Groundwater
14.1 Water in the Ground
14.2 Conserving Groundwater
14.3 Groundwater and Geology
Groundwater
Water in the Ground
VOCABULARY
groundwater
porosity
permeability
water table
The amount of water that rocks or soil can hold
depends on their porosity and permeability.
The water table is the top of the water-saturated
region of the ground. The depth of the water table
depends on climate, season, and location.
capillary action
ordinary well
Zone of aeration
spring
Capillary fringe
Zone of saturation
aquifer
artesian formation
geyser
Zone of
aeration
Zone of
saturation
Impermeable
layer
Water
table
Zone of saturation :
All the pores and cracks filled with water
Zone of aeration : Area above the water table mostly filled with air
How groundwater moves
• Groundwater usually travels slowly
underground seeping and filtering through
particles of soil and pores within rocks.
• Gravity is the prime factor in the movement
of groundwater from higher to lower locations
• The rock material can retard (impermeable
rock) and divert flow.
• As the groundwater flows, pollutants follow
the flow and spread out.
Groundwater
Water in the Ground
Groundwater reaches the surface through natural springs and
through wells. Aquifers are permeable layers of rock and sediment
that have groundwater in enough quantity to supply wells. In areas
associated with volcanic activity, groundwater may be very hot,
resulting in the formation of springs and geysers.
Groundwater: Water that enters and is stored in
the ground.
Porosity: The percent of a material’s volume that
is pore space.
Permeability: The rate at which water or other
liquids passes through the pore spaces of a rock.
Porosity: The percent of a material’s
volume that is pore space.
Permeability:
The rate at which
water or other
liquids passes
through the pore
spaces of a rock.
Groundwater: aquifers
• What would be the properties
(porosity/permeability) of conglomerate?
• High porosity, high permeability
Groundwater: aquifers
• What would be the properties (porosity/permeability) of
unfractured granite?
• Low porosity, low permeability
Water in the Ground
Water table: The surface below which the
ground is saturated with water.
Capillary action: A phenomenon whereby
groundwater rises because the water
molecules are attracted to soil particles.
Spring: A small stream of water whose source
is groundwater that has reached the surface.
Aquifer: A permeable layer of rock and
sediment that stores and carries groundwater
in enough quantities to supply wells.
Geyser: A hot spring that intermittently shoots
columns of hot water and steam into the air.
The Water Table
Spring:
A small stream
of water whose
source is
groundwater
that has
reached the
surface.
The Water Table
Spring:
A small
stream of
water
whose
source is
groundwat
er that has
reached
the
surface.
Artesian formation: An arrangement of a permeable
layer of rock sandwiched between two layers of
impermeable rock.
Artesian Well
Artesian
formation:
An
arrangement
of a
permeable
layer of rock
sandwiched
between two
layers of
impermeable
rock.
Geyser:
A hot spring
that
intermittently
shoots
columns of
hot water
and steam
into the air.
Formation of a Water Table
Groundwater
VOCABULARY
mineral deposit
cavern
karst topography
Groundwater and Geology
As water moves through the ground, it dissolves
minerals. When the groundwater cools or
evaporates, the dissolved minerals are often left
behind as deposits such as travertine, geyserite,
petrified wood, stalactites, stalagmites, and the
cement that binds sedimentary rocks.
Travertine is a calcite
deposit.
Groundwater
Groundwater and Geology
Groundwater containing carbonic acid dissolves
limestone, forming caverns and features of karst
topography.
1. Rainwater
containing
carbonic acid
seeps into the
ground.
2. Limestone
dissolves, forming
underground
caves.
3. Below the water
table, the cave is
filled with water.
Limestone
Cave
Formation
Groundwater and Geology
Mineral deposits: A deposit that is left behind when
groundwater that contains minerals cools or
evaporates.
Cavern: A large underground chamber.
Karst topography: Topography characterized by
sinkholes, sinkhole ponds, lost rivers, and
underground drainage; forms in areas with bedrock
made of calcite, dolomite, or other minerals that
dissolve easily.
Cavern:
A large
underground
chamber.
Karst
topography:
Topography
characterized by
sinkholes,
sinkhole ponds,
lost rivers, and
underground
drainage; forms in
areas with
bedrock made of
calcite, dolomite,
or other minerals
that dissolve
easily.
Mineral deposits: A deposit that is left behind
when groundwater that contains minerals cools or
evaporates.
Groundwater
VOCABULARY
water budget
recharge
surplus
usage
Conserving Groundwater
A water budget relates the recharge, surplus,
usage, and deficit of soil water to the moisture
needs and the moisture supply of an area.
Overuse of groundwater leads to problems such
as subsidence. Groundwater pollution is a
serious threat to supplies of usable water.
deficit
A worker sorting
hazardous waste for
safe disposal.
Conserving Groundwater
Water budget: Describes the income and the spending
of water in a region.
Recharge: The refilling of soil water supply at times
when plants need little moisture.
Surplus: The condition of having rainfall greater than
the need for moisture when the soil is already
saturated.
Usage: The condition where plants draw water from the
soil at times when the need for moisture is greater
than the rainfall.
Deficit: The condition in which stored soil water is gone
and the need for moisture is greater than the rainfall.
Usage:
The condition where
plants draw water
from the soil at times
when the need for
moisture is greater
than the rainfall.
Formation of a Cone of Depression
Pollution in Water
When pollutants enter the ground, they spread
out in the groundwater.
If there is no movement of the groundwater,
they disperse evenly in all directions.
• What happens when a new well here is
heavily pumped?
Flow
direction can
change