ESS 4.1-4.2

water cycle

• most water on earth is: saltwater

• water cycle storages:

  • oceans
  • soil mousture
  • ice caps
  • rivers/lakes

• Transformation: change in state

• transfer: chnage in location

• water cycle transformations:

  • evaporation
  • sublimination: solid → gas
  • deposition: gas → solid
  • condesation
  • melting
  • freezing

• water cycle transfers:

  • surface run off
  • flooding
  • precipitation
  • absorption

• water cycle:

  

• vegetation (plants) : can slow movement of water

• percolation: water flows into the ground, under influence of gravity

• aquifer: underground zone

• groundwater: largest freshwater source

ocean circulation systems

• Global conveyor belt: driven by differences in water density
  • cold water is more dense
  • saltier water is more dense
  • water: high heat capactity → oceans warm & cool slowly
  • atmosphere: low capacity
  • how can global warming impact conveyor belt?
  • if oceans become warmer they hold less carbon dioxide so with more co2 in the atmosphere, temperature rises even more

human act. on water cycle

• overall: changes in land use (human activity) impact water cycle
• deforestation:
  • the trees absorb the water → forest acts as sponge
  • with no forest → more runoff → floods
• urbanisation:
  • water cannot pass through
  • runoff catches pollutants from cities → lakes & streams
  • high flood risk → no trees
• Agriculture:
  • biggest water usage
  • there is fertelizer and pesticide runoff
  • excessive irrigation → poor soil
  • how to avoid water pollution from this:
  • limit fertelizers & pesticides

demand for water

• why?
  • population growth
  • more meat based diet → the production of meat uses more water
  • Urbanization increase
• water stress: when demand exceeds availablity

managing water resources

• reservoirs: used to collect/store water → built by damming rivers & flooding valleys
  • benefits:
  • flood control
  • water quality
  • cons:
  • chnage of habitat ecosystem
  • relocation of people & species
• Desalination: makes freshwater from saltwater
  • expensive
• greywater:
  • using water from baths, washing machine
  • can be used for toilet flushing, not ok to drink