Transcript Groundwater a fresh water source

Groundwater
a Fresh water source
Essential Question:
What is the distribution of fresh
and salt water on Earth?
What is Groundwater?
 Water
located within rocks below earth’s
surface is called groundwater
 Groundwater fills the open spaces in
rocks, sediment, and soil beneath the
surface
 Groundwater is an important source for
domestic, industrial, and agricultural
use, but is also an important role in
erosion and as an energy source in some
areas
Ground Water and the Water
Cycle
 Groundwater
is
about 22% of the
world’s fresh water


comes from
precipitation,
percolating through
soils and sediment
streams, lakes, and
snowmelt also
contribute
How Does Groundwater Move?
 Gravity
moves groundwater, just as it does
water in channels
 Moves from areas of high pressure to areas
of low pressure
 May move up to 250 m per day, or less than
a few cm/day
The Water Table
 Zone

pore spaces contain mostly air
 Zone

of aeration
of saturation
pore spaces contain mostly water
 Water

table
the top of the zone of saturation
Water Table
Zone of aeration
Saturated Zone
Groundwater
What Properties of Earth’s
Materials Allow Them to Absorb
Water?
 Aquifer

A rock layer that stores
ground water and allows
the flow of groundwater
 Porosity

The percentage of open
space between individual
rock particles
 Permeability

A rocks ability to let
water pass through
What are Springs?
 Groundwater
movement is determined by the
slope of the water table
 Groundwater tends to move down slope
 If the water table reaches Earth’s surface, water
will flow out from the ground and form a spring
 Springs are an important source of drinking water
and can form lakes
What Are Water Wells?
A
human-made
hole that is
deeper than the
level of the water
table is called a
well
 If
a well is not
deep enough it
can dry up
What Are Artesian Systems?

A sloping layer of permeable rock sandwiched
between two layers of impermeable rock is called an
artesian formation
 An artesian spring is a spring whose water flows from
a crack in the cap rock or top impermeable layer
 Often found in deserts where they are the only source
of water
Groundwater Contamination
 Most

common sources:
sewage, landfills, toxic waste disposal sites, and
agriculture
 practices
by industry and citizens
Groundwater and Erosion
 Groundwater
causes erosion by dissolving rock
 This erosion can form caves and sinkholes
 When the water table is lower than the level of
the cave, the cave is no longer supported by the
water underneath causing it to collapse