Water budgets

• global water budget= balance between water being evaporated from oceans and precipitated onto the land
• limited water for human use

  • only 2.5%= freshwater and <1%= accessible for direct human use
  • access and quality of water differs depending on location
  • earth geology plays a big part in affecting water availability
• water store residence time

  • water found in oceans = stored for longer then the short amount of time that water is held in atmosphere
• non renewable stores

  • fossil water= non renewable, untouched, ancient freshwater store found beneath deserts and polar areas
  • new tech allows us to access more of this water eg new drilling and satellite tech
  • cryosphere = non renewable as it continues to melt
• Polar hydrology

  • aka cryosphere
  • little vegetation bc of low temp and limited light so plant growth is reduced
• during winter

  • round, lakes and rivers= frozen in cryosphere
  • winter snow and ice = 85% of solar radiation is reflected
  • permafrost = soil permanently frozen
• during spring/summer

  • frozen water thaws = rapid surface runoff = increased evaporation
  • ice and soils thaw, biogenic gases released into atmosphere
• Tropical hydrology

  • little seasonal variation bc of consistent temp high rainfall and consistent sunlight
  • high density of vegetation collects most of precipitation
  • ~50% of precipitation returned via evapotranspiration
  • able to generate own water cycle due to conventional rainfall ( forest floor = warm so air n surface heats up and expands, air rises and condenses=rain clouds)
• tropical rainforest deforested

  • deforestation reduces evapotranspiration= reduces precipitation levels and water supply as less water is being put into the cycle via plants, instead it will flow thro streams and rivers= takes longer to cycle thro
  • vegetation is crucial for areas conventional rainfall( essential for all rainforest life so severe deforestation = devastating knock on effects on rest of ecosystem)