DOCSLIB.ORG

Management of the London Basin Chalk Aquifer

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Management of the London Basin Chalk Aquifer Management of the London Basin Chalk Aquifer Status Report 2009 We are the Environment Agency. It's our job to look after your environment and make it a better place - for you, and for future generations. Your environment is the air you breathe, the water you drink and the ground you walk on. Working with business, Government and society as a whole, we are making your environment cleaner and healthier. The Environment Agency. Out there, making your environment a better place. Environment Agency Rio House Waterside Drive, Aztec West Almondsbury, Bristol BS32 4UD Tel: 0870 8506506 Email: [email protected] www.environment-agency.gov.uk © Environment Agency All rights reserved. This document may be reproduced with prior permission of the Environment Agency. Environment Agency Management of the London Basin Chalk Aquifer Status Report 2009 Contents 1 Introduction .................................................................................................................................. 2 2 Geology beneath London............................................................................................................. 3 3 Groundwater beneath London ..................................................................................................... 5 4 Why we need to manage groundwater levels.............................................................................. 7 5 How we manage groundwater levels........................................................................................... 9 6 Recent Abstraction trends.......................................................................................................... 10 7 Groundwater levels for January 2009........................................................................................ 11 Recent Changes in Groundwater Levels................................................................................... 11 Long Term Changes in Groundwater Levels............................................................................. 11 8 Current licensing strategy .......................................................................................................... 13 9 Recent and developing management issues............................................................................. 15 Open Loop Ground source heat pump (GSHP) systems .......................................................... 15 Thames Tideway Tunnel............................................................................................................ 16 Crossrail..................................................................................................................................... 16 Source Protection Zones ........................................................................................................... 16 10 Conclusions ........................................................................................................................... 18 Figures.............................................................................................................................................. 19 Appendix A London Basin Hydrographs List of abbreviations Environment Agency Management of the London Basin Chalk Aquifer 1 Status Report 2009 1 Introduction Thames Region of the Environment Agency produces an annual report on the state of groundwater levels in the Chalk aquifer beneath London. This is the eighteenth such report (previously called ‘Groundwater Levels in the Chalk-Basal Sands Aquifer of the London Basin’). The reports were started in the 1990s to record the rise in groundwater levels, resulting from a significant reduction in groundwater abstraction from the Chalk aquifer beneath London, which started during the mid-1960s. The rising groundwater and the re-saturation of the Chalk and overlying deposits can potentially affect the stability of buildings and tunnels. However, falling groundwater levels and de-saturation of the Chalk can impact local abstractors ability to abstract groundwater. This report aims to describe the current condition of groundwater levels and abstraction within the Chalk and understand any changes seen in recent years. The area looked at within this report is shown in Figure 1. In order to manage groundwater levels to protect infrastructure and water resources, this monitoring data is used to see if changes to the local licensing policy need to be made to manage groundwater levels further. The current licensing policy is described as well as new and developing issues for groundwater management in the London Basin. Environment Agency Management of the London Basin Chalk Aquifer 2 Status Report 2009 2 Geology beneath London The geology of the London Basin is shown in Figure 2. Table 1 shows the geological formations found within the London Basin, the geological age that they were formed and their typical thickness. Table 1 Geology of the London Basin Era Group Formation Thickness (m) Palaeogene Thames Bagshot Formation 10 – 25 Claygate Member 30-90 London Clay Harwich Formation 0-10 Lambeth Woolwich and Reading Beds 10-20 Upnor Formation 5-7 Thanet Sands 0-30 Cretaceous Chalk 180-245 From the British Geological Survey Memoir Geology of London, 2004 As Table 1 shows, the Cretaceous sediments comprise of Chalk, and are overlain by Tertiary deposits of Thanet Sands, which consists of a fine sand, the Lambeth Group, comprising of sands, silts and clays, and Harwich Formation, comprising of sands and gravels. Overlying the Lambeth Group is London Clay, a dense blue/grey fissured clay. The Bagshot Formation, Bracklesham Formation and Claygate Member overlie the London Clay. Approximately half of the surface geology of the London Basin is formed by these younger deposits. These deposits form the London Basin Syncline, which is asymmetric in shape. The northern limb of the syncline dips shallowly at around 1 degree to the south east, from its high point in the Chilterns. The southern limb in places dips steeply at up to 55 degrees at the Hogsback near Guildford in Surrey, decreasing in an easterly direction to 18 degrees at Gomshall and then to 1 degree at Dorking. The London Clay is up to 80 metres thick at Hammersmith in the west, and Rainham in the east, and confines the Chalk aquifer over most of London. The depth to chalk increases to the southwest of the central basin area, with the greatest depth to Chalk in the basin at Chertsey, encountered at over 160 m below surface. Two major faults are present in the south side of the London Basin. The Wimbledon Fault extends from Chessington through Malden, Wimbledon to Deptford. The downthrown block is the north west side of the fault, and has caused movements of beds as high as the London Clay, which is in contact with the Lambeth Group at East Dulwich. The Greenwich Fault runs parallel to the Wimbledon Fault from Mitcham, through West Norwood, Lewisham, Greenwich to Beckton. The downthrown side is also to the north, bringing the chalk into horizontal contact with the Thanet Sand, which contacts Lambeth Group at Lewisham. The maximum displacement is approximately 30 m. Numerous minor faults cross-cut the syncline and have led to the formation of domes, and cause the depth to chalk to vary significantly across the London Basin. The structures have resulted in high ground such as Hampstead-Highgate, Wimbledon and Blackheath, and has brought the chalk to shallow depth below ground and even to outcrop within the basin in the Lee Valley, Deptford, Lewisham, and around the River Thames from Greenwich to Woolwich. In 2008 the British Geological Survey (BGS) completed a geological study of the London Basin for the Environment Agency. Their key findings regarding the basin structure were: Environment Agency Management of the London Basin Chalk Aquifer 3 Status Report 2009 o In the northern part of the basin structural contours indicate gentle, low amplitude and long wavelength folding. This is in contrast to that observed in the southern part, where folding is more numerous, higher in amplitude and shorter in wavelength. o In the northern part, the Chalk dips to the south east at up to 0.7 degrees and the dip is not observed to steepen against structures. However, in the southern part, the dip is generally between 0.7 and 2 degrees to the north west and the dips steepen against structures up to a maximum of 14 degrees. o No evidence for faulting was found in the borehole logs in the northern part. However, numerous small-scale faults were recognised within the southern part. o In the central basin area new faults orientations are proposed (Figure 2), which are supported by the distribution of Lambeth Group deposits. o the known area of complexity within the Lambeth Group of London coincides with the proposed fault pattern. The faults appear to have had a persistent control on the extent of marine transgression and regression during Lambeth Group time, and presumably throughout the Palaeogene, and may control amount and type of sedimentation. Environment Agency Management of the London Basin Chalk Aquifer 4 Status Report 2009 3 Groundwater beneath London The Chalk aquifer is the major aquifer of the London Basin. The Chalk is confined in the basin by the overlying Tertiary formations, which means recharge largely occurs in the Chalk outcrops of the Chilterns to the north and the North Downs to the south. The outcrop to the north of the London Basin is extensive, extending from the outskirts of London at Uxbridge in the west, in a northeasterly direction to Borehamwood and north
Load more

Recommended publications
  • Geology of London, UK
    Proceedings of the Geologists’ Association 123 (2012) 22–45 Contents lists available at ScienceDirect Proceedings of the Geologists’ Association jo urnal homepage: www.elsevier.com/locate/pgeola Review paper Geology of London, UK a, b,c d e c Katherine R. Royse *, Mike de Freitas , William G. Burgess , John Cosgrove , Richard C. Ghail , f g h i j k Phil Gibbard , Chris King , Ursula Lawrence , Rory N. Mortimore , Hugh Owen , Jackie Skipper a British Geological Survey, Keyworth, Nottingham NG12 5GG, UK b First Steps Ltd, Unit 17 Hurlingham Studios, London SW6 3PA, UK c Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK d Department of Earth Sciences, University College London, WC1E 6BT, UK e Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK f Cambridge Quaternary, Department of Geography, University of Cambridge, CB2 3EN, UK g 16A Park Road, Bridport, Dorset, UK h Crossrail Ltd. 25 Canada Square, Canary Wharf, London E14 5LQ, UK i University of Brighton & ChalkRock Ltd, 32 Prince Edwards Road, Lewes BN7 1BE, UK j Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK k Geotechnical Consulting Group (GCG), 52A Cromwell Road, London SW7 5BE, UK A R T I C L E I N F O A B S T R A C T Article history: The population of London is around 7 million. The infrastructure to support this makes London one of the Received 25 February 2011 most intensively investigated areas of upper crust. However construction work in London continues to Received in revised form 5 July 2011 reveal the presence of unexpected ground conditions.
    [Show full text]
  • An Introduction to the Geology and Fossils of Essex
    An Introduction to the Geology and Fossils of Essex The Foundations of Essex The rocks of Essex that were formed before the Ice Age are described as the 'solid' or 'bedrock' geology. Much of the solid geology is concealed beneath unconsolidated sediments laid down during the Ice Age. These Ice Age sediments (sand, gravel etc.) are called 'superficial' or 'drift' deposits. The Oldest Rocks The geological story of Essex starts with rocks that are between 440 and 360 million years old. Dating from the Silurian and Devonian periods these rocks consist of hard, slaty shales, mudstones and sandstones and are over 300 metres below the surface. These rocks have been encountered in boreholes at many places in Essex and they represent a time in the distant past when the first animals were leaving the sea to colonise the land. Similar rocks can be seen at the surface in the Welsh Borderland. Lying on top of these ancient rocks is the Gault, a marly clay from a muddy sea that dates from the middle of the Cretaceous period. This means that, beneath Essex, there is a gap in the geological record that represents about 250 million years and includes the Triassic, Jurassic and early Cretaceous periods. After deposition of the Gault, sand spread into this sea to form a deposit called the Upper Greensand. At this time sea levels were rising leading to widespread flooding of the continents, these are the conditions under which the next rock was formed - the Chalk. The Chalk Chalk is effectively the starting point of our geological story as it is the oldest rock exposed at the surface in our county.
    [Show full text]
  • Northern Thames Basin Area Profile: Supporting Documents
    National Character 111: Northern Thames Basin Area profile: Supporting documents www.naturalengland.org.uk 1 National Character 111: Northern Thames Basin Area profile: Supporting documents Introduction National Character Areas map As part of Natural England’s responsibilities as set out in the Natural Environment White Paper1, Biodiversity 20202 and the European Landscape Convention3, we are revising profiles for England’s 159 National Character Areas (NCAs). These are areas that share similar landscape characteristics, and which follow natural lines in the landscape rather than administrative boundaries, making them a good decision-making framework for the natural environment. NCA profiles are guidance documents which can help communities to inform their decision-making about the places that they live in and care for. The information they contain will support the planning of conservation initiatives at a landscape scale, inform the delivery of Nature Improvement Areas and encourage broader partnership working through Local Nature Partnerships. The profiles will also help to inform choices about how land is managed and can change. Each profile includes a description of the natural and cultural features that shape our landscapes, how the landscape has changed over time, the current key drivers for ongoing change, and a broad analysis of each area’s characteristics and ecosystem services. Statements of Environmental Opportunity (SEOs) are suggested, which draw on this integrated information. The SEOs offer guidance on the critical issues, which could help to achieve sustainable growth and a more secure environmental future. 1 The Natural Choice: Securing the Value of Nature, Defra NCA profiles are working documents which draw on current evidence and (2011; URL: www.official-documents.gov.uk/document/cm80/8082/8082.pdf) 2 knowledge.
    [Show full text]
  • London Basin Advice
    Insightful London Basin Advice The London Basin aquifer is one of the most densely investigated and data-rich groundwater bodies in the UK. Following consolidation and analysis of the available data and a comprehensive literature review, we developed a detailed conceptual understanding of the key hydrogeological processes, which focused on understanding and quantifying the following key aspects of the hydrogeology of the aquifer: 1 Using the most modern interpretation from the British Geological Survey of geological layering and structure to understand the geometry of the aquifer units and potential influence on groundwater flow – see bgs.ac.uk/research/ engineeringGeology/urbanGeoscience/londonAndThames/faultModelling.html 2 Understanding the hydraulic properties of the layered aquifer. Historical interpretations of the Chalk transmissivity distribution were combined with recent pumping tests and depth of burial information to prepare an initial transmissivity map for the model. 3 Understanding groundwater level distributions to identify low permeability barriers (mainly identified as faults or fold axis) and to map areas where the water table was below the base of aquifer units. 4 Quantifying recharge to the North Downs, which contributes almost a half the inflow to the basin; and modelling flows from the springs at the foot of the dip slope which form the upper reaches of the Rivers Hogsmill, Wandle and Ravensbourne. 5 Quantifying other flows into the confined basin, which contribute to most of the abstraction yield. The key source is the unconfined aquifer of the Chilterns, the data for which we obtained from other Environment Agency groundwater models. 6 Assessing interaction with the River Thames where the aquifer is unconfined in East London.
    [Show full text]
  • Geology of London, UK
    Geology of London, UK Katherine R. Royse1, Mike de Freitas2,3, William G. Burgess4, John Cosgrove5, Richard C. Ghail3, Phil Gibbard6, Chris King7, Ursula Lawrence8, Rory N. Mortimore9, Hugh Owen10, Jackie Skipper 11, 1. British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. [email protected] 2. Imperial College London SW72AZ, UK & First Steps Ltd, Unit 17 Hurlingham Studios, London SW6 3PA, UK. 3. Department of Civil and Environmental Engineering, Imperial College London, London, SW7 2AZ, UK. 4. Department of Geological Sciences, University College London, WC1E 6BT, UK. 5. Department of Earth Science and Engineering, Imperial College London, London, SW7 2AZ, UK. 6. Cambridge Quaternary, Department of Geography, University of Cambridge CB2 3EN, UK. 7. 16A Park Road, Bridport, Dorset 8. Crossrail Ltd. 25 Canada Square, Canary Wharf, London, E14 5LQ, UK. 9. University of Brighton & ChalkRock Ltd, 32 Prince Edwards Road, Lewes, BN7 1BE, UK. 10. Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK. 11. Geotechnical Consulting Group (GCG), 52A Cromwell Road, London SW7 5BE, UK. Abstract The population of London is around 7 million. The infrastructure to support this makes London one of the most intensively investigated areas of upper crust. however construction work in London continues to reveal the presence of unexpected ground conditions. These have been discovered in isolation and often recorded with no further work to explain them. There is a scientific, industrial and commercial need to refine the geological framework for London and its surrounding area. This paper reviews the geological setting of London as it is understood at present, and outlines the issues that current research is attempting to resolve.
    [Show full text]
  • The Stratigraphical Framework for the Palaeogene Successions of the London Basin, UK
    The stratigraphical framework for the Palaeogene successions of the London Basin, UK Open Report OR/12/004 BRITISH GEOLOGICAL SURVEY OPEN REPORT OR/12/004 The National Grid and other Ordnance Survey data are used The stratigraphical framework for with the permission of the Controller of Her Majesty’s Stationery Office. the Palaeogene successions of the Licence No: 100017897/2012. London Basin, UK Key words Stratigraphy; Palaeogene; southern England; London Basin; Montrose Group; Lambeth Group; Thames Group; D T Aldiss Bracklesham Group. Front cover Borehole core from Borehole 404T, Jubilee Line Extension, showing pedogenically altered clays of the Lower Mottled Clay of the Reading Formation and glauconitic sands of the Upnor Formation. The white bands are calcrete, which form hard bands in this part of the Lambeth Group (Section 3.2.2.2 of this report) BGS image P581688 Bibliographical reference ALDISS, D T. 2012. The stratigraphical framework for the Palaeogene successions of the London Basin, UK. British Geological Survey Open Report, OR/12/004. 94pp. Copyright in materials derived from the British Geological Survey’s work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail [email protected]. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract. Maps and diagrams in this book use topography based on Ordnance Survey mapping. © NERC 2012.
    [Show full text]
  • Geology of London, UK
    Proceedings of the Geologists’ Association 123 (2012) 22–45 Contents lists available at ScienceDirect Proceedings of the Geologists’ Association jo urnal homepage: www.elsevier.com/locate/pgeola Review paper Geology of London, UK a, b,c d e c Katherine R. Royse *, Mike de Freitas , William G. Burgess , John Cosgrove , Richard C. Ghail , f g h i j k Phil Gibbard , Chris King , Ursula Lawrence , Rory N. Mortimore , Hugh Owen , Jackie Skipper a British Geological Survey, Keyworth, Nottingham NG12 5GG, UK b First Steps Ltd, Unit 17 Hurlingham Studios, London SW6 3PA, UK c Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK d Department of Earth Sciences, University College London, WC1E 6BT, UK e Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK f Cambridge Quaternary, Department of Geography, University of Cambridge, CB2 3EN, UK g 16A Park Road, Bridport, Dorset, UK h Crossrail Ltd. 25 Canada Square, Canary Wharf, London E14 5LQ, UK i University of Brighton & ChalkRock Ltd, 32 Prince Edwards Road, Lewes BN7 1BE, UK j Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK k Geotechnical Consulting Group (GCG), 52A Cromwell Road, London SW7 5BE, UK A R T I C L E I N F O A B S T R A C T Article history: The population of London is around 7 million. The infrastructure to support this makes London one of the Received 25 February 2011 most intensively investigated areas of upper crust. However construction work in London continues to Received in revised form 5 July 2011 reveal the presence of unexpected ground conditions.
    [Show full text]
  • Quaternary River Diversions in the London Basin and the Eastern English Channel"
    Article "Quaternary River Diversions in the London Basin and the Eastern English Channel" D. R. Bridgland et P. L. Gibbard Géographie physique et Quaternaire, vol. 51, n° 3, 1997, p. 337-346. Pour citer cet article, utiliser l'information suivante : URI: http://id.erudit.org/iderudit/033132ar DOI: 10.7202/033132ar Note : les règles d'écriture des références bibliographiques peuvent varier selon les différents domaines du savoir. Ce document est protégé par la loi sur le droit d'auteur. L'utilisation des services d'Érudit (y compris la reproduction) est assujettie à sa politique d'utilisation que vous pouvez consulter à l'URI https://apropos.erudit.org/fr/usagers/politique-dutilisation/ Érudit est un consortium interuniversitaire sans but lucratif composé de l'Université de Montréal, l'Université Laval et l'Université du Québec à Montréal. Il a pour mission la promotion et la valorisation de la recherche. Érudit offre des services d'édition numérique de documents scientifiques depuis 1998. Pour communiquer avec les responsables d'Érudit : [email protected] Document téléchargé le 12 février 2017 08:33 Géographie physique et Quaternaire, 1997, vol. 51, n" 3, p. 337-346, 5 fig. QUATERNARY RIVER DIVERSIONS IN THE LONDON BASIN AND THE EASTERN ENGLISH CHANNEL D.R. BRIDGLAND* and P.L. GIBBARD, respectively, Department of Geography, University of Durham, South Road, Durham DH1 3LE, United Kingdom, and Quaternary Stratigraphie Group, Godwin Institute of Quaternary Research, Department of Geography, University of Cambridge, Downing Place, Cambridge CB2 3EN, United Kingdom. ABSTRACT The principal river of the Lon­ RÉSUMÉ Les captures quaternaires des ZUSAMMENFASSUNG Fluss-Ablenkungen don basin, the Thames, has experienced a fleuves du bassin de Londres et de la Man­ im Quartàr im Londoner Becken und im number of course changes during the Qua­ che orientale De nombreuses captures ont ôstlichen Àrmelkanal.
    [Show full text]
  • National Geological Screening: London and the Thames Valley
    National Geological Screening: London and the Thames Valley Minerals and Waste Programme Commissioned Report CR/17/101 BRITISH GEOLOGICAL SURVEY MINERALS AND WASTE PROGRAMME COMMISSIONED REPORT CR/17/101 National Geological Screening: London and the Thames Valley R Ellison1, D Schofield1, D T Aldiss2, R Haslam2, M Lewis3, B Ó’Dochartaigh3, J P Bloomfield3, J R Lee4, B Baptie4, R P Shaw5, T Bide5 and F M McEvoy 1Rock type, 2Rock structure, 3Groundwater, 4Natural processes, 5Resources Contributors/editors L P Field, R Terrington, P Williamson, I Mosca, N J P Smith, D E Evans, C Gent, M Barron, A Howard, G Baker, R M Lark, A Lacinska S Thorpe, H Holbrook, I Longhurst and L Hannaford The National Grid and other Ordnance Survey data © Crown Copyright and database rights 7. Ordnance Survey Licence No. 100021290 EUL. Keywords National geological screening, GDF, rock type, structure, groundwater, natural processes, resources, London, Thames. Bibliographical reference ELLISON, R, SCHOFIELD, D, ALDISS, D T, HASLAM, R, LEWIS, M, O’DOCHARTAIGH, B, BLOOMFIELD, J P, LEE, J, BAPTIE, B, SHAW, R P, BIDE, T, AND MCEVOY, F M. 2018. National Geological Screening: London and the Thames Valley Commissioned Report, CR/17/101. 71pp. BRITISH GEOLOGICAL SURVEY The full range of our publications is available from BGS shops at Nottingham, Edinburgh, London and Cardiff (Welsh British Geological Survey offices publications only) see contact details below or shop online at www.geologyshop.com Environmental Science Centre, Keyworth, Nottingham The London Information Office also maintains a reference NG12 5GG collection of BGS publications, including maps, for Tel 0115 936 3100 consultation.
    [Show full text]
  • 2.0 the Natural Landscape of London
    2.0 The Natural Landscape of London London: A Green City? Contrary to perceptions, London is an unusually green city as of how they contribute to the city as a whole. This disconnection ‘natural’ environment. This may be the case for those architectures compared to other major world centres such as New York and Tokyo. between our daily experience of London and its relatively ‘green’ which reject the vernacular – notably modernism, which aimed at Nevertheless, for many, the impression of London is that of a highly character is exacerbated by the prevalence of travel by Underground, an international style − but vernacular architecture has by definition built up urban area, surrounded by less dense residential suburbs, whilst the topography of London, albeit gentle, has largely been an intimate relationship with its locale, whether as a form, such and whilst the Royal Parks are much-loved for their serenity and their disguised by London’s built environment. as the pitched roof, a direct response to frequent rainfall, or in the amenity value, how far we integrate them into our wider perception use of local building materials. Yet it is difficult to think of London’s of London is questionable. Likewise, whilst Londoners may regularly Underlying such perceptions is not only the disparity between architecture as vernacular, even though, to a large extent, London’s use local green spaces such as parks and commons, they are not daily living and travelling and a city-wide perspective but, perhaps built environment is derived from, rather than in opposition to, its necessarily perceived as integral parts of London’s character; private deeper, a fundamental assumption that architecture and urban underlying natural condition.
    [Show full text]
  • High-Resolution Geological Maps of Central London, UK: Comparisons with the London Underground
    Geoscience Frontiers 7 (2016) 273e286 HOSTED BY Contents lists available at ScienceDirect China University of Geosciences (Beijing) Geoscience Frontiers journal homepage: www.elsevier.com/locate/gsf Research paper High-resolution geological maps of central London, UK: Comparisons with the London Underground Jonathan D. Paul Department of Earth Sciences, Bullard Laboratories, University of Cambridge, Madingley Rise, Cambridge, CB3 0EZ, UK article info abstract Article history: This study presents new thickness maps of post-Cretaceous sedimentary strata beneath central London. Received 31 March 2015 >1100 borehole records were analysed. London Clay is thickest in the west; thicker deposits extend as a Received in revised form narrow finger along the axis of the London Basin. More minor variations are probably governed by 14 May 2015 periglacial erosion and faulting. A shallow anticline in the Chalk in north-central London has resulted in a Accepted 21 May 2015 pronounced thinning of succeeding strata. These results are compared to the position of London Available online 25 June 2015 Underground railway tunnels. Although tunnels have been bored through the upper levels of London Clay where thick, some tunnels and stations are positioned within the underlying, more lithologically Keywords: London variable, Lower London Tertiary deposits. Although less complex than other geological models of the London Underground London Basin, this technique is more objective and uses a higher density of borehole data. The high London Clay resolution of the resulting maps emphasises the power of modelling an expansive dataset in a rigorous Lambeth Group but simple fashion. Chalk Ó 2015, China University of Geosciences (Beijing) and Peking University.
    [Show full text]
  • Management of the London Basin Chalk Aquifer Status Report 2018 I Figures
    Management of the London Basin Chalk Aquifer Status Report – 2018 August 2018 Foreword We are the Environment Agency. It's our job to look after your environment and make it a better place - for you, and for future generations. Your environment is the air you breathe, the water you drink and the ground you walk on. Working with business, Government and society as a whole, we are making your environment cleaner and healthier. The Environment Agency. Out there, making your environment a better place. Contents Introduction ........................................................................................................................... 1 1 Overview of the London Basin Aquifer ........................................................................... 1 2 Why we need to manage groundwater levels ................................................................. 5 3 How we manage groundwater levels .............................................................................. 6 4 Recent abstraction trends .............................................................................................. 9 5 Groundwater levels for January 2017 ........................................................................... 12 Recent Changes in Groundwater Levels ......................................................................... 13 Long Term Changes in Groundwater Levels.................................................................... 13 6 Current licensing strategy ...........................................................................................
    [Show full text]