Unit 7 Day 6
Groundwater
VA SOL
SOL 9 The student will investigate and understand
how freshwater resources are influenced by geological
processes and the activities of humans. Key concepts
include
b. development of
topography
c. identification of groundwater zones including the
water table,
, and zone of
;
e. dependence on freshwater resources and the
effects of human usage on water quality;
The

contained by landmasses is mostly
of that fresh water is locked in ice caps and
Objective
1.
Interpret a simple groundwater diagram showing
the zone of aeration, the zone of saturation, the water
table, and an
.
2. Describe underground water sources (such as
aquifers and
).
3. Explain the development of karst topography to
include key terminology: joint, cavern,
, carbonation, stalactite, and stalagmite.
4. Locate the region of karst topography in Virginia
as the Valley & Ridge Province where
/dolomite is common.
Most of the remaining fresh water is stored
.
Ground Water
If you drill a hole deep enough an
.
you will find water. Even in the
! Groundwater is present everywhere, but is only a
small fraction of the Earth’s water supply.
Groundwater Movement and Storage
As the Water Cycle runs much of the precipitation
that falls on land becomes groundwater. From there it
will begin a journey back to the ocean again.

is the process by which
precipitation enters the ground and
The Hydrosphere

is the water on and in Earth’s crust.

in a material

.
of the hydrosphere in contained in the
is the percentage of
25
Well-sorted sand has a porosity of about 30%

is the ability of a material to

are natural underground
openings that connect to the surface and are formed
when groundwater dissolves limestone
through it and
depends on how well connected the pores are
Sandstone, limestone and well-fractured bedrock is
very permeable

are

is the depth at which
groundwater completely
of a material

is the
of the zone of saturation

are dripstone formations that
form slowly on the top of caves as water drips slowly
leaving a tiny deposit of CaCO3 that accumulates over
time


is a
through which groundwater
flows
Aquiclude is an impermeable barrier to groundwater
are mound-shaped
dripstone deposits that form underneath the stalactites.
Dripstone columns are formed when stalactites and
stalagmites grow together
Karst Topography
Limestone
regions that have
,
sinks, and sinking streams are said to have
topography named after a limestone region in Croatia
where these features are especially well-developed.
About 10% of the Earths surface and 15% of the
United States is this type

is a depression in the ground
caused by the collapse of a cave
Sinkholes are common in Florida, and Texas
flow
Virginia has an extensive cave system that extends
Groundwater Erosion
Most
groundwater contains
that forms when carbon dioxide dissolves in water and
combines in water molecules. The
attacks certain
rocks
Carbonate rocks such as limestone that consist
mostly of CaCO3 are susceptible to acid dissolution
through the
that can be visited and explored quite easily
Ground Water Systems
Ground Water Systems
Groundwater moves slowly but continuously through
on its journey back to the oceans.
The average length of time that groundwater remains
underground is
.

have water temperatures
higher than the human body and are common in the
western United States where the subsurface is still hot
from recent

Groundwater can return to the surface at places where
the
Earth’s surface
are
that erupt at regular intervals

, located in Yellowstone National
Park in Wyoming is a famous geyser
http://www.nps.gov/yell/photosmultimedia/yellowston
elive.htm
Wells
Many homes in Norfolk use well water for lawns,
utility, and even drinking water
Well is a hole dug or drilled into the ground to reach a

emerge where an aquifer and
Aquiclude come in contact at the surface

and sandstone
, sand and gravel are common aquifers
of groundwater
Simple wells are dug below the water table into the

is a
lowering of the water table around the head of a well

is the difference between the
original water table level and the level in the pumped
well
Clay and shale layers are Aquiclude
Many of the lakes in
such as
Florida are flooded sinkholes that are fed by
.
27

is when precipitation and
runoff is added back to the zone of saturation
In coastal areas such as Norfolk
If recharge does not keep pace with drawdown the
wells in an area will go
Confined Aquifers
Water table aquifers are unprotected and
. Confined aquifers are
sandwiched between aquicludes that form barriers that
prevent pollutants from reaching the ground water

contain water
between two aquicludes
the freshwater supplies and makes well
water undrinkable
It is also believed that a
near the mouth of the Chesapeake Bay 35 million years
ago contaminated the aquifer by
in the seawater into the parent
bedrock
Industrial and harmful chemical wastes from
The
is caused by the recharge
areas being at a higher elevation
Water Quality
Earth’s most precious
. Because of its natural filtering
and availability groundwater is the main source of this
vital need.
Many geologic processes such as erosion can have
harmful effects on our freshwater supplies

improperly constructed or maintained dumpsites (or
) can contaminate
groundwater for many miles around the source

in solution
by the fine-grained sediments
It is important to realize that protecting our water
supply is of vital importance.
It is our responsibility to be aware of how human

is the sinking of land
elevation when too much groundwater is removed
activities affect our resources and act (and vote)
accordingly!