the water cycle - global distribution and stores

what percentage of water is salt water

97.5%

what percentage of water is freshwater

2.5%

of the 2.5% of freshwater what percentage is glaciers and icecaps and how much is groundwater

68.6% glaciers, 30.1% groundwater

what percentage of water is stored in the hydrosphere

96.5% of earth’s water stored as saline water in the ocean

what percentage of earth’s surface is covered by earth’s surface

72%

how can the ocean remain liquid in temperature’s below 0C

salt

how much has the pH of the ocean fallen

8.25 to 8.14 in last 250 years due to increased atmospheric carbon

what is terrestrial water

surface water - rivers

biological water - water stored in biomass

varies considerably around the world e.g. rainforests store more water than deserts

what are the two different water stores in the lithosphere

groundwater, soil

what percentage of groundwater is stored in rocks underground (aquifers)

30.1%

in what rock type are aquifers commonly found

porous and permeable rock e.g. chalk

exploitation of aquifers

many exploited by agricultural industry for unsustainable irrigation - increases risk of them turning into saline aquifers as sea water can infiltrate into the rocks

lithosphere soil storage

capacity of soil water storage can vary (soil water budget). porous, sandy soils hold little water but allow water transfer. clay soils store large amounts of water but allow little transfer through

what is the water table

upper layer of saturated rock

how can the water table change

groundwater flow and water abstraction

water abstraction

groundwater pumped out for drinking water or industry

how can agriculture cause the water table to rise

irrigation of crops as excess water seeps into the ground

what happens if water isn’t extracted in a sustainable way

water table can drop permanently

when does groundwater depletion occur

when rate of groundwater extraction through wells is greater than the rate of replenishment from precipitation.

5 locations of Cryospheric water store

sea ice

permafrost

ice caps

ice sheets

alpine glacier

outline sea ice ad a cryospheric water store

e.g. the arctic ocean - sea ice doesn’t raise sea levels when it melts as it forms from ocean water. Ice shelves form when ice sheets and glaciers move out over oceans e.g. Antarctica and Greenland. Icebergs break off and only raise sea levels when they first leave land and go into the water, not when they melt.

permafrost

e.g. frozen ground in Alaska - ground that remains at or below 0C for at least two consecutive years. thickness varies. Melting permafrost releases huge amounts of carbon dioxide and methane

ice caps

dome shaped and located over the highest points of an upland areas

Ice sheets e.g. Greenland

an ice sheet is a mass of glacial land ice exceeding 50,000km²

Ice is a large store of water