1.1.2 Global Scale Flashcards
Spheres involved
hydrosphere (l), lithosphere, cryosphere (s), atmosphere (g)
Ocean percentage
97%
Freshwater stores
glaciers, ice caps & ice sheets - 69%
groundwater - 30%
Surface (permafrost, lakes, swamps, rivers, living organisms) - 1%
Aquifers definition
Underground water stores below water table (unevenly distributed around globe)
Types of aquifer
Confined (trapped between two layers of rock) & unconfined (can receive water from surfaces)
Shallow groundwater aquifers store water for…
200yrs
Deep fossil aquifers…
formed during wetter climatic periods, last 10,000 yrs
Glaciers store water for…
20-100 yrs (from accumulation to ablation/calving)
Lakes store water for…
50-100 yrs
Seasonal snow & rivers store water for…
2-6 mnths
Soil water stored for…
1-2 mnths
Water table
boundary between water-saturated ground and unsaturated ground.
Zones above and below water table
Above = vadose zone Below = Phreatic zone
The water table usually follows…
the topography of the ground
If the water table intersects with the land surface…
it causes a spring or oasis
If the water table is higher than the ground…
a swamp is caused
Impervious surfaces (e.g. from urbanisation) …
prevent infiltration to the phreatic zone causing a dip in the water table
Water tables are useful for researchers…
to measure the health of aquifers
Aquifer depletion is caused by…
overabstraction by industry, agriculture and private use.
Some oceanic islands…
have tidal tables. The freshwater is less dense than the salt water so stays above it.
