CH

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