Monthly Water Situation Report Yorkshire Area

Monthly water situation report Yorkshire Area

Summary – November 2018 An unsettled month with average or above average monthly rainfall being common. Low flows dominated early November which rose into the higher flow range by the end of the month. The soils became wetter and returned to more normal conditions expected for the time of year, groundwater levels were generally falling, and overall reservoir stocks still remained below their long term average.

Rainfall November was another month dominated by unsettled conditions with the majority of the Area recording average or above average monthly rainfall. The exception being the upper reaches of the catchments immediately adjacent to the Pennine ridge where below average monthly totals were common.

Although there were few dry days throughout November, the first half to the month received many days of low intensity, low daily total rainfall and was on the way to record below average monthly rainfall. Then the second half of the month saw more days containing higher rainfall totals, with the last four days in particular seeing some significant rainfall over Yorkshire.

Despite the more average monthly rainfall for the month, with using the NCIC [National Climate Information Centre] Met Office dataset from 1910, it is showing that the 7-month period ending in November was the 2nd driest for the River Aire catchment, the 3rd driest for the River Calder catchment, and the 6th driest for the River Esk & North Sea catchment.

Soil Moisture Deficit [SMD] High SMD was experienced at the start of November and the majority of Yorkshire’s soils were classed as being in the ‘dry’ range. The exception to this were the areas immediately adjacent to the Pennine ridge which were classed to be within the ‘normal’ or ‘wet’ range. As conditions became wetter through the month, the SMD reduced and by the end of the month all of Yorkshire had returned to conditions that were classed as being more normal for the time of year.

River Flows Low river flows were prominent within the Pennine fed catchments during the first half of November and many of the rivers were at a level below what would normally be expected for the time of year. During the second half of the month, and especially during the last few days as more significant rain fell, the rivers began to rise and there were many locations that had flows above what would normally be expected for the time of year. With regards to the monthly mean flows, as shown in the map below, the majority of catchments were experiencing flows below what would normally be expected for the time of year.

In the groundwater dominated catchments in the east of the area, the rivers showed a similar response to those in the Pennine fed catchments. The rivers fluctuated around lower flow conditions during the first half of the month before rising during the second half. When looking at the monthly mean flows, West Beck, located in the upper River Hull catchment, and the River Derwent were experiencing flows that would normally be expected for the time of year.

Groundwater Levels Magnesian Limestone The groundwater level at Brick House Farm had continued to decline and was below the average for the time of year.

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 2018

Millstone Grit The groundwater level at Hill Top Farm was below average for the time of year.

Sherwood Sandstone The groundwater level in the north of the Sherwood Sandstone was at a similar level to the previous month and above the average for the time of year. The level in the south of the aquifer continued to increase and reached the average for the time of year.

Corallian Limestone The groundwater level at Sproxton decreased slightly and was still below the average level for the time of year. It had also reached its drought trigger level.

Chalk The groundwater level in the northern area of the aquifer, as monitored at Wetwang, decreased slightly and was below the average level for the time of year. At Dalton Estate in the south of the aquifer the groundwater level continued to decline and was just below the average for the time of year.

Reservoir Storage The reservoir stocks showed a slight decline through the first half of the month as low intensity rainfall dominated. But once the more significant rain arrived, the reservoirs started to show some improvement and began to rise. However, by the end of November overall reservoir stocks were still 26% below the LTA.

Environmental Impact By the end of November, there were 2 Hands Off Flow (HOF) licences in force located in the Hull & Humber catchment. A further 27 advance warning letters had been sent that were distributed throughout the Area.

Author: Yorkshire Hydrology

Rainfall

Above average rainfall Below average rainfall 1-Month Period for Swale (NE) 1-Month Period for Ure 200% 150%

150%

100%

50%

0% 0% Dec-17 Mar-18 Jun-18 Sep-18 Dec-17 Mar-18 Jun-18 Sep-18

1-Month Period for Nidd 1-Month Period for Ouse 200% 200%

150% 150%

100% 100%

50% 50%

0% 0% Dec-17 Mar-18 Jun-18 Sep-18 Dec-17 Mar-18 Jun-18 Sep-18

1-Month Period for Wharfe 1-Month Period for Dales North Sea Tribs 200% 250%

200% 150%

150%

100%

50% 50%

0% 0% Dec-17 Mar-18 Jun-18 Sep-18 Dec-17 Mar-18 Jun-18 Sep-18

1-Month Period for Rye 1-Month Period for Derwent (NE) 200% 300%

250% 150% 200%

100% 150%

100% 50% 50%

0% 0% Dec-17 Mar-18 Jun-18 Sep-18 Dec-17 Mar-18 Jun-18 Sep-18

Above average rainfall Below average rainfall 1-Month Period for Aire 1-Month Period for Calder 200% 200%

150% 150%

100% 100%

50% 50%

0% 0% Dec-17 Mar-18 Jun-18 Sep-18 Dec-17 Mar-18 Jun-18 Sep-18

1-Month Period for Don 1-Month Period for Hull and Humber 250% 300%

250% 200%

200% 150%

150%

100% 100%

50% 50%

0% 0% Dec-17 Mar-18 Jun-18 Sep-18 Dec-17 Mar-18 Jun-18 Sep-18

Soil Moisture Deficit

River Flow

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Birstwith, NIDD Buttercrambe, DERWENT (NE) Ranking derived from data for the period Dec-1976 to Dec-2012 Ranking derived from data for the period Sep-1973 to Dec-2012

20 50 18 45 16 40 14 35 12 30 10 25 8 20

Flow (cumecs) Flow 6 (cumecs) Flow 15 4 10 2 5 0 0 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Crakehill Topcliffe, SWALE (NE) Doncaster, DON (NE) Ranking derived from data for the period May-1980 to Dec-2012 Ranking derived from data for the period Jul-1959 to Dec-2012

70 60 60 50 50

40 40

30 30

Flow (cumecs) Flow 20 (cumecs) Flow 20

10 10

0 0 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18

Elland, CALDER (NE) Hunsingore, NIDD Ranking derived from data for the period Jun-1971 to Dec-2012 Ranking derived from data for the period Oct-1968 to Dec-2012

35 25

30 20 25 15 20

15 10 Flow (cumecs)Flow (cumecs)Flow 10 5 5

0 0 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18

Kildwick, AIRE Kilgram Bridge, URE Ranking derived from data for the period Jul-1971 to Dec-2012 Ranking derived from data for the period Jul-1971 to Dec-2012

60 25

50 20 40 15 30 10 20 Flow (cumecs) Flow (cumecs) Flow

5 10

0 0 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18

Kirby Wiske, WISKE Skelton, OUSE (NE) Ranking derived from data for the period Mar-1980 to Dec-2012 Ranking derived from data for the period Sep-1969 to Dec-2012

25 160 20 140 120 15 100 80 10 60 Flow (cumecs)Flow (cumecs)Flow 5 40 20 0 0 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18

Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Tadcaster, WHARFE Wansford Snakeholm Lock - West Beck, WEST BECK Ranking derived from data for the period Jun-1991 to Dec-2012 Ranking derived from data for the period Oct-1988 to Dec-2012

60 7

50 6

40 5 4 30 3

Flow (cumecs) Flow 20 (cumecs) Flow 2

10 1

0 0 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18

Whittington, ROTHER Addingham, WHARFE Ranking derived from data for the period Nov-1979 to Dec-2012 Ranking derived from data for the period Dec-1973 to Dec-2012

7 70 6 60 5 50 4 40

3 30

Flow (cumecs)Flow 2 (cumecs)Flow 20

1 10

0 0 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18

Walden Stubbs, WENT Ranking derived from data for the period Nov-1979 to Dec-2012

1 Flow (cumecs) Flow

0 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18 Dec-18

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 Dec-2012 Ranking derived from data for the period Jan-1889 to Dec-2012

18 22 17

16 20

15 18 14 16 13 14 Level (mAOD) Level 12 (mAOD) Level

11 12

10 10 Feb-16 Jun-16 Oct-16 Feb-17 Jun-17 Oct-17 Feb-18 Jun-18 Oct-18 Feb-16 Jun-16 Oct-16 Feb-17 Jun-17 Oct-17 Feb-18 Jun-18 Oct-18

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 Dec-2012 Ranking derived from data for the period Oct-1973 to Dec-2012

17 127

17 127 16 126 16

15 126

15 125 Level (mAOD) Level 14 (mAOD) Level 125 14

13 124 Feb-16 Jun-16 Oct-16 Feb-17 Jun-17 Oct-17 Feb-18 Jun-18 Oct-18 Feb-16 Jun-16 Oct-16 Feb-17 Jun-17 Oct-17 Feb-18 Jun-18 Oct-18

Riccal Approach Fm Sproxton Ranking derived from data for the period Feb-1977 to Dec-2012 Ranking derived from data for the period Oct-1972 to Dec-2012

7 51 7 50 6 49 6 48 5 47 5 46 4 45

Level (mAOD) Level 4 (mAOD) Level 3 44 3 43 2 42 Feb-16 Jun-16 Oct-16 Feb-17 Jun-17 Oct-17 Feb-18 Jun-18 Oct-18 Feb-16 Jun-16 Oct-16 Feb-17 Jun-17 Oct-17 Feb-18 Jun-18 Oct-18

Wetwang Ranking derived from data for the period Oct-1971 to Dec-2012

Level (mAOD) Level 21

17 Feb-16 Jun-16 Oct-16 Feb-17 Jun-17 Oct-17 Feb-18 Jun-18 Oct-18

Reservoir Stocks – Data from Water Company

Yorkshire Supply (data supplied by Water Company) 100

80 Weekly 70 LTA (historic)

60 Maximum (historic) Minimum (historic) 50

30 Percentage of live capacity

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).