APES 5.10 Impacts of Urbanization

Enduring Understanding:

• When humans use natural resources, they alter natural systems. 

Learning Objective:

• Describe the effects of urbanization on the environment.

Essential Knowledge:

• Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle.
• Urbanization, through the burning of fossil fuels and landfills, affects the carbon cycle by increasing the amount of carbon dioxide in the atmosphere.
• Impervious surfaces are human-made structures – such as roads, buildings, sidewalks, and parking lots – that do not allow water to reach the soil, leading to flooding.
• Urban sprawl is the change in population distribution from high population density areas to low density suburbs that spread into rural lands, leading to potential environmental problems.

Urbanization

• The shift away from rural, agricultural based living into a human settlement with high population density
• Doesn’t have to do with how many people there are, just the density
• Jobs in these areas are not agricultural in nature
• Lots of human constructions and infrastructure
• The home is close to the workplace, medical and schooling resources, grocery and food needs, etc.
  • These are either reasonably close by foot or by transit (public/personal)
  • Public transit is good for the environment by moving more people with less energy
• Space is used very efficiently, often building up instead of out

Consequences

Water Cycle

• A lot of water is needed for so many people in one spot
  • This often involves the diversion or disruption of normal water flow
  • Anytime you disturb waterflow, you are altering habitats and affecting ecosystems
  • Dams, in particular, affect both upstream and downstream
• When an aquifer supplied by the ocean is drawn upon continuously, the freshwater is depleted and saltwater rises to replace it
  • Eventually, salt water is being drawn up, which is unusable unless it goes through an intensive and expensive desalinization process

Impermeable Surfaces

• Water does not infiltrate through pavement/concrete
• This means the water is not replenishing groundwater and runs off
  • When water runs off, it also picks up anything on the ground and distributes that downstream
• The water collects in a low point or runs into other bodies of water
• It picks up the chemicals we use on our lawns, physical trash and debris, waste, etc.
• From a climate perspective, the precipitation and water that deposits is not staying where it drops
  • This destabilizes the local weather
• The pollutants that water collects can also end up in drinking water
• Heat islands can often occur due to these surfaces
  • Surfaces like pavement have very low albedo, meaning they heat up very quickly by absorbing so much heat
  • A lot of heat is taken in, stored, and them emenated throughout the day and night

Carbon Cycle

• Cities have a lot of electricity running through them, meaning fossil fuels are probably providing that energy
• Lots of people means lots of waste, which needs to be disposed of
  • Waste also releases greenhouse gasses

Air Quality

• Air pollution (unit 7) can harm the health of various organisms

Urban Sprawl

• Eventually cities can no longer build upwards, or development doesn’t for certain reasons, so people settle further and further outwards
• This creates suburbs
  • This can create lower-density areas where personal car use is more common
  • Which uses more fossil fuels, takes up more land, harms more habitats, more impermeable surfaces, etc.

Remediation

• Incorporating vegetation is a critical and wide-reaching solution
  • Helps with habitat restoration, lowering heat, reducing some use of impermeable surfaces, recharge areas for groundwater, taking in carbon dioxide
• Extending mass-transit
• Permeable pavements have recently been invented and implemented
• Urban planning sustainably and thoughtfully
• Brownfields, or abandoned industrial constructs, can be torn down and productive replacements can be put in
• A lot of these remediations also foster communities, improve human mental and physical health, and overall improve quality of life