Fylde Aquifer/Wyre Catchment Water Resources Study Final Report
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FYLDE AQUIFER/WYRE CATCHMENT WATER RESOURCES STUDY ———-■ OVMMflNr,n Final Report August 1997 Environment • A g s n c y n n MacDonald < • ' FYLDE AQUIFER RECATCHMENT WATER RESOURCES STUDY •• carried out for the Environment, Agency (North W est Region), in conjunction with.-Nortii West W ater Ltd, by Mott MacDonald ■ :- August 1997 ^ En v ir o n m e n t A g e nc y B m r ft Mott N o r t K f £ L I! ■» ' ■i i En vir o n m ent II Agency li 3' i f t ‘ •-* ») FYLDE AQl £FER/ W Y * ^ " CATCHMENT J i WATER RESOURCES i ;!■ STUDY I \i ' t H r | “l : | ■ j I ’l FINAL REPORT ? Mi jif r tC. ; AUGUST 1997 *■4 ft Mott I i m MacDonald II Env iro n m ent Agency NATIONAL LIBRARY & INFORMATION SERVICE HEAD OFFICE Rio House. Waterside Drive, Aztec West, Almondsbury, Bristol BS32 4UD Q k - TABLE OF CONTENTS 38436ba01/2/C Acknowledgements The Authors and Project Board would like to thank the following for their valuable assistance during the course of the Study and the preparation of this report: • Environment Agency - Area Water Resources staff Regional Groundwater and Hydrology colleagues • ProfK RRushton • North West Water Ltd • Rod Ireland • • British Geological Survey • AQuatic Pollution & Management Ltd. (APEM) • . British Nuclear Fuels ICI • Whitbread and all other companies, organisations and individuals who provided data, access to records or otherwise contributed to the Study / FYLDE AQUIFER/WYRE CATCHMENT WATER RESOURCES STUDY FINAL REPORT TABLE OF CONTENTS Page Nr EXECUTIVE SUMMARY S-l CHAPTER 1 INTRODUCTION 1.1 Extent of the Study Area 1-1 1.2 Background Need 1-1 1.3 Aims and Objectives 1-2 1.4- Catchment Description 1-3 1.5 Development of Water Supplies 1-3 1.6 Previous Studies 1-5 1.7 Study Structure 1-9 1.8 Organisations Contributing Data 1-1 1 End Page 1-12 CHAPTER 2 HYDROLOGY AND HYDROGEOLOGY 2.1 Hydrology and Land Use 2-1 2.1.1 Rainfall 2-1 2.1.2 Evapotranspiration 2-1 2.1.3 River Flows 2-3 2.1.4 Surface Water Transfers and Abstractions 2-4 2.1.5 Hydrological Modelling 2-5 2.1.6 River Geometry . 2-6 2.1.7 LandUse 2-6 2.2 Geology * 2-7 2.2.1 Geological Setting 2-7 2.2.2 Solid Geology 2-8 2.2.2.1 Lithostratigraphy • 2-8 2.2.2.2 Structure 2-9 2.2.3 Drift 2-12 2.3 The Aquifer System 2-14 2.3.1 Carboniferous 2-14 2.3.2 Sherwood Sandstone 2-15 2.3.3 The Drift 2-16 38436BA01/2/C Final Repon TOC >4 Aug 1997 I TABLE OF CONTENTS Page Nr 2.3.4 Mercia Mudstone 2-17 2.4 Groundwater 2-17 2.4.1 Groundwater Abstraction 2-17 2.4.2 Piezometry 2-17 2.4.3 Hydrochemistry 2-19 End Page 2-20 CHAPTER 3 MODEL CONCEPTS, DEVELOPMENT 3.1 General 3-1 3.2 Model Domain and Grid 3-2 3.3 Model Boundary Conditions 3-3 3.3.1 The Carboniferous Boundary 3-3 3.3.2 Morecambe Bay and the Ribble Estuary 3-4 3.3.3 Western and Southern Boundaries 3-4 3.4 Model Layers and Geometry 3-5 3.5 Hydrogeological Characteristics 3-7 3.5.1 Undifferentiated Drift 3-7 3.5.2 Sand & Gravels Directly Overlying Sandstone 3-10 3.5.3 Sandstone 3-10 3.5.4 Carboniferous Deposits and Contact Between Carboniferous and Sandstone 3-11 3.6 Simulation of River/AQuifer Interaction 3-12 3.6.1 Leakage Between Rivers and AQuifers 3-12 3.6.2 Surface River Flows 3-15 3.7 Simulation of Recharge 3-15 3.7.1 Definition of Terms 3-15 3.7.2 Potential Recharge 3-17 3.7.3 Actual Recharge to the Drift Water Table 3-18 3.7.4 Recharge Through the Drift to the Underlying AQuifer 3-18 3.8 Abstractions, Augmentation and Transfers 3-19 3.9 Model Calibration: Criteria and Processes , 3-20 3.9.1 Calibration Criteria 3-20 3.9.2 Calibration Processes 3-21 End Page 3-21 38436BA01/2/C Final Report TOC 14 Aug 1997 ii TABLE OF CONTENTS Page Nr CHAPTER 4 MODEL RESULTS 4.1 Introduction 4-1 4.2 Area I: North West Fylde 4-3 4.2.1 Features of the Area 4-3 4.2.2 Hydrology of the Area 4-3 4.2.3 Geology 4-3 4.2.4 Hydrogeological Data and Simulated AQuifer Properties 4-4 4.2.5 Results of Model Simulations 4-6 4.3 Area 2: Garstang 4-9 4.3.1 Features of the Area - 4-9 4.3.2 Hydrology of the Area 4-9 4.3.3 Geology 4-10 4.3.4 Hydrogeological Data and Simulated Aquifer Properties 4-11 4.3.5 Results of Model Simulations 4-13 4.4 Area 3: Central Fylde 4-17 4.4.1 Features of the Area 4-17 4.4.2 Hydrology of the Area 4-17 4.4.3 Geology 4-18 4.4.4 Hydrogeological Data and Simulated AQuifer Properties 4-19 4.4.5 Results of Model Simulations 4-22 4.5 Area 4: Preston & Southern Fylde 4-26 4.5.1 Features of the Area # 4-26 4.5.2 Hydrology of the Area 4-26 4.5.3 Geology 4-27 4.5.4 Hydrogeological Data and Simulated AQuifer Properties 4-29 4.5.5 Results of Model Simulations 4-34 4.6 Area 5: South East Fylde 4-37 4.6.1 Features of the Area 4-37 4.6.2 Hydrology in the Area 4-37 4.6.3 Geology 4-37 4.6.4 Hydrogeological Data and Simulated AQuifer Properties 4-38 4.6.5 Results of Model Simulations 4-40 4.7 Regional Model 4-41 4.7.1 Simulated Water Balance Components 4-41 4.7.2 Modelled Parameters 4-46 /• 38436BA01/2/C Final Report TOC 14 Aug 1997 iii TABLE OF CONTENTS Page Nr 4.8 Model Sensitivity 4-49 4.8.1 Introduction 4-49 4.8.2 Horizontal Permeability of the Sandstone AQuifer 4-51 4.8.3 Permeability of the Carboniferous Deposits 4-51 4.8.4 Vertical Permeability Between Upper and Lower Sandstone Layers 4-51 4.8.5 Drift Vertical Permeability 4-52 4.8.6 Sands & Gravels 4-52 4.8.7 River Resistance 4-52 4.8.8 Drift Specific Yield 4-53 4.8.9 Summary of Sensitivity Analysis 4-53 4.9 Conclusions From Model Calibration 4-55 End Page 4-56 CHAPTER 5 MODEL PREDICTIONS 5.1 Introduction 5-1 5.2 Comparison of Predictions Based on Different Model Calibrations 5-8 5.3 Minimum and Nominal Maximum NWW Abstractions 5-11 5.4 Influence of Present NWW Abstraction Licences on Groundwater Levels and River Flows 5-12 5.5 Impact of Present Fylde Licences 5-16 5.6 Licensed Augmentations 5-18 5.7 Licence Applications in the Preston Area 5-21 End Page 5-22 CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS 6.1 Conclusions 6-1 • 6.1.1 Specific Objectives 6-1 6.1.2 Overall Aims 6-7 6.2 Recommendations 6-8 6.2.1 Hydrological Research 6-8 6.2.2 Observation Borehole Network Enhancement 6-9 6.2.3 Monitoring 6-9 6.2.4 Model Updates 6-11 6.2.5 Management Plan 6-11 End Page 6-12 38436BA01/2/C Final Repon TOC 14 Aug 1997 iv BIBLIOGRAPHY APPENDICES Appendix A Original Terms of Reference for the Study Appendix B Groundwater Licences of the Fylde Aquifer Appendix C Simulated Water Balance Components for the Model Calibration Appendix D Influence of New Licence in Preston ( Emmetl Denim Care Ltd) Appendix E Drift Leakage Investigation Appendix F Mott MacDonald Quality Assurance Report Distribution Sheet 38436BA0J/2/C Final Report TOC 14 Aug 1997 V List of Tables Page Nr 1.1 LCUS - Fylde AQuifer Licence Conditions 1-7 1.2 Summary of Data Collected 1-11 2.1 Summary of Rainfall Records Used for Preliminary Hydrological Modelling 2-2 2.2 Annual Potential Evapotranspiration (PE) 2-2 2.3 Gauging Station Records 2-3 2.4 Summary of Geological Succession 2-8 '3.1 Geometry of Fylde AQuifer System 3-6 3.2 Initial Drift Hydrogeological Parameters 3-9 3.3 Drift Hydrogeological Parameters at Final Calibration of the Model 3-9 4.1 Observation Boreholes - North West Fylde 4-5 4.2 North West Fylde - Simulated and Observed Groundwater Levels 4-7 4.3 Observation Boreholes - Garstang Area 4-12 4.4 Garstang-Simulated and Observed Groundwater Levels 4-15 4.5 Observation Boreholes - Central Area 4-20 4.6 Central Fylde - Simulated and Observed Groundwater Levels 4-24 4.7 Observation Boreholes - Preston & Southern Fylde 4-31 4.8 Preston & Southern Fylde - Simulated and Observed Groundwater Levels 4-36 4.9 Observation Boreholes - South East Fylde 4-39 4.10 South East Fylde - Simulated and Observed Groundwater Levels 4-41 4.11 Average Simulated Water Balance Components 1972 - 1995 4-43 4.12 Simulated Water Balance Components for September 1995 4-44 4.13 Simulated Water Balance Components for April 1987 4-45 4.14 Sensitivity of Model Parameters 4-50 4.15 Range in AQuifer and River Properties Resulting in Relatively Accurate Simulations 4-54 5.1 Model Predictions 5-2 5.2 Average Simulated Water Balance Components (Years 3 - 26) Comparing Results of Simulation with NWW Sources at Full Licences 5-10 5.3 Average Simulated Water Balance Components (Years 3 - 27) Comparing Results of Simulation Runs 2 and 8 5-14 5.4 Simulated Water Balance Components For Peak.Abstraction Year (27) Comparing Results of Simulation Runs 2 and 8 5-15 5.5 Maximum Simulated Leakage from the River System (Year 27) * 5-17 3&436BA0I/2/C Final Report TOC 14 Aug 1997 vi 4 List of Tables Page Nr 5.6 Average Simulated Water Balance Components (Years 3 - 27) z Comparing Results of Simulations 2 and 9 (Full Licence Conditions) 5-19 5.7 Simulated Water Balance Components For Peak Abstraction Year (27) Comparing Results of Simulations 2 and 9 (Full Licence Conditions) 5-20 3&436BA01/2/C Final Report TOC 14 Aug 1997 vii LIST OF FIGURES 1.1 Location Map 1.2 Lancashire Conjunctive Use Scheme 2.1 Rainfall and River Gauging Stations 2.2A Regional Geological Map (based on Published BGS Maps) 2.2B Revised Regional Geological Map 2.3 Cross Section Showing Deep Structure 2.4 Cross Section Showing Drift Geology 2.5 Base of Sherwood Sandstone 2.6 Structure of Carboniferous/Permo-Triassic Contact 2.7 Top of Sherwood Sandstone 2.8 Thickness of Drift 2.9 Thickness of Boulder Clay 2.10 Mean Section Permeability of Sandstone AQuifer 2.11 Location of Abstraction Boreholes 2.12 Historical Annual Groundwater Abstractions 2.13 Location of Observation Boreholes 2.14 Piezometry April 1987 and September 1976 2.