Monthly water situation report Devon and Cornwall Area Summary – November 2018 An average of 200 mm of rainfall fell across Devon and Cornwall in November, which is 160% of the long term average (LTA). There were several heavy rainfall events across the month. Monthly mean river flows ranged from ‘normal’ to ‘above normal’ across Devon and Cornwall. Groundwater levels continued to recede with the exception of Bussels No7A, and SMD dropped to 3 mm. Overall, reservoir storage increased from to 50% to 58%. Rainfall An average of 200 mm of rainfall fell across Devon and Cornwall in November, which is 160% of the LTA for the month and is ‘above normal’ for the time of year. There were several rainfall events, the heaviest being around 6 – 9 November, and the end of the month. Rainfall ranged between 215% LTA (Otter, Sid, Axe and Lim), and 105% LTA (Taw and North Devon Streams). Rainfall maps and graph Soil Moisture Deficit The soil moisture deficit had an overall drop over the month. At month end it was at 3 mm which is now equal to the LTA for the time of year. SMD graph and map River Flows Monthly mean river flows ranged from ‘normal’ to ‘above normal’ across Devon and Cornwall. Five rivers had ‘above normal’ flows and 9 had ‘normal’ flows.’ Rivers showed marked changes with the rainfall this month, with many reaching ‘exceptionally high’ flows around 9 November, and nearly all rivers then reaching ‘below normal’ levels in the third week of November. The end of November saw a rise again to high levels including ‘exceptionally high’ levels. This is due to the rivers in Devon and Cornwall being ‘flashy’ and quickly reactive to rainfall. River flow map and graphs Groundwater Levels Groundwater levels continued to recede in November with the exception of Bussels No7A which is starting to show recovery. All stations are at ‘normal’ levels for the time of year, apart from Woodleys No1 which is ‘below normal’. Groundwater map and graphs Reservoir Storage Overall, total reservoir storage rose from 50% in October to 58% across Devon and Cornwall. Wimbleball storage rose to 45%, Colliford rose to 58% and Roadford rose to 50% total storage. Reservoir graphs Author: Devon, Cornwall and the Isle of Scilly Hydrology Team Contact details: 03708 506506 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 Rainfall Figure 1.1: Total rainfall for hydrological areas across Devon and Cornwall for the current month (up to November), the last three months, the last six months and the last 12 months, classed relative to an analysis of respective historic totals. Final 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. Crown copyright. All rights reserved. Environment Agency, 100026380, 2018. www.gov.uk/environment-agency © Environment Agency 2018 Above 100% LTA rainfall Below 100% LTA rainfall 1-Month Period for South West - Devon & Cornwall NCIC 250% 200% 150% 100% Percentage of LTA Percentage 50% 0% Dec-16 Jan-17 Feb-17 Mar-17 Apr-17 May-17 Jun-17 Jul-17 Aug-17 Sep-17 Oct-17 Nov-17 Dec-17 Jan-18 Feb-18 Mar-18 Apr-18 May-18 Jun-18 Jul-18 Aug-18 Sep-18 Oct-18 Nov-18 Figure 1.2: Monthly rainfall totals as a percentage of the 1961 – 1990 long term average. Final 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. Crown copyright. All rights reserved. Environment Agency, 100026380, 2018. Soil Moisture Deficit Less than historic minimum Greater than historic maximum ..... 1961-1990 long term average ── Latest data ── 2017 0 20 40 60 80 100 Soil moisture deficit (mm) 120 140 160 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 2.1: Latest soil moisture deficit compared to previous year, maximum, minimum and 1961 – 1990 long term average. Weekly MORECS data for real land use (Source: Met Office © Crown Copyright, 2018). www.gov.uk/environment-agency © Environment Agency 2018 Month-end Soil Moisture Deficit (mm) Figure 2.2: Soil moisture deficits for week ending 27 November 2018. MORECS data for real land use (Source: Met Office © Crown Copyright, 2018). Crown copyright. All rights reserved. Environment Agency, 100026380, 2018. www.gov.uk/environment-agency © Environment Agency 2018 River Flow Figure 3.1: Monthly mean river flows at indicator sites for November 2018, expressed as a percentage of the respective long term average and classed relative to an analysis of historic November monthly means (Source: Environment Agency). Crown copyright. All rights reserved. Environment Agency, 100026380, 2018. Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Hayle at St Erth Kenwyn at Truro Ranking derived from data for the period 03/01/1968 to 31/12/2012 Ranking derived from data for the period 31/10/1968 to 31/12/2012 5.0 2.0 November mean flow November mean flow 4.5 0.702 cumecs 1.8 0.484 cumecs 66% LTA 95% LTA 4.0 1.6 3.5 1.4 3.0 1.2 2.5 1.0 2.0 0.8 1.5 0.6 1.0 0.4 Daily Mean Flow (cumecs) Daily Mean Flow (cumecs) 0.5 0.2 0.0 0.0 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 www.gov.uk/environment-agency © Environment Agency 2018 Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Gannel at Gwills Camel at Denby Ranking derived from data for the period 01/12/1969 to 31/12/2012 Ranking derived from data for the period 31/08/1964 to 31/12/2012 4.0 35 November mean November mean flow flow 9.94 cumecs 3.5 0.895 cumecs 30 114% LTA 3.0 25 2.5 20 2.0 15 1.5 10 1.0 Daily Mean Flow (cumecs) Daily Mean Flow (cumecs) 0.5 5 0.0 0 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 Fowey at Restormel Tamar at Gunnislake Ranking derived from data for the period 31/03/1961 to 31/12/2012 Ranking derived from data for the period 25/06/1956 to 31/12/2012 35 160 November mean flow November mean flow 7.82 cumecs 42.8 cumecs 140 30 114% LTA 115% LTA 120 25 100 20 80 15 60 10 40 Daily Mean Flow (cumecs) Daily Mean Flow (cumecs) 5 20 0 0 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 Torridge at Torrington Taw at Umberleigh Ranking derived from data for the period 31/07/1960 to 31/12/2012 Ranking derived from data for the period 30/09/1958 to 31/12/2012 140 140 November mean flow November mean 22.9 cumecs flow 120 84% LTA 120 19.4 cumecs 64% LTA 100 100 80 80 60 60 40 40 Daily Mean Flow (cumecs) 20 Daily Mean Flow (cumecs) 20 0 0 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 East Dart at Bellever Dart at Austins Bridge Ranking derived from data for the period 31/03/1964 to 31/12/2012 Ranking derived from data for the period 30/09/1958 to 31/12/2012 10 November mean flow November mean flow 60 9 2.56 cumecs 24.3 cumecs 143% LTA 63% LTA 8 50 7 6 40 5 30 4 3 20 2 Daily Mean Flow (cumecs) Daily Mean Flow (cumecs) 10 1 0 0 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 www.gov.uk/environment-agency © Environment Agency 2018 Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data Teign at Chudleigh Bridge Exe at Thorverton Ranking derived from data for the period 01/01/1958 to 31/12/2012 Ranking derived from data for the period 30/04/1956 to 31/12/2012 50.0 100 November mean flow November mean 45.0 11.2 cumecs 90 flow 135% LTA 15.5 cumecs 40.0 80 152% LTA 35.0 70 30.0 60 25.0 50 20.0 40 15.0 30 10.0 20 Daily Mean Flow (cumecs) Daily Mean Flow (cumecs) 5.0 10 0.0 0 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 Otter at Dotton Axe at Whitford Ranking derived from data for the period 30/09/1962 to 31/12/2012 Ranking derived from data for the period 05/11/1964 to 31/12/2012 25 40 November mean flow November mean flow 5.86 cumecs 10.4 cumecs 35 139% LTA 140% LTA 20 30 25 15 20 10 15 10 5 Daily Mean Flow (cumecs) Daily Mean Flow (cumecs) 5 0 0 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 30-Jan-18 30-Mar-18 30-May-18 30-Jul-18 30-Sep-18 30-Nov-18 Figure 3.2: Indicator river flow sites for Devon and Cornwall.