Monthly water situation report

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Monthly water situation report

Summary – September 2018

Rainfall was in the ‘normal’ range for all catchments this month, although 60% of the monthly total fell on a single day. River flows were categorised as ‘normal’ in all catchments with the exception of the Coquet where flows were categorised as ‘below normal’. Soils have become wetter, particularly in the upper catchments of Tyne, Tees and Wear, but remain dry in the northern and south-western catchments.

Groundwater levels have slightly declined but remain healthy. Reservoir stocks have increased slightly in several reservoirs, although all stocks except the Lune Balder Group remain below average for the time of year.

Rainfall

September monthly rainfall is classed as ‘normal’ for all catchments, with monthly totals ranging from 78% of the long term average (LTA) in the Seaham, Peterlee Coastal Area to 116% of the LTA in the Tweed catchment.

Monthly rainfall totals have been below the LTA for the 5th consecutive month in four of the six North East catchments: the Northumbria North Sea Tribs, Wear, Tees and Seaham, Peterlee Coastal Areas. Some parts of the area have now recorded prolonged dry periods, for example in the Tees catchment rainfall is ‘notably low’

over the past 6 and 12 months.

In general there were more dry days (ranging from 16 – 25 days) in September in comparison to August, with rainfall recorded during a few small sporadic showers. A notable event, affecting most catchments, occurred on the 20th September. During this event, larger daily rainfall totals of 25-33mm were recorded, accounting for approximately 60% of the month’s rainfall. The last week of the month was predominantly dry with less than 1mm recorded in most areas.

Soil Moisture Deficit

Soils have become wetter in parts of the Area, particularly in the upper Tyne, upper Tees and upper Wear catchments. The northern and south western catchments remain ‘dry’ and the Northumbria Sea Tribs area has changed from ‘dry’ to ‘very dry’.

River Flows

Monthly river flows remain ‘normal’ in all but the River Coquet catchment, where flows have remained ‘below normal’. Flows in the River Till increased in response to wetter conditions, changing from ‘exceptionally low’ to

‘normal’. For the 5th consecutive month flows across all catchments were below the LTA, ranging from 24% in River Blyth at Hartford Bridge to 97% in the River Tees at Middleton in Teesdale.

Daily mean flows tended to fluctuate around the ‘normal’ and ‘below normal’ category throughout the month.

Flows in the River Till at Heaton Mill remained ‘below normal’ to ‘exceptionally low’ throughout the majority of the month, only rising to ‘above normal’ on the 20^th. High flows were recorded around 20^th and 21^st September across the area, in response to the rainfall event which resulted in all catchments entering either the ‘above normal’ or

‘exceptionally high’ category for two or three days. By the end of the month flows across the area had returned to

‘notably low’ or ‘below normal’.

Groundwater Levels

Groundwater levels across the North East area’s aquifers range from ‘below normal’ to ‘notably high’ this month.

Groundwater levels in the unconfined area of the Magnesian Limestone aquifer, represented by the responsive Aycliffe borehole, show a further decrease as part of a continuing downward trend over the last four months.

North East Area

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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.

www.gov.uk/environment-agency © Environment Agency 2018 2 This site monitors water levels continuously and has a slower response time than the unconfined area, with recent ‘normal’ rainfall amounts in the catchment unlikely to have reached this part of the aquifer yet. The

confined area of the Magnesian Limestone, represented by the relatively slowly responding borehole at Red Lion, shows a slight decrease following a recent upward trend. In spite of this, levels are ‘notably high’ here. This recent decline suggests that the high rainfall amounts recorded in mid-2017 have now reached and are passing through this part of the aquifer.

Groundwater levels in the Fell Sandstone have seen another, sharper decline in the semi-confined area, represented by Royalty Observation, as part of a continuing downward trend following on from a sharp increase in April. Although levels have dropped, in-line with ‘below normal’ rainfall in the Till/Tweed catchment during the preceding three months, they remain ‘above normal’ in this part of the aquifer. Unconfined areas of the Fell Sandstone aquifer, represented by Townlaw, have seen a slight decrease in groundwater level and are now classed as ‘below normal’. This borehole is considered to be very responsive to rainfall and with the dip reading was taken on 28^th September, with very low amounts of rainfall recorded in the catchment in the preceding week, any rainfall is likely to have been reflected prior to the GW being measured.

Reservoir Storage

Kielder, the Durham Group, the Lune Balder Group and Cow Green have shown a slight increase in stocks this month. The remaining reservoirs declined slightly through September by 3-5%. All stocks except the Lune Balder group remain between 5-20% below the average for the time of the year. Stocks in Waskerley reservoir

continued to be supported through the month by transfers from the Tyne-Tees Tunnel. Abstractions from the North Tyne at Barrasford continued to support levels in West Hallington reservoir and releases began from the Tyne-Tees tunnel to the River Derwent from 4^th September to conserve stocks in Derwent Reservoir.

Current % Stocks Previous Month % Stock

Kielder 80 78

North Tynedale Group 51 54

Derwent 55 60

Durham Group 54 47

Lune Balder Group 82 75

Cow Green 49 48

Author: GWHCL

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Rainfall

Total rainfall (as a percentage of the long term average) for hydrological areas across North East England for the current month, the last three months, the last six months, and the last 12 months, classed relative to an analysis of respective historic totals. NCIC (National Climate Information Centre) data based on the Met Office 5km gridded rainfall dataset derived from rain gauges (Source: Met Office © Crown Copyright 2018). Provisional data based on Environment Agency 1km gridded rainfall dataset derived from Environment Agency intensity rain gauges.

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www.gov.uk/environment-agency © Environment Agency 2018 4

Above average rainfall Below average rainfall

0%

50%

100%

150%

200%

250%

300%

Oct-17 Jan-18 Apr-18 Jul-18

1-Month Period for Tweed

0%

50%

100%

150%

200%

250%

1-Month Period for Northumbria North Sea Tribs

0%

50%

100%

150%

200%

250%

1-Month Period for Tyne

0%

50%

100%

150%

200%

250%

1-Month Period for Wear

0%

50%

100%

150%

200%

250%

1-Month Period for Seaham, Peterlee Coastal Area

0%

50%

100%

150%

200%

250%

1-Month Period for Tees

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Soil Moisture Deficit

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River Flow

Some features of this map are based on digital spatial data licensed from the Centre for Ecology and Hydrology, © CEH.

Includes material based on Ordnance Survey 1:50 000 maps with the permission of the controller of Her Majesty’s Stationery Office © Crown copyright. All rights reserved. Environment Agency, 100026380, 2018.

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Exceptionally high Notably high Above normal Normal

Below normal Notably low Exceptionally low ─── Latest data

0 2 4 6 8 10 12

30-Nov-17 31-Jan-18 31-Mar-18 31-May-18 31-Jul-18 30-Sep-18 30-Nov-18

Daily Mean Flow (cumecs)

HARTFORD BRIDGE, BLYTH (NE) Ranking used data from 05/03/1963 to 31/12/2012

Sept mean flow 0.245cumecs 24% LTA

0 10 20 30 40 50 60 70 80 90 100

HAYDON BRIDGE, SOUTH TYNE Ranking used data from 07/10/1974 to 31/12/2012

0 5 10 15 20 25 30 35 40 45 50

HEATON MILL, TILL (NE) Ranking used data from 25/04/2002 to 31/12/2012

0 5 10 15 20 25 30 35 40 45 50

MIDDLETON IN TEESDALE, TEES Ranking used data from 01/05/1971 to 31/12/2012

0 2 4 6 8 10 12 14 16 18 20

MITFORD, WANSBECK Ranking used data from 01/11/1968 to 31/12/2012

0 5 10 15 20 25 30

ROTHBURY, COQUET Ranking used data from 01/06/1972 to 31/12/2012

0 5 10 15 20 25 30

01-Mar-17 01-May-17 01-Jul-17 01-Sep-17 01-Nov-17 01-Jan-18 01-Mar-18

STANHOPE, WEAR Ranking used data from 01/10/1958 to 31/12/2012

No data available from 21st May 2017

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Groundwater Levels

Some features of this map are based on digital spatial data licensed from the Centre for Ecology and Hydrology, © CEH.

Includes material based on Ordnance Survey 1:50 000 maps with the permission of the controller of Her Majesty’s Stationery Office © Crown copyright. All rights reserved. Environment Agency, 100026380, 2018.

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Exceptionally high Notably high Above normal Normal

Below normal Notably low Exceptionally low ─── Latest data

42.0 42.5 43.0 43.5 44.0 44.5 45.0 45.5 46.0

Dec-17 Feb-18 Apr-18 Jun-18 Aug-18 Oct-18

Level (mAOD)

ROYALTY OBSERV.

Ranking derived from data for the period Dec-1990 to Dec-2012

3.0 3.5 4.0 4.5 5.0 5.5 6.0

Level (mAOD)

RED LION

Ranking derived from data for the period Aug-1993 to Dec-2012

75 77 79 81 83 85

Level (mAOD)

AYCLIFFE NRA2

Ranking derived from data for the period Mar-1979 to Dec-2012

137.0 137.5 138.0 138.5 139.0 139.5 140.0

Level (mAOD)

TOWNLAW

Ranking derived from data for the period Aug-2001 to Nov-2012

1.0 1.4 1.8 2.2 2.6 3.0

Level (mAOD)

WEST HALL FARM

Ranking derived from data for the period Mar-1979 to Dec-2012

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Reservoir Stocks - data from Water Company

0 10 20 30 40 50 60 70 80 90 100

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

Percentage of live capacity

Kielder

2018 Min Max Mean

0 10 20 30 40 50 60 70 80 90 100

Percentage of live capacity

N Tyne Group

2017 Min Max Mean

0 10 20 30 40 50 60 70 80 90 100

Derwent

2018 Min Max Mean

0 10 20 30 40 50 60 70 80 90 100

Durham

2018 Min Max Mean

0 10 20 30 40 50 60 70 80 90 100

Cow Green

2018 Min Max Mean

0 10 20 30 40 50 60 70 80 90 100

Lune Balder

2018 Min Max Mean

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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).

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

Groundwater The water found in an aquifer

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

Reservoir live capacity The reservoir capacity normally usable for storage to meet established reservoir operating requirements. It is the total capacity less that not available because of operating agreements or physical restrictions. Only under abnormal conditions, such as a severe water shortage might this additional water be extracted.

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

Expressed in depth of water (mm).

Exceptionally high Value likely to fall within this band 5% of the time Notably high Value likely to fall within this band 8% of the time Above normal Value likely to fall within this band 15% of the time Normal Value likely to fall within this band 44% of the time Below normal Value likely to fall within this band 15% of the time Notably low Value likely to fall within this band 8% of the time Exceptionally low Value likely to fall within this band 5% of the time

Monthly water situation report