APES CH. 13 & 17

• Properties of Water:

  • Melting/Freezing Point 0oC
  • Boiling Point: 100oC
  • Universal Solvent: Due to its polarity and Hydrogen bonding (Dilute/Disperse/Dissolve) pollutants
  • Polar Covalent Molecule with partial charges on H and O
  • An effective filter of shorter UV wavelengths
  • Higher density in liquid form than its solid form due to Hydrogen bonding
• • Polar Covalent Molecule with partial charges on H and O
• • Melting/Freezing Point 0oC
• • Boiling Point: 100oC
• • Universal Solvent: Due to its polarity and Hydrogen bonding (Dilute/Disperse/Dissolve) pollutants
• • Higher density in liquid form than its solid form due to Hydrogen bonding
• Surface water = water on the surface like streams and lakes
• • Surface Water = Surface runoff and watershed basin (Lake, River, Stream)
• Ground water = water that saturates soil, sand, and rock beds, supplying springs and wells, like aquifers
• • Aquifers = Recharged naturally by rain or by nearby surface water - an underground layer of water-bearing permeable rock
• • Zone of Saturation - Spaces in soil below a certain depth are filled with water
• • Water Table - top of the zone of saturation
• ⅔ of surface runoff are lost due to seasonal flooding and the remaining ⅓ is the reliable runoff
• • Worldwide Average - freshwater use
  • 70% for Irrigation and Livestock
  • 20% for Industrial use
  • 10% Cities and Residence
• Many River Systems are highly stressed

  • Nile, Jordan, Yangtze, Ganges
• 30% of Earth’s land area experiences severe drought
• Ways to increase Water Supply

  • Dams and Reservoirs
  • Saltwater Desalination
  • Water Transfer/Diversion
• dam is a physical structure that retains water; a reservoir is the water body that is created by a dam.
• Dams and Reservoirs PROS

  • Capture and store runoffs which increases reliable runoff
  • Release runoff for flood control, generate electricity, supply irrigation water, and recreation
• Dams and Reservoirs CONS

  • Habitat destruction displace not just species but also humans
  • Impair ecological services of rivers such as nutrient distribution
  • Sediment buildup can fill it within 50 years
  • Endanger animals and plants
• Problems that could arise from using dams

  1. Faulty dams leak water
  2. They can’t work when the water level is too low
  3. flood large areas
  4.  force people to relocate
  5. threaten freshwater biodiversity
• Environmental impacts of dams

  • disrupt subsistence fisheries,
  •  leave rivers dry – affecting the ecosystem.
  • water, soil, air quality
  • wildlife habitat
• Groundwater CONS

  • Over use leads to depletion or lowering of water tables
  • Arid countries far from surface water depends on aquifers too much
  • Limits food production which will increase prices
  • Land Subsidence
  • Groundwater overdraft in coastal region will risk saltwater intrusion
• • Land Subsidence = When the ground sinks, causing buildings to collapse.
• Groundwater PROS

  • Cost-effective
  • Good for places with high water tables
  • Irrigation
  • Industrial and other use
• Problems that could arise from using Groundwater

  • drying up of wells
  • reduction of water in streams and lakes
  • deterioration of water quality
  • increased pumping costs
  • land subsidence
• Environmental impacts of groundwater usage

  • lowered water tables
  • saltwater intrusion in aquifers
  • lower streams and lakes
  • less biodiversity
• Types of desalination methods are Distillation or Reverse osmosis
• Reverse osmosis performs water filtration by passing it through multiple stages of filtration stripping off all the minerals. In the final filtration stage, it adds healthy minerals back into the water
• Distillation, on the other hand, also purifies water but doesn't add healthy minerals to the water
• Cost of desalination: $1000 per cubic meter of water

  High cost, high energy usage, and large amounts of salty wastewater
• Water Transfer/Diversion = Transfering/diverting water from one place to another through canals or aqueducts
• Water Diversion

  • Loss of water from evaporation and leaks as the water is moved
  • Environmental Degradation by building them
• Aral Sea & Colorado River

  There are several similarities and differences between the effects of human alterations on the Colorado River and the Aral Sea. Both have dams and canals, and both fail to reach the ocean. The Colorado River supplies both agriculture and urban areas. And the rivers of the Aral Sea are diverted primarily for agricultural areas. The water levels are depleting and the fish are dying.
• The main difference between these two examples is that the Colorado River has been able to maintain some flow while the Aral Sea has not.
• Groundwater pumping rates exceed recharge rates leading to declining groundwater tables and reduced availability of this resource
• Irrigation is using water for crops that is not rainwater. Irrigated water can be pumpedfrom groundwater, aqueducts and other sources
• Waterlogging occurs when too much water is left to sit in the soil. This raises the water table and suffocates plants (prevents gas exchange)
• Furrow Irrigation:

  Description: Ditches between crop rows that are filled with water.

  Benefits: Inexpensive and easy

  Drawbacks: 1/3 of the water is lost to evaporation and runoff
• Flood Irrigation:

  Description: Flooding of a field with water. Sometimes used with furrows.

  Benefits: Inexpensive and easy

  Drawbacks: 20% loss of water to evaporation and runoff. Can waterlog soil