan-18 May-18 Sep-18 Jan-19 May-19 Sep-19 Jan-20

Reservoir Stocks – Data from Water Company

Yorkshire Supply (data supplied by Water Company) 100

30 Percentage of Percentagelive capacity

Weekly LTA (historic) 10 Maximum (historic) Minimum (historic) 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec This graph is produced from Yorkshire Water © Crown Copyright data.

Glossary

Term Definition

Aquifer A geological formation able to store and transmit water.

Areal average rainfall The estimated average depth of rainfall over a defined area. Expressed in depth of water (mm).

Artesian The condition where the groundwater level is above ground surface but is prevented from rising to this level by an overlying continuous low permeability layer, such as clay.

Artesian borehole Borehole where the level of groundwater is above the top of the borehole and groundwater flows out of the borehole when unsealed.

Cumecs Cubic metres per second (m3s-1)

Effective rainfall The rainfall available to percolate into the soil or produce river flow. Expressed in depth of water (mm).

Flood Alert/Flood Warning Three levels of warnings may be issued by the Environment Agency. Flood Alerts indicate flooding is possible. Flood Warnings indicate flooding is expected. Severe Flood Warnings indicate severe flooding.

Groundwater The water found in an aquifer.

Long term average (LTA) The arithmetic mean calculated from the historic record, usually based on the period 1961-1990. However, the period used may vary by parameter being reported on (see figure captions for details). mAOD Metres Above Ordnance Datum (mean sea level at Newlyn Cornwall).

MORECS Met Office Rainfall and Evaporation Calculation System. Met Office service providing real time calculation of evapotranspiration, soil moisture deficit and effective rainfall on a 40 x 40 km grid.

Naturalised flow River flow with the impacts of artificial influences removed. Artificial influences may include abstractions, discharges, transfers, augmentation and impoundments.

NCIC National Climate Information Centre. NCIC area monthly rainfall totals are derived using the Met Office 5 km gridded dataset, which uses rain gauge observations.

Recharge The process of increasing the water stored in the saturated zone of an aquifer. Expressed in depth of water (mm).

Reservoir gross capacity The total capacity of a reservoir.

Reservoir live capacity The capacity of the reservoir that is normally usable for storage to meet established reservoir operating requirements. This excludes any capacity not available for use (e.g. storage held back for emergency services, operating agreements or physical restrictions). May also be referred to as ‘net’ or ‘deployable’ capacity.

Soil moisture deficit (SMD) The difference between the amount of water actually in the soil and the amount of water the soil can hold. Expressed in depth of water (mm).