complete solution
Hydrologic Cycle
Water evaporates from moist surfaces, falls as rain or snow, passes through living
organisms and returns to the oceans.
How much water evaporates each year from the world's oceans?
500,000km
Three principal factors controlling global water deficits and surpluses:
Global atmospheric circulation, proximity to water sources, and topography.
Rain Shadow Effect
Cool, dry air descends from the mountaintop down the other side of the mountain
(leeward side) creating dry areas with very little precipitation.
How much liquid water do the oceans hold?
97%
Oceans role:
Play major role in moderating earth's climate. The currents moderate climate by
redistributing warm and cold water around the earth.
How much of the world's water is classified as fresh?
2.4%
Groundwater
Second largest reservoir of fresh water.
Infiltration
Process of water percolating through the soil and into fractures and permeable rocks.
Zone of aeration
Upper soil layers that hold both air and water.
Zone of saturation
Lower soil layers where all spaces are filled with water.
Water table
Top of zone of saturation.
Aquifers
Porous layers of sand, gravel, or rock lying below the water table.
Artesian
Pressurized aquifer intersects the surface (water flows without pumping).
Recharge zones
Areas where water infiltrates into an aquifer.
Smallest water reservoirs
Contains < 0.001% of total water supply.
How many gallons per person per year needed to meet needs (According to UN)?
264,172 gallons
Water Stress
Occurs when human and ecosystem needs exceed the renewable water supplies,
resulting in competition.
Withdrawal
Total amount of water removed from a water body.