THE IMPACT OF URBAN GROUNDWATER UPON SURFACE WATER QUALITY: BIRMINGHAM – RIVER TAME STUDY, UK. by PAUL AUSTIN ELLIS A thesis submitted to The University of Birmingham for the degree of DOCTOR OF PHILOSOPHY Hydrogeology Group School of Geography, Earth and Environmental Sciences The University of Birmingham December 2002 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. ABSTRACT A field-based research study has been undertaken on the River Tame within the industrial city of Birmingham, UK, to understand better the influence of urban groundwater discharge on surface-water quality. The 8 km study reach receives ~6% of its total baseflow (60% of which is groundwater) from the underlying Triassic Sandstone aquifer and flood-plain sediments. An integrated set of surface water and groundwater flow, head and physical/chemical data was collected from installed riverbed piezometers and existing monitoring across the aquifer. Field data and supporting computer modelling indicated the convergence of groundwater flows from the sandstone/drift deposits and variable discharge to the river (0.06 to 10.7 m3d-1m-1, mean 3.6 m3d-1m-1), much of which occurred through the riverbanks. Significant heterogeneity was also observed in groundwater quality along and across the river channel. Key contaminants detected were copper, nickel, sulphate, nitrate, chlorinated solvents, e.g. trichloroethene, and their biodegradation products. Groundwater contaminant concentrations were generally lower than expected and ascribed to dilution and natural attenuation within the aquifer and riverbed. High concentration plumes were detected, but their effect was localised due to substantial dilution within the overlying water column of the river. Estimated contaminant fluxes were not found to reduce significantly the present surface water quality, which is poor (>30% is pipe-end discharge). Comparative studies elsewhere and further elucidation of heterogeneity and natural attenuation controls are recommended. To my wife Yumi and sons Max Leo and Ben ACKNOWLEDGEMENTS I would like to thank my supervisors Dr Mike Rivett and Professor Rae Mackay for their advice and enthusiasm during the project. Also my thanks to Dr Rob Ward and Dr Bob Harris at the Environment Agency for the assistance and support they have given during my research. The Environment Agency National Groundwater and Contaminated Land Centre and the School of Earth Sciences, Birmingham University jointly provided the funding for the work. Thanks to Professor Geoff Williams and Julian Trick at the British Geological Survey for the loan of equipment and discussions on piezometer design. For their hard toil in the field, splashing about with the rats in the glorious River Tame, thanks go to James Dowell, John Henstock, Tom Singleton, Amelia Moylett, Chris Fuller, Steve Littler, and Kevin Shepherd. For general advice and assistance I am grateful to Dr Richard Greswell, Roger Livsey, Jane Harris, Mick Riley and Professor John Tellam. Thanks to Nassir Al Amri and Phil Blum for fruitful discussions and being good office mates. To my mother and father thanks for your support over the years and for actually reading the thesis. TABLE OF CONTENTS CHAPTER 1. INTRODUCTION............................................................................................................ 1 1.1 Project outline...............................................................................................................................................1 1.2 Aim and objectives .......................................................................................................................................2 1.3 Approach and thesis layout...........................................................................................................................3 CHAPTER 2. A REVIEW OF GROUNDWATER/SURFACE WATER INTERACTIONS................ 6 2.1 Introduction ..................................................................................................................................................6 2.1.1 Groundwater flow to rivers...................................................................................................................6 2.1.2 The groundwater/surface water interface..............................................................................................9 2.1.3 Groundwater contamination................................................................................................................11 2.2 International Case Studies ..........................................................................................................................16 2.2.1 Water Quality Studies .........................................................................................................................17 2.2.2 Flow Studies........................................................................................................................................18 2.2.3 Combined Quality and Flow Studies ..................................................................................................19 2.3 UK Case Studies.........................................................................................................................................20 2.3.1 UK Legislation....................................................................................................................................22 2.4 Monitoring methods....................................................................................................................................22 2.5 Modelling methods .....................................................................................................................................23 2.6 Conclusions ................................................................................................................................................25 CHAPTER 3 STUDY SETTING.......................................................................................................... 26 3.1 Historical Background................................................................................................................................26 3.2 Land use......................................................................................................................................................29 3.3 Hydrology of the River Tame.....................................................................................................................30 3.4 The Geology of the Tame Catchment.........................................................................................................34 3.4.1 Solid Geology .....................................................................................................................................38 3.4.2 Superficial Drift Deposits ...................................................................................................................39 3.4.3 Structure..............................................................................................................................................41 3.5 Regional Hydrogeology..............................................................................................................................41 3.6 Hydrochemistry and Contamination of the Birmingham Aquifer ..............................................................47 3.6.1 Inorganic Contamination.....................................................................................................................52 3.6.2 Organic Contamination.......................................................................................................................54 3.7 Summary.....................................................................................................................................................55 CHAPTER 4 MONITORING NETWORKS AND METHODS .......................................................... 57 4.1 Overview ....................................................................................................................................................58 4.2 Archive data................................................................................................................................................65 4.3 Surface water flow gauging. .......................................................................................................................67 4.3.1 River discharge measurements............................................................................................................67 4.3.2 River cross sectional discharge calculation.........................................................................................69 4.4 Surface water quality sampling...................................................................................................................70 4.5 Groundwater quality sampling....................................................................................................................70 4.5.1 Riverbed