14.3 Mining and quarrying impacts on landscapes

Mining and quarrying dramatically reshape landscapes, altering topography and accelerating erosion. These activities create massive excavations, waste piles, and artificial slopes, leading to increased sediment transport and potential instability. The impacts extend far beyond the mine site, affecting river systems and ecosystems.

Reclamation efforts aim to restore mined lands, but challenges persist. Geomorphic design principles and revegetation strategies help create more stable and natural landforms. However, long-term effects on hydrology, sediment budgets, and water quality can linger for decades, highlighting the need for careful management and monitoring of mining's impacts on Earth's surface.

Geomorphic Impacts of Mining

Landscape Alteration and Topographic Changes

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  Spoil heaps above the Standedge tunnels © John H Darch :: Geograph Britain and Ireland View original

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  Spoil heaps from Harrowbank Quarry © Mike Quinn :: Geograph Britain and Ireland View original

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  Spoil heap from old lead mine (2) © Mike Quinn :: Geograph Britain and Ireland View original

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  Spoil heaps above the Standedge tunnels © John H Darch :: Geograph Britain and Ireland View original

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  Spoil heaps from Harrowbank Quarry © Mike Quinn :: Geograph Britain and Ireland View original

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Top images from around the web for Landscape Alteration and Topographic Changes

• 

  Spoil heaps above the Standedge tunnels © John H Darch :: Geograph Britain and Ireland View original

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• 

  Spoil heaps from Harrowbank Quarry © Mike Quinn :: Geograph Britain and Ireland View original

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• 

  Spoil heap from old lead mine (2) © Mike Quinn :: Geograph Britain and Ireland View original

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• 

  Spoil heaps above the Standedge tunnels © John H Darch :: Geograph Britain and Ireland View original

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• 

  Spoil heaps from Harrowbank Quarry © Mike Quinn :: Geograph Britain and Ireland View original

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• Surface mining and quarrying remove overburden and extract minerals altering natural landscapes and topography
• Open-pit mining creates large excavations resulting in steep pit walls and extensive waste rock piles prone to instability and erosion
• Strip mining techniques (mountaintop removal) modify landforms by removing entire hilltops and filling adjacent valleys with overburden
• Quarrying for dimension stone or aggregates creates large geometric excavations in bedrock altering local drainage patterns and groundwater flow
• Creation of spoil heaps and tailings piles introduces new unstable landforms susceptible to mass wasting and erosional processes
• Mining operations accelerate weathering processes by exposing fresh rock surfaces and altering local microclimates
  • Increased surface area of fractured rock leads to more rapid chemical weathering
  • Changes in temperature and moisture regimes can enhance physical weathering (freeze-thaw cycles)

Erosion and Sediment Transport

• Removal of vegetation and soil during mining activities increases potential for soil erosion and sediment transport
  • Bare soil surfaces are more vulnerable to raindrop impact and surface runoff
  • Lack of root systems reduces soil cohesion and stability
• Increased erosion rates impact both on-site and off-site environments
  • On-site: formation of rills and gullies on exposed surfaces
  • Off-site: sedimentation in streams and rivers, affecting water quality and aquatic habitats
• Altered topography can concentrate surface runoff leading to accelerated erosion in specific areas
  • Steep slopes of open pits or waste piles are particularly susceptible
• Fine particulate matter from mining operations can be transported by wind causing air quality issues and dust deposition in surrounding areas
  • Example: coal dust from open-pit coal mines affecting nearby communities

Mine Waste and Slope Stability

Geotechnical Challenges of Mine Waste

• Mine waste disposal creates artificial slopes and landforms composed of unconsolidated or poorly consolidated materials increasing susceptibility to instability
• Physical properties of mine waste influence slope stability and erosion potential
  • Particle size distribution affects internal friction and drainage characteristics
  • Cohesion determines the strength of inter-particle bonds
  • Angle of repose sets the maximum stable slope angle for loose materials
• Tailings dams and impoundments pose unique geotechnical challenges with potential for catastrophic failure
  • Liquefaction risk during seismic events or due to high pore water pressures
  • Overtopping during extreme weather events can lead to dam breach and tailings release
• Chemical composition of mine waste affects slope stability through processes like acid mine drainage
  • Acidic conditions weaken rock structures and accelerate weathering
  • Dissolution of minerals can create voids and reduce overall stability

Erosion and Sediment Yield from Mine Waste

• Waste rock dumps and overburden piles are prone to surface erosion especially during heavy rainfall events
  • Sheet erosion on upper surfaces of waste piles
  • Rill and gully formation on steep slopes
• Increased sediment yields in nearby water bodies due to erosion of mine waste
  • Suspended sediment loads in streams and rivers
  • Sedimentation in lakes and reservoirs reducing storage capacity
• Geometry and construction methods of waste disposal facilities influence long-term stability
  • Bench height affects local slope stability
  • Overall slope angle determines global stability of the waste pile
  • Compaction techniques improve material strength and reduce infiltration
• Revegetation efforts on mine waste slopes can improve stability and reduce erosion rates
  • Challenges include poor soil conditions and potential toxicity of waste materials
  • Selection of appropriate plant species tolerant to site-specific conditions

Reclamation of Mined Landscapes

Landform Reconstruction and Ecosystem Rehabilitation

• Reclamation strategies aim to return disturbed land to a stable productive and ecologically viable state
• Geomorphic landform design principles create more natural and stable landforms
  • Integration with surrounding landscape reduces visual impact
  • Mimicking natural drainage patterns improves long-term erosion resistance
• Soil reconstruction and amendment techniques crucial for establishing vegetation
  • Topsoil salvage and replacement
  • Addition of organic matter to improve soil structure and nutrient content
  • pH adjustment for acid-generating materials
• Hydrologic restoration re-establishes drainage networks and wetlands
  • Construction of stream channels with appropriate dimensions and sinuosity
  • Creation of retention ponds to manage surface runoff
  • Wetland development to improve water quality and provide habitat

Revegetation and Monitoring Strategies

• Revegetation strategies consider native species selection soil conditions and potential long-term climate changes
  • Use of pioneer species to stabilize soil and improve growing conditions
  • Gradual introduction of climax species to promote ecosystem succession
• Monitoring programs assess success of reclamation efforts over time
  • Measurements of erosion rates using erosion pins or sediment traps
  • Vegetation cover surveys to track plant establishment and diversity
  • Water quality monitoring to evaluate improvement in runoff characteristics
• Effectiveness of reclamation limited by factors such as soil compaction acid mine drainage and toxic elements
  • Deep ripping or other decompaction techniques to improve root penetration
  • Treatment systems for acid mine drainage (limestone drains bioreactors)
  • Phytoremediation using metal-accumulating plants to remove contaminants

Mining's Impact on River Systems

Hydrological and Morphological Changes

• Mining activities alter watershed hydrology by modifying surface and subsurface flow paths
  • Changes in stream discharge patterns (increased peak flows reduced baseflow)
  • Disruption of groundwater-surface water interactions
• Increased sediment loads from mining areas cause aggradation in river channels
  • Alteration of channel morphology (widening shallowing)
  • Increased flood risks in downstream areas due to reduced channel capacity
• Changes in sediment supply disrupt natural equilibrium of river systems
  • Channel incision in sediment-starved reaches downstream of mining operations
  • Lateral migration and bank erosion in response to altered sediment loads
• Large-scale mining operations alter regional sediment budgets
  • Creation of sediment sinks (pit lakes tailings impoundments)
  • New sediment sources (waste dumps exposed hillslopes)
  • Potential impacts on coastal processes in mining regions near the coast

Long-term Ecological and Water Quality Impacts

• Fine sediment pollution from mining operations affects aquatic ecosystems
  • Impacts on water quality (increased turbidity reduced light penetration)
  • Reduced habitat availability for benthic organisms and fish spawning
  • Changes in species composition favoring sediment-tolerant species
• Introduction of contaminants associated with mine waste affects water quality and sediment chemistry
  • Persistence of heavy metals and other pollutants for decades or centuries
  • Bioaccumulation of contaminants in aquatic food webs
• Legacy effects of historical mining activities continue to influence modern river systems
  • Remobilization of contaminated sediments during flood events
  • Ongoing acid mine drainage from abandoned mines
  • Consideration of mining legacy in current management and restoration efforts
  • Examples: (Rhine River Germany) (Clark Fork River Montana)