Water World

The Planet
1. Lakes and Rivers 0.3%
2. Groundwater/ permafrost 30.8%
3. Glaciers/snow cover 68.9%
4. Hydrosphere
  1. 97.5% Saltwater (1,365,000,000 km 3)
  2. 2.5% Freshwater (35,000,000 km 3)
  3. Hydrological Cycle
    1. Water is recycled through a number of processes.
      1. Water circulates through the biosphere and back to the atmosphere.
    2. Evaporation
      1. Transfer of water from liquid to gas
        Depends on the temperature; higher: more
    3. Transpiration and Evapotranspiration
      1. Liquid water from plants returns to atmosphere as a gas
    4. Condensation
      1. Water vapour becomes water
        When cooled
        Result is clouds or mist/fog
    5. Precipitation
      1. Rain/snow/hail, etc, from clouds.
    6. Surface run off and groundwater flow
      1. Precipitation reaches the ground and infiltrates into the ground OR will run along the surface of the ground.
        Runs into rivers
    7. Streamflow
      1. Groundwater flow/surface run off reaches rivers/streams and flows to oceans
Insufficient water supply
1. Why?
  1. Rising demand due to changing land use. EG: Commercial farming
  2. Rising demand due to population increase
  3. Falling supply due to climate change
    1. Leads to water stress
  4. Falling supply as neighbouring countries take water from rivers on or near borders
  5. Increased industry and farming demand more water
  6. Increase in wealth means more people have to power washing machines, etc
  7. Global warming reduces rainfall
  8. Higher Temperatures increases evaporation
2. CASE STUDY: SAHEL
Water pollution
1. 5 million people die a year of water-borne diseases
2. Water is polluted by industrial waste
  1. Toxic waste from mines
    1. Toxic runs into rivers and groundwater, in Heap-leach mining
      1. Now banned in many US states to prevent this.
  2. Plant fertilisers
    1. Nitrates run into rivers and lakes, causing eutrophication
      1. Kills animals due to lack of oxygen as plants and algae cannot photosynthesise
  3. Chemical waste
    1. Water can be polluted by poisonous arsenic, flourine and sulphates, such as in China where 980 million people drink this everyday
  4. Radioactive Waste
    1. Nuclear waste remains dangerous for thousands of years
      1. Storing it is risky as leaks could occur
Human interference
1. Deforestation
  1. Without trees, surface run off and transpiration cannot occur
  2. Infiltration decreases
  3. Can cause floods, as trees cannot interfere with rainfall
2. Over-abstraction
  1. People take more groundwater than is being replaced by precipitation
  2. Farmers use pumps which are supplied with cheaper electricity
  3. There is none left for local people if all abstracted by companies
Water management projects
1. Dams
  1. Generate HEP
  2. Control water flow
  3. Reduce floods
  4. Water stored in reservoirs can be used for local people and farmers
  5. Can disrupt local people and habitats
  6. Very costly
  7. CASE STUDY: 3 gorges dam
2. Small scale management
  1. Rainwater harvesting
    1. Cheap to set up and run
    2. Can be managed by locals

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hydrological_cycle (image/jpg)

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Water World

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