Monthly Water Situation Report North West England
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Monthly Water Situation Report North West England Summary – August 2021 Table 1. North West England summary of the current water situation. Parameter Current status Rainfall North West England rainfall was 74% of the August Long Term Average (LTA). Classed as ‘Below normal’ this month. Soil Moisture Deficit (SMD) By the end of August, SMD levels had decreased across the majority of North West England compared to levels at the start of August. River Flows Classed between ‘Below normal’ and ‘Above normal’. Groundwater Levels Classed between ‘Normal’ and ‘Exceptionally high’. Reservoir Storage Total North West England reservoir storage decreased from 68% (start of August) to 66% (end of August). Rainfall Rainfall for North West England as a whole was classed as ‘Below normal’ for August (74% of the LTA). The 1-month August rainfall totals across the hydrological areas, indicated that six out of ten areas observed monthly rainfall totals classed as ‘Below normal’, with monthly totals for the remaining four hydrological areas classed as ‘Normal’ (Figure 2). The highest rainfall in August (in terms of percentage of the LTA) was observed in the Mersey and Irwell (91% of the LTA for August, classed as ‘Normal’), with the lowest rainfall being observed in the Wyre and Lune (64% of the LTA, classed as ‘Below normal’) (Figure 3). The first half of August brought the majority of the monthly rainfall total, with the rainfall during the remaining half of August was largely very dry and settled. The 3-month cumulative rainfall totals, between June and August, indicated ‘Exceptionally low’ rainfall across all hydrological areas within Cumbria. In particular, the Esk (Cumbria) and Derwent were ranked as the 4th driest, 3-month cumulative rainfall period (June to August) in 131 years. Notably, the Esk (Dumfries), Eden and Kent which were also ranked 5th driest, 6th driest and 6th driest respectively, for the same period of analysis. The 6-month cumulative rainfall totals (March to August) also indicated that the Esk (Dumfries) was classed as ‘Exceptionally low’ and the 2nd driest in 131 years. However, for North West England there was ‘Exceptionally high’ rainfall in May, which was 176% of the May long term average. This resulted in ‘Normal’ to ‘Exceptionally high’ river flows, helping to refill the reservoirs. The inclusion of May’s rainfall, which ranged between 156% to 202% of the LTA for May across the hydrological areas (with the exception of the Esk Dumfries) and was classed between ‘Notably high’ and ‘Exceptionally high’ across those areas, resulted in the 4-month cumulative total being classed as between ‘Below normal’ and ‘Above normal’, which is similar to classification of the 6-month cumulative period. Soil Moisture Deficit/Recharge In general, the SMD levels decreased during August across most areas of the North West (Figure 4), with the exception of parts of the Weaver catchment in Greater Manchester, Merseyside and Cheshire (GMC) and the coastal areas around Morecambe Bay. In almost all catchments, SMD remains higher than expected for this time of year. Higher SMDs, between 101-130mm, were observed in the parts of GMC. River Flows Despite the lower monthly rainfall totals in August compared to July, monthly mean flows increased in all catchments in the North West, with only flows in the Weaver catchment decreased from the previous month. This may be attributed to several short-lived intense rainfall events earlier in the month, particularly in the period between the 6th and 9th August, which may have skewed the monthly mean flow. River flows were classed between ‘Below normal’ and ‘Above normal’ in comparison to the LTA for August (Figure 5), with the highest flows (in terms of percentage of the LTA) in both the Mersey and Weaver catchments (114% of LTA, classed as ‘Above normal’) and lowest in the Lune (37% of LTA, classed as ‘Below Normal’) (Figure 6). At the end of August, four gauging stations across the North All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the AllEnvironment data are provisional Agency. Its and officers, may be servants subject orto agentsrevision. accept The viewsno liability expressed for any in lossthis ordocument damage arearising not necessarilyfrom the interpretati those of tonhe or Environmentuse of the information, Agency. Its or officers, reliance servants upon views or agents contained accept herein. no liability © Environmentfor any loss or damageAgency arising 2014 from the interpretation or use of the information, or reliance upon views contained herein. © Environment Agency 2021 West (three of which are in Cumbria and Lancashire) were at or below Q95 flow (a Q95 flow is the flow equalled or exceeded 95% of the time within the period of record and is an indicator of low flows). Groundwater Levels Between the end of July and the end of August, groundwater levels have fallen, however have remained classed between ‘Normal’ and ‘Exceptionally high’ (Figure 7). The only changes to the banding classes since last month have occurred at Bruntwood Hall and Skirwith. For August, Crow Lady Farm was classed as ‘Normal’, Bruntwood Hall classed as ‘Above normal’ and Skirwith classed as ‘Notably high’. Brown Bank Lay-By, Richmond Park and Priors Heyes were all classed as ‘Exceptionally high’. The levels at Priors Heyes remained high compared to historic levels because the aquifer is recovering from the effects of historically high abstractions. Reservoir Storage/Water Resource Zone Stocks Reservoir stocks for North West England decreased from 68% at the end of July, to 66% by the end of August (Figure 10). At the end of August, reservoir stock (in terms of percentage) was highest at Crummock (100%) and lowest at Haweswater (43%). Notably, reservoir stocks in the Lakes Group was 49% at the end of August (Figure 1). The combined storage at Haweswater and Thirlmere was below average for the time of year (46% compared to an average of 71%) and 33% lower than this time last year. Audenshaw No.1 and High Bullough were among the reservoirs kept low for maintenance works. Haweswater Reservoir Level 1 Level 2 Level 3 Enhanced monitoring and operations 100 90 80 70 60 50 40 30 20 Percentage of live Percentage ofcapacity live 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 1: Storage in Haweswater reservoir including the drought levels for the reservoir and storage for representative years; 1995, 2003, 2010, 2018 and 2020. (Source: United Utilities). Contact: Cumbria and Lancashire Hydrology team: [email protected] or Greater Manchester, Merseyside and Cheshire Hydrology team: [email protected] 2 Rainfall Crown Copyright. All rights reserved. Environment Agency, 100024198, 2021 Figure 2. Total rainfall (as a percentage of the LTA) for hydrological areas across North West 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. HadUK data based on the Met Office 1km gridded rainfall dataset derived from rain gauges (Source: Met Office © Crown Copyright 2021). Provisional data based on Environment Agency 1km gridded rainfall dataset derived from Environment Agency intensity rain gauges. Go to the Glossary Return to Summary 3 Above average rainfall Below average rainfall 1-Month Period for North-west England 1-Month Period for Cumbria and Lancashire 300% 300% 250% 250% 200% 200% 150% 150% 100% 100% 50% 50% 0% 0% Nov-20 Nov-20 Sep-20 Oct-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Sep-20 Oct-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 1-Month Period for Greater Manchester, Merseyside and 1-Month Period for Cumbria and Lancashire (Cumbria) Cheshire 300% 300% 250% 250% 200% 200% 150% 150% 100% 100% 50% 50% 0% Sep-20 Dec-20 Nov-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Oct-20 0% Nov-20 Aug-21 Sep-20 Oct-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jun-21 Jul-21 1-Month Period for Cumbria and Lancashire (Lancashire) 1-Month Period for Esk (Cumb) 300% 300% 250% 250% 200% 200% 150% 150% 100% 100% 50% 50% 0% Sep-20 Jun-21 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jul-21 Aug-21 Oct-20 0% Apr-21 May-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Jun-21 Jul-21 Aug-21 1-Month Period for Derwent (NW) 1-Month Period for Eden 300% 300% 250% 250% 200% 200% 150% 150% 100% 100% 50% 50% 0% Dec-20 Mar-21 Oct-20 Nov-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 0% Sep-20 Sep-20 Feb-21 Aug-21 Oct-20 Nov-20 Dec-20 Jan-21 Mar-21 Apr-21 May-21 Jun-21 Jul-21 4 Above average rainfall Below average rainfall 1-Month Period for Esk (Dumfries) 1-Month Period for Cheshire Rivers Group 300% 300% 250% 250% 200% 200% 150% 150% 100% 100% 50% 50% 0% May-21 Jul-21 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 Jun-21 Aug-21 0% Sep-20 Jun-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jul-21 Aug-21 1-Month Period for Kent 1-Month Period for Mersey and Irwell 300% 300% 250% 250% 200% 200% 150% 150% 100% 100% 50% 50% 0% Oct-20 Jun-21 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jul-21 Aug-21 Sep-20 0% Jun-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jul-21 Aug-21 1-Month Period for Douglas 1-Month Period for Ribble 300% 300% 250% 250% 200% 200% 150% 150% 100% 100% 50% 50% 0% 0% Apr-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 May-21 Jun-21 Jul-21 Aug-21 Jan-21 Sep-20 Oct-20 Nov-20 Dec-20 Feb-21 Mar-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 1-Month Period for Wyre and Lune 300% 250% 200% 150% 100% 50% 0% Mar-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Figure 3: Monthly rainfall totals for the past 12 months expressed as a percentage of the long term average (1961-90), for North West England and its hydrological areas using HadUK data based on the Met Office 1km gridded rainfall dataset derived from rain gauges (Source: Met Office © Crown Copyright 2021).