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ENVIRONMENTAL GEOLOGY by GU9jBy8C

VIEWS: 19 PAGES: 12

									ENVIRONMENTAL GEOLOGY
GL 2001.6
This course introduces the concepts of environmental geology within an Earth System.
The course reviews material previously studied in first and second year material courses
for resources, their development and location both globally and within the UK.
Geological Hazards are then evaluated; both natural and manmade. Finally some Global
issues are addressed.

Environmental Geology
What is it?




Reading list

Course Text Book

      Woodcock, N (1994) " Geology and Environment in Britain and Ireland" UCL
       Press

Other Text

      Coats, D. R. (1981) "Environmental Geology" John Wiley
      Keller, E. A. (1976) "Environmental Geology" Merill
      Tank, R. (1973) "Focus on Environmental Geology" Oxford Uni. Press
Course Outline

      Background
      Resources
      Natural Geologic Hazards
      Manmade Hazards - Waste Disposal



Background

      Environmental Geology - What is it?
      Course Concepts

Earth System Sciences

"The Earth's Past as a Guide to the Earth's Future." Woodcock (1995)

      Careers
      Links with other Courses



Resources

      What are they?
      Renewable/Nonrenewable
      Geologic Influence on Resources - UK resources
      Review of Previous courses - Metallic, Non-metallic, water
      Energy Resources - Nuclear
      Energy Resources - Renewable



Geologic Hazards - Causes, Risks, Prediction, Mitigation

      Earthquakes
      Landslides
      Subsidence
      Radon
      Volcanoes

Man-made Hazards - Waste Disposal
      Managed vs. Un-managed Disposal
      History of Waste Disposal
      Types of Waste Disposal
      Problems

Nomenclature

Earth Sciences - the study of the lithosphere and inner Earth

Earth System Sciences - the study of interactions of all environmental components;
lithosphere, hydrosphere, biosphere, atmosphere, magnetosphere, (political sphere?)(fig)

Lithosphere - crust and upper mantle

Hydrosphere - all the waters on face of Earth and in crust

Biosphere - all regions occupied or potentially occupied by living organisms

Atmosphere - the continuous gaseous envelope surrounding the Earth

Magnetosphere - the space pervaded by the Earth's magnetic field

Some Environmental Issues Today

      Fossil Fuels vs. Nuclear Fuels?
      Sensitive Economic Extraction of Resources
      Recycle vs. Energy Consumption
      Hazardous discharge and biodiversity
      Old waste disposal sites and SSSI's
      When is contamination safe?
      Prediction of Geologic hazards
      Global warming or just a lot of hot air ?

read Mellanby, K (1992) "Waste and Pollution, the Problem for Britain". Harper Collins.




Resources - What are they?
Reference during this course is made extensively to the material taught by Drs. Stevens
and MacNeill during the first year courses on metallic and non-metallic materials. Also
references will be made to the first year course on groundwater (G1001).

Non-renewable Resources - review previous courses Geology First Year
Courses
      Base metals - Fig WES G1001
      Precious metals - Fig WES G1001
      Building material - Fig GMcN G1001
      Hydrocarbons - Fig GMcN G1001, Oil and Gas Resources, USGS
      Nuclear

Renewable Resources (Renewable energy, CREST)
Renewable

      Water (CRB G1001)
      Solar
      Geothermal
      Biomass(biomass, CREST)
      Wind(Wind Power, CREST)

Resource Geology of Britain

      Global and UK consumption
      Global and UK reserves
      Resources and their locations in the British Isles
      Energy consumption in the UK
      Energy resource distribution in the UK

To find out more about energy in the UK and elsewhere in the World visit the following
sites:

Energy and the environment at;

http://www.wam.umd.edu/~tfagan/enrgyenv.html

EPA - US Environmental Protection Agency;

http://www.epa.gov/

Renewable Energy;

http://www.eren.doe.gov/

Global change;

http://www.usgcrp.gov/

UK National Energy Foundation;

http://www.natenergy.org.uk/
UK Nuclear Industry

http://www.users.zetnet.co.uk/n-base/

http://www.ukaea.org.uk/

UK Solar Energy Society;

http://www.demon.co.uk/tfc/uk-ises.html




Energy Resources

Potential Renewable Energy resources for the UK

      Hydroelectric 0.7%
      Wave 6%
      Solar 6%
      Tidal 6%
      Biomass 13%
      Wind 22%



Nuclear Energy - non-renewable energy

      Resources
      World reserves concentrated in few countries. China and former Soviet Union
       aside present levels of consumption will last only 50 years.
      World resources estimated at 1860 thousand tonnes

Nuclear Energy - World Reserves

Nuclear Energy - Fuel Cycle



Geothermal Energy - Renewable/Partially Renewable

Types of Geothermal Energy:
Geothermal Aquifer -

     low enthalpy system
     average heat flow
     high heat gradient
     low thermal conductivity e.g. mudstones
     few km deep,
     heat exchange by pumping hot saline water

Hyperthermal Systems (Geothermal, US DOE)

     high enthalpy
     high heat flow (300mWm-2) e.g. intrusions
     ground water directly heated and moved by hydrothermal convection
     water trapped and taped via fracture system
     water steams on release of pressure
     renewable on human time scale due to great heat

Geothermal Hot-dry Rock (e.g. Cornwall)

     higher heat production than average
     pump water into induced fracture system
     problems with keeping fracture system active
     may be important for the future but technically difficult

Hazards

     Natural Hazards
     Man-made Hazards

Study Methods

     Causes - identification of processes
     Risk areas - mapping hazard areas
     Prediction - monitoring hazard development
     Mitigation - hazard engineering

Natural Geologic Hazards

     Earthquakes
     Landslides
     Subsidence
     Radon
     Volcanic
Landslides
Types of Landslide (fig)

      fall - rock, topples
      creep
      flow
      slide - rotational, debris, mud, rock
      slump - sagging
      compound

Causes (fig)

      loading of head - sedimentation, man-made load
      strength reduction - weathering, bioremoval
      wetting
      undercutting
      change in pore pressure
      ground instabilities from external sources - earthquakes

Landslides - Landslide Classification
The National Landslide Review

Table insert

Groups of Landslide failure

      First time Failure - previously unsheared ground. Large rapid displacements. e.g.
       Holbeck Hall Slide. (case history)
      Failures on Pre-existing Shear Surfaces - surfaces often non-landslide origin. e.g.
       slopes activated by inappropriate earthworks, Aberfan, 1966. (video)
      Reactivation of Previous Slips - new movements on pre-existing surfaces. (fig
       Mam Tor)
      Seismic Induced Slips - all of the above induced by high seismic activity.

(see: Auburn Dam - USGS)

Risk Areas

      steep slopes
      non vegetated areas
      lose soil areas
      most coastal areas
      high seismic potential areas
For further information on hazard risk areas and prediction

see Hazards - lanslides home page, USGS

Prediction

      surface/subsurface geological mapping (fig)
      visual inspection - slope analysis (fig)
      water levels
      tilt meters
      strain gauges
      passive seismic monitoring

Mitigation

      lower moisture content (fig)
      reduce slope angles
      construction of artificial barriers
Subsidence
subsidence - downward displacement of surface material caused by natural
or artificial removal of underlying support (collapse) or by compression of
ground (consolidation)

                             disaster when this is rapid




Subsidence

hydrocompaction - reduction in dry strength of material by addition of water tend to be
evident in sediments with high void ratios and a clay content of approximately 12%

Piping - subsurface flow of water under high hydraulic heads. Erodes channels in sands

Karsting - solution of cavities in (mainly) limestones

Mantled Karsts - layer of soil over limestone karst masks presence of karst beneath

Thermokarst - karsting in regions with permanently frozen ground. Differential melting
of subsurface.

Volcanokarst - piping in volcanic terrain

Consolidation
consolidation - natural compression of saturated sediment or rock under
influence of static load

primary consolidation - initial stress causes water expulsion, compression of
material, usually rapid event




secondary consolidation - adjustment of internal structure, further
compression, usually long term event
Effective stress - (Terzaghi, 1936)




Subsidence - High Risk Areas

      plate boundaries
      carbonate geology areas
      mining areas

Prediction

      surface and sub-surface geology mapping
      large-scale strain guages
      precise geodetic levelling - satelite surveying?
      cavity detection using geophysical methods
     mapping man-made hazards - underground mining, (Case Histories, Norwich,
      Glenrothes practical class)

Mitigation

     subsidence risk maps
     building regulations
     fluid injection - repressurization of the ground

								
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