GEOLOGY 101

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GEOLOGY 101

• Today Chapter 19
• A Hidden Reserve Groundwater

Course Website http//fouch101.asu.edu
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• Groundwater!

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Why bother?
GROUNDWATER

• Groundwater is
• drinking water for more 50 of all people
• 40 of irrigation water
• important for livestock industry
• an overused resource resulting in
• - water shortages
• - land subsidence
• - contamination

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Why bother?
GROUNDWATER

• Groundwater is
• typically misunderstood

Underground lakes and rivers are rare Most
underground water exists in spaces between
grains (in pore spaces)

• geological important erosional agent

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Porous Sandstone
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Fractured Shale
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Groundwater storage movement
GROUND- WATER
Important factors
porosity - percent of the volume of material that
is pore spaces sandstone porous shale less
porous permeability - the ability of a material
to transmit a fluid sandstone permeable
shale - impermeable
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Wells

• Wells can supply water - if they intersect the
  water table.
• Pumping a well at a rate faster than water can
  flow in the aquifer creates a cone of depression.

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Groundwater Contamination
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GROUNDWATER
Problems and contamination

• Saltwater contamination (coastal areas)

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GROUNDWATER
Problems and contamination

• Land subsidence
• The removal of water allows the aquifer sediments
  to compact.
• Once compacted, the overlying unsaturated zone
  sediments will also drop in elevation.

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GROUNDWATER
Problems and contamination

• Subsidence (from pumping out water faster than
  replenishing)

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GROUNDWATER
Problems and contamination

• Subsidence (from pumping out water faster than
  replenishing)

Venice, Italy
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GROUNDWATER
Problems and contamination

• Groundwater contamination (due to human causes)

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GROUNDWATER
Problems and contamination

• Groundwater contamination (due to human causes)

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GROUNDWATER
Problems and contamination

• Groundwater contamination (due to human causes)

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Geologic alterations
GROUNDWATER

• caverns
• karst topography
• sink holes

Limestone, usually formed just below water table
Bedrock shaped (dissolved) by groundwater
Either gradual or abrupt depression in surface
due to dissolved limestone bedrock.
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Geologic alterations
GROUNDWATER

• caverns
• karst topography
• sink holes

Limestone, usually formed just below water table
Bedrock shaped (dissolved) by groundwater
Either gradual or abrupt depression in surface
due to dissolved limestone bedrock.
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Geologic alterations
GROUNDWATER

• caverns
• karst topography
• sink holes

Limestone, usually formed just below water table
Bedrock shaped (dissolved) by groundwater
Either gradual or abrupt depression in surface
due to dissolved limestone bedrock.
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Geologic alterations
GROUNDWATER

• caverns
• karst topography
• sink holes

Limestone, usually formed just below water table
Arecibo Radio-telescope, Puerto Rico
Bedrock shaped (dissolved) by groundwater
Either gradual or abrupt depression in surface
due to dissolved limestone bedrock.
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Geologic alterations
GROUNDWATER

• caverns
• karst topography
• sink holes

Limestone, usually formed just below water table
Bedrock shaped (dissolved) by groundwater
Either gradual or abrupt depression in surface
due to dissolved limestone bedrock.
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Geologic alterations
GROUNDWATER

• caverns
• karst topography
• sink holes

Limestone, usually formed just below water table
Bedrock shaped (dissolved) by groundwater
Either gradual or abrupt depression in surface
due to dissolved limestone bedrock.
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Geologic alterations
GROUNDWATER

• caverns
• karst topography
• sink holes

Limestone, usually formed just below water table
Bedrock shaped (dissolved) by groundwater
Either gradual or abrupt depression in surface
due to dissolved limestone bedrock.
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Groundwater recharge and discharge takes time

• The rate of movement of groundwater depends on
  many factors including the flowpath.

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Springs, hot springs, geysers
GROUNDWATER
Spring
Outflow of ground water from water table
intersecting Earths surface
Marble Canyon AZ
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Springs, hot springs, geysers
GROUNDWATER
Springs
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Springs, hot springs, geysers
GROUNDWATER
Desert Oases
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Springs, hot springs, geysers
GROUNDWATER
Spring w/ water 6-9oC (10-15o F) warmer than mean
annual air temperature
Hot springs
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Springs, hot springs, geysers
GROUNDWATER
Geysers
Intermittent hot fountains/columns of water
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Springs, hot springs, geysers
GROUNDWATER
Geysers
Intermittent hot fountains/columns of water
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