5.1 importance of Global Hydrological Cycle Flashcards
what is the global hydrological cycle?
circulation of water around the earth
how does the ghc operate?
operates as a CLOSED system (no external inputs/ outputs): total volume of water on the earth is constant and fixed!!!!
a balance of inputs and outputs: water is moved between stores by flows/ transfers/ fluxes
what drives the cycle?
power that drives the cycle comes from 2 sources: solar energy (in the form of heat)
GPE (causes rivers to flow downhill and precipitation to fall to the ground: keeps water flowing through the system!)
what are the 4 main stores?
stores within the cycle is where water is held. the 4 main ones:
1. oceans (96.5%)
2. glaciers and ice caps (cyrosphere)
3. surface run off ( umbrella term for land based stores incl. rivers, lakes and groundwater)
4. the atmosphere
what are flows and fluxes? and examples?
transfer of water from one store to another.
flows include|; percolation, infiltration, through flow, groundwater flow and surface run off
- the GREATEST flux is EVAPORATION from ocean to the atmosphere (4130km3 a year!)
- SECOND is PRECIPITATION from atmosphere to the ocean (3730km3 a year)
- third is precipitation from atmosphere onto land ( 1130km3)
- fourth is evaporation from land to atmosphere (730km3)
smallest flux is surface runoff between land and oceans
1c) freshwater stores
oceans are a store for 96.5% of the worlds water
freshwater only accounts for 2.5%!!!
of this 2.5%,
69% is cyrosphere
30% is groundwater
less than 1% is stored in the biosphere
residency times
(def: the average amount of time a water molecule will stay in a store)
LONGEST= ice caps/ glaciers/ permafrosts (1000- 10000 yrs)
groundwater (2wks- 10000 yrs)
oceans/ seas (4000 yrs)
lakes/ reservoirs (10 yrs)
swamps (1-10 yrs)
river channels (2wks)
atmospheric water (10 days)
SHORTEST= biospheric water (7 days)
