Global hydrological cycle

• global hydrological cycle = fixed amount of water on earth(closed system) bc water cannot enter or leave earth or atmosphere, composed of 3 things; stores, flows and processes
• global stores

  • inc all water eg water vapour, ice, saline or freshwater
  • oceans
  • lakes
  • aquifers (underground lakes)
  • cryosphere (glaciers and ice sheets)
• local stores

  • vegetation storage
  • surface storage
  • soil moisture
  • groundwater storage
• flows = how water moves from one state to another

  • infiltration
  • throughflow
  • percolation
  • stem flow
  • base flow
  • channel flow
  • surface runoff
• processes = what drives the flows between stores

  • precipitation
  • evaporation
  • transpiration
  • cryosphere (glaciers and ice sheets) exchanges
  • runoff
• size of water stores

  • total global water supply; 96.5% oceans and seas, 2.5% freshwater and 0.9% saline
  • 2.5% freshwater-> 68.8% cryosphere, 30% groundwater and 1.2% surface water
  • 1.2% surface water-> 69% ground ice and permafrost, 20% lakes, 3.8% soil moisture, 3% atmosphere, 2.6% swamps + marshes, 0.5% rivers and 0.26% biosphere
• Global water supply= split between many diff stores

  • 96.5% oceans and seas
  • 2.5% freshwater eg lakes
  • 0.9% other saline water sources