Chapter 3 - Global Distribution Resources and Use

Water Distribution and Properties

• 70% of Earth’s surface is covered in water.
• 97% of water is located in the oceans.
• 3% of water is freshwater, most of the freshwater is located in the ice caps and glaciers.
• Unique properties of water
  • Water has a high boiling point
  • A lot of energy is needed to evaporate water
  • Water dissolves many compounds
  • Water expands as it freezes
  • Water adheres to many solid surfaces

Freshwater

• Freshwater
  • The places with the highest amount of freshwater are the places with high precipitation and small populations.
  • The places with the lowest amount of freshwater are the places with low precipitation and large populations.
  • The use of freshwater is growing at twice the rate of population growth.

Aquifers

• Aquifers
  • Geologic feature that contains water in quantities sufficient to support a spring or well.
  • Holds 30 times more water in the US than all US lakes and rivers combined.
• Important terms
  • Confined Aquifer - an aquifer below the land that is saturated with water.
  • Recharge Zone - The area above an aquifer that supplies water.
  • Unconfined Aquifer - An aquifer where the upper water surface is at atmospheric pressure
  • Unsaturated Zone - The zone immediately below the land surface that is not totally saturated with water.
  • Water Permeability - The ability of a material to allow passage through rocks with water
  • Water Table - The level below that ground is saturated with water.

Types of Ice

• Glaciers
  • Body of dense ice that only forms on land.
  • 99% of glacial ice is contained in ice sheets in polar regions.
  • Largest reservoir of freshwater in the world.
• Ice Sheets
  • Mass of glacial ice that is greater than 20,000 square miles in area.
  • The only ice sheets are Antarctica and Greenland.
• Ice Shelves
  • Thick floating platform of ice that forms when a glacier or ice sheet flows down to a coastline and onto the ocean surface.
  • Only found in Antarctica, Greenland, and Canada
• Sea Ice
  • Frozen seawater.
  • It floats on the ocean surface.
  • It is found primarily in the Northern Hemisphere.

Oceans

• 71% of the Earth’s surface is covered in oceans.
• More than half of this area is under 10,000 feet.
• Oceans have a significant effect on the biosphere, because oceanic evaporation is the primary source of precipitation.
• Oceanic Circulation
  • Heat is transferred to the equator by ocean currents.
  • Warm waters near the surface and cold water deeper in the ocean move by convection currents.
• The Great Ocean Conveyor Belt
  • There is constant motion in the form of a global ocean.
  • Cold water sinks to the bottom of the ocean
  • Warm water rises to the surface.
  • Cold water will go south towards the Antarctic
  • Warm water will come back up to the Pacific
  • This conveyor belt helps regulate the amount of sea ice in polar regions.

Agricultural, Industrial, and Municipal Use

• There are 3 types of water withdrawal
  • Agricultural
  • Industrial
  • Municipal
• Water Shortages
  • The rate of water consumption is growing twice as fast as population growth.
  • Water is a limited factor as it limits the amount of food that can be produced in a region.
• Water Diversion
  • Groundwater is the largest source of freshwater in the world.
  • Freshwater is being diverted into many different purposes.
  • Environmental consequences from this diversion can be
  • Concentration of salts and minerals and pollutants may increase
  • Can reduce the habitat for fish and can impact feeding and spawning success
  • Temperature and oxygen levels can increase.
  • A reduction of the native populations of animals and plants.

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