Water World Geography Notes

• Input
  • Precipitation: moisture falls from clouds as rain, snow, hail, sleet etc
• Outputs
  • Evaporation: liquid changes to gas due to sun's energy
  • Transpiration: trees lose water through pores in leaves
  • Rivers: flow of water usually downhill to an ocean
• Transfers
  • Infiltration: water moves from the surface into the soil beneath
  • Run-off: water flows overland
  • Through-flow: water flows through soil to a river or sea
  • Groundwater flow: water flows horizontally through soil and rock
  • Percolation: movement of water from soil to rocks beneath
• Stores
  • Groundwater: water is stored underground in rocks after percolation
  • Surface storage: water stored on Earth's surface - lakes, puddles etc.
  • Interception: leaves on trees capture precipitation

• Oceans - 97%
• Glaciers - 2%
• Groundwater - 0.7%
• Lakes - 0.1%
• Soil - 0.005%
• Rivers - 0.0001%
• Living organisms - 0.0004%

Problems

• Oceans can't be used as they're salt water - which causes dehydration
• Glaciers are frown so would need energy to heat them
• There's is very little from lakes and rivers
• Water found in soil is contaminated by siltation
• Living organisms can't have water extracted from them!

Most water is abstracted from groundwater as infiltration makes it clean and there's less litter/pollution. Large amount of water infiltrates and it can't evaporate.

• Population is increasing: need more water for hygiene, washing etc.
• Used more in irrigating crops to feed growing population
• Used more in growing industry e.g. steel and paper
• Urbanisation means by 2025 60% will live in urban areas and water and sanitation infrastructure won't be able to cope
• Tourism e.g. swimming pools and golf courses use lots of water
• Used for HEP to provide energy

• Facts
  • Arid land in sub-Saharan Africa, near equator so high temperatures
  • Very little rainfall (250mm-450mm per year)
  • Precipitation mainly in 1-2mths so very little for the rest of the year
  • Mainly LEDCs - growing pop. so increasing demand for water
  • Since 1970 the water supply has been below average
• Problems
  • Rain falls as torrential downpours so causes flooding
  • Grasses die, soil becomes impermeable as it dries and cracks, this means water can't infiltrate so it's lost as run-off (desertification)
  • Crops can't survive with such little water - reduced yield - starvation
  • Subsistence farmers can't grow enough to feed family
  • Livestock increase by 40% in rainy season causing overgrazing and the land can't support such numbers in dry season
  • Drought causes seasonal rivers and water holes to dry up
  • The water table falls as groundwater is used
  • Both physical and economic water scarcity: limited supply and people are very poor so can't afford it

• Higher temperatures cause even more irregular weather conditions
• Even less precipitation
• More evaporation so rivers and surface storage dry up
• Rising sea levels may contaminate groundwater with salt water
• As land becomes more arid, sand and dust storms may cause more damage to humans and property