Appendix 1 Water Resource Zone Characteristics Contents
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draft Drought Plan 2022 Appendix 1 Water Resource Zone characteristics Contents Water Resource Zone characteristics 3 Area 1: Lincolnshire and Nottinghamshire 5 Central Lincolnshire 5 Bourne 7 East Lincolnshire 8 Nottinghamshire 10 South Lincolnshire 11 Area 2: Ruthamford 12 Ruthamford Central 12 Ruthamford North 13 Ruthamford South 15 Ruthamford West 17 Area 3: Fenland 18 North Fenland 18 South Fenland 19 Area 4: Norfolk 20 Happisburgh 20 North Norfolk Coast 21 North Norfolk Rural 23 Norwich and The Broads 25 South Norfolk Rural 27 Area 5: East Suffolk and Essex 28 Central Essex 28 East Suffolk 29 South Essex 31 Area 6: Cambridgeshire and West Suffolk 33 Cheveley, Ely, Newmarket, Sudbury, Ixworth, and Bury-Haverhill 33 Thetford 36 Area 7: Hartlepool 37 Hartlepool 37 2 Water Resource Zone characteristics The uneven nature of climate, drought, growth and List of WRMP 2019 WRZs, in order of discussion: environmental impacts across our region means we have developed Water Resource Zones (WRZs). WRZs Area 1: Lincolnshire and Nottinghamshire are the geographical areas used to develop forecasts Central Lincolnshire of supply, demand and supply-demand balances. The WRZ describes an area within which supply Bourne infrastructure and demand centres are linked such East Lincolnshire that customers in the WRZ experience the same risk Nottinghamshire of supply failure. These were reviewed in the Water Resources Management Plan (WRMP) 2019. South Lincolnshire Area 2: Ruthamford Overall, we increased the number of WRZs from 19 in the WRMP 2015 to 28 for the WRMP 2019, including Ruthamford Central the addition of South Humber Bank which is a non- Ruthamford North potable WRZ that sits within Central Lincolnshire. Ruthamford South The revised list of WRZs are listed below and Ruthamford West shown in Figure 1. For each WRZ we describe the characteristics of the zone, details of previous Area 3: Fenland droughts experienced and current drought risk. North Fenland Through WRMP 2019 modelling, we have assessed our South Fenland drought risk for each WRZ and consider the majority to be secure up to a 1 in 200 year event. There are Area 4: Norfolk five zones where we have identified remaining Happisburgh vulnerabilities and we have proposed supply-side investment schemes in the WRMP. North Norfolk Coast North Norfolk Rural These will be completed by the end of AMP7. Should Norwich and The Broads a severe drought occur before this time, we have identified ‘interim options’, inAppendix 3. Demand South Norfolk Rural drought measures we would undertake for each WRZ to ensure security of supply are detailed in Appendix Area 5: East Suffolk and Essex 2. Section 3.4 and Appendix 12 also include high Central Essex level actions should an extreme drought (1 in 500 East Suffolk year event) occur, although given the unlikely and uncertain nature of such an event these actions have South Essex not been detailed at a WRZ level. Area 6: Cambridgeshire and West Suffolk Bury-Haverhill Cheveley Ely Ixworth Newmarket Sudbury Thetford Area 7: Hartlepool Hartlepool 3 Figure 1: WRZs from the WRMP 2019 4 Area 1: Lincolnshire and Nottinghamshire Central Lincolnshire Characteristics The Central Lincolnshire WRZ covers an area of 2072km2 and extends south from the Humber. It includes groundwater abstraction from the Lincolnshire Limestone and a surface water abstraction from the River Trent. It is based on the supply systems for Scunthorpe and Lincoln. Hall WTW was opened in July 2014, and treats water abstracted from the River Trent for supply to customers in Lincoln. Source details Approximate % groundwater / Water Treatment Source surface water WRZ split WRZ Water source Works type % groundwater % surface water Branston Booths GW Confined Lincs Limestone Dunston GW Confined Lincs Limestone Hall SW River Trent Newton GW Sherwood Sandstone Central Waddingham GW Confined Lincs Limestone 83 17 Lincs Welton GW Confined Lincs Limestone Barrow GW Lincs Chalk River Ancholme / Elsham (Potable) GW / SW Lincs Chalk Winterton GW Confined Lincs Limestone 5 Drought risk Drought risk has been assessed for up to a 1 in 200 year drought event as part of our WRMP 2019. This identified the Hall surface water intake on the River Trent as being vulnerable to a drought of this severity. There are three classified drought vulnerable groundwater sources (Tier 1): Goxhill, Welton and Winterton Holmes. We have also reviewed our risk to a 1 in 500 year extreme drought. This identified additional vulnerability is likely to be seen at the River Trent intake, and the groundwater sources of; Barrow, Barton, Ulceby, Branston Booths, Glentham, Hibaldstow Bridge, Redbourne, Spridlington, Waddingham. Drought Plan management actions There is an interim option proposed for Central Lincs to mitigate modelled vulnerability to a severe drought in this zone. This option is a drought permit on the River Trent at our Hall WTW intake to lower the minimum residual flow to allow increased abstraction in times of low flows. To ensure security of supply is maintained at the drought vulnerable groundwater sources, we can increase abstraction from less vulnerable sources within the zone and transfer supply from sources in the East Lincolnshire zone. We have also invested in a new borehole at Winterton to maintain supply. Cadney direct intake is reliant on augmentation of the flow of the River Ancholme by the Environment Agency’s Trent-Witham-Ancholme (TWA) transfer scheme during lower summer flows. The TWA scheme is managed by the Environment Agency under a Section 20 agreement. Analysis shows this intake is secure against the worst historic and modelled 1 in 200 year droughts1. 1 Atkins (2017) Trent Witham Ancholme Assessment Memo 6 Bourne Characteristics The Bourne WRZ covers an area of 1087km2 and lies to the south west of the Wash. It is based on the supply systems for Bourne, Spalding and Stamford. Water is abstracted from groundwater sources in the Southern Lincolnshire Limestone aquifer. Source details Approximate % groundwater / Water Treatment Source surface water WRZ split WRZ Water source Works type % groundwater % surface water Bourne GW Confined Lincs Limestone Etton GW Confined Lincs Limestone Bourne Pilsgate GW Confined Lincs Limestone 100 0 Tallington GW Confined Lincs Limestone Wilsthorpe GW Confined Lincs Limestone The need for river support in the lower reaches identified this zone as not being vulnerable to a of the River Glen was addressed through the drought of this severity. commissioning of the Gwash-Glen transfer scheme in 1991. The scheme is operated by the Environment We have also reviewed our risk to a 1 in 500 year Agency through a Section 20 Agreement with extreme drought. This identified additional Anglian Water by which water is released from vulnerability is likely to be seen at; Bourne, Pilsgate, Rutland Water on request. This secures an increased Tallington, and Wilsthorpe. level of abstraction from the southern Lincolnshire Limestone aquifer. Drought Plan management actions Drought risk There are no specific drought measures other than demand management actions. Drought risk has been assessed for up to a 1 in 200 year drought event as part of our WRMP 2019. This 7 East Lincolnshire Characteristics The East Lincolnshire WRZ covers an area of 2783km2, extending from the Humber to the Wash and is based on the supply systems for Grimsby, Louth, Skegness, and Boston. The supplies are primarily groundwater abstractions from the Lincolnshire Chalk, Lincolnshire Limestone and Spilsby Sandstone. There is also surface water abstraction from the Louth Canal into Covenham pumped storage reservoir. Source details Approximate % groundwater / Water Treatment Source surface water WRZ split WRZ Water source Works type % groundwater % surface water Confined Spilsby Candlesby GW Sandstone Confined Spilsby Driby GW Sandstone Fordington GW Spilsby Sandstone Fulstow GW Lincs Chalk Lincs Chalk / Spilsby Maltby le Marsh GW Sandstone East 67 33 Lincs Manby GW Spilsby Sandstone Lincs Chalk / Spilsby Mumby GW Sandstone Raithby GW Spilsby Sandstone West Pinchbeck GW Confined Lincs Limestone Barnoldby GW Lincs Chalk Covenham GW Louth Canal 8 Approximate % groundwater / Water Treatment Source surface water WRZ split WRZ Water source Works type % groundwater % surface water Habrough GW Lincs Chalk Healing GW Lincs Chalk Little Coates GW Lincs Chalk East 67 33 Lincs Little London GW Lincs Chalk Tetney GW Lincs Chalk Weelsby GW Lincs Chalk A Section 20 Water Resource Management Drought risk Agreement with the Environment Agency serves to protect and limit the use of the Northern Lincolnshire Drought risk has been assessed for up to a 1 in 200 Chalk aquifer during periods of naturally low year drought event as part of our WRMP 2019. This groundwater levels, which can result in low spring identified this zone as not being vulnerable to a flows from the Lincolnshire Wolds and saline intrusion drought of this severity. along the south bank of the Humber Estuary. We have also reviewed our risk to a 1 in 500 year We abstract from the Louth Canal to fill Covenham extreme drought. This identified there is no reservoir. We also have the option to operate the additional vulnerability. Great Eau transfer scheme to provide a significant increase to the contributory catchment and augment Drought Plan management actions the yield of Covenham reservoir during drought periods. The Great Eau scheme is managed with the The Section 20 management agreement for transfers Environment Agency under a Section 20 agreement. from Great Eau into the Louth Canal, can be utilised on agreement with the Environment Agency. There are two river support schemes in the WRZ, where we provide support from our groundwater sources; one on the Laceby Beck and one on the River Freshney. These are in place during periods of low flow. 9 Nottinghamshire Characteristics The Nottinghamshire WRZ covers an area of 672km2 and lies to the west of the River Trent. The zone is based on the supply systems for Gainsborough and Retford.