3.4 The Human Impact

• The human impact is of great importance
• Landforms can be created by

  • Constructional activities (tipping, excavation and hydrological interference)
  • Farming
• Hillsides have been terraced in many parts of the world for centuries
• Pollution


  The contamination of the Earth/atmosphere system to such an extent that normal environmental processes are adversely affected
• Elements involved in pollution

  • Disagreeable
  • Noxious
  • Toxic
  • Harmful
  • Objectionable
• Pollution can be natural, such as from volcanic eruptions, as well as human in origin
• Pollution can be deliberate or accidental
• Changes in local climate


  Can intensify weathering processes
• Changes in the nature and rate of weathering


  Are closely linked to air quality
• Increased emissions of SO2 (from the burning of fossil fuels) have led to higher levels of sulfuric acid
• Chemical reactions with SO2 can create salts, such as calcium sulfate and magnesium sulfate, which are able to chemically weather rocks
• Burning of fossil fuels and deforestation

  Has raised atmospheric levels of CO2, increasing the potential for carbonation–solution
• Increased acidity in rain water

  Due to SO2 and nitrogen oxides in the atmosphere
• Increased lighting in caves

  Allows plants to grow, leading to biological weathering and increased levels of organic acids
• Rates of mass movements can be altered by building, excavation, drainage or agriculture, all of which can destabilise slopes
• Some mass movements are created by humans piling up waste soil and rock into unstable accumulations that move without warning
• Landslides can be created by undercutting or overloading
• Methods of controlling mass movement

  • Grading or benching the slope to flatten it
  • Drainage
  • Reinforcement of rock walls by grouting with cement or using anchor bolts
  • Covering of wall with steel mesh
  • Drainage of surface water with ditches
  • Sealing surface cracks to prevent infiltration
  • Sub-surface drainage
  • Rock or earth buttresses at foot
  • Retaining walls at foot
  • Pilings through the potential slide mass
• In urban areas slope modification is often very significant, given the need for buildings and roads to be constructed safely
• Even on flat sites, large modern buildings generally involve the removal of material to allow for proper foundations
• Slope modification tends to increase as construction moves onto steeper slopes
• The steep slopes, devoid of soil and vegetation, are potentially much less stable than the former natural slope and are, in times of intense rainfall, susceptible to small but quite damaging land slips
• Environmental impacts of mining

  • Habitat destruction
  • Disposal of waste rock and 'tailings'
  • Water pollution
  • Air pollution
  • Noise
  • Vibration
  • Visual intrusion
  • Dereliction
• Producing 1 tonne of copper creates over 100 tonnes of waste rock
• Even the production of 1 tonne of china clay (kaolin) creates 1 tonne of mica, 2 tonnes of undecomposed rock and 6 tonnes of quartz sand
• Sulfur dioxide (SO2) and nitrogen oxides (NOx) are emitted from power stations, industrial complexes, vehicles and urban areas
• Acidification


  1. Sulfur dioxide (SO2) and nitrogen oxides (NOx) fall directly to the ground as dry deposition

  2. SO2 and NOx are oxidised to form sulfuric acid (H2SO4) and nitric acid (HNO3)

  3. Acids dissolve in cloud droplets to form acid precipitation (wet deposition)
• The worst-hit areas used to include Scandinavia and eastern North America
• The future trends are likely to see increased sulfur emissions in NICs (newly industrialising countries) such as China, India and Brazil
• Effects of acid rain

  • Acidified lakes are characterised by an impoverished species structure
  • Sulfur dioxide interferes with the process of photosynthesis, affecting coniferous trees
  • Acid rain corrodes metal and stonework, making the maintenance of buildings more costly
• Possible solutions to acid rain

  • Using low-sulfur fuels (oil/gas or high-grade coal)
  • Removing sulfur from waste gases after combustion – flue gas desulfurisation (FGD)
  • Burning less fossil fuel (this requires a government initiative in order to switch to nuclear or HEP)
  • Burning coal in the presence of crushed limestone in order to reduce the acidification process