Transcript Document

GROUNDWATER HYDROLOGY AND CONTAMINANT
TRANSPORT
CEVE 518
P.C. de Blanc
C.J. Newell
1. Hydrologic Cycle and Water
Distribution
2. Soil Horizons
3. Aquifers
4. Soil Texture
5. Porosity and Density
6. Saturation and Water Content
7. Hydraulic Head
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1. Hydrologic Cycle and Water
Distribution
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Hydrogeology: What is it?
• Hydrologic cycle – circulation of water in the
environment
• Hydrogeology examines the relationships of
geologic materials and flowing water
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Global Hydrologic Cycle
Domenico and Schwartz, 1990.
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Basin Hydrologic Cycle
Charbeneau, 2000.
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Basin Hydrologic Cycle – GW/SW Interaction
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Artesian Zone of Edwards
Aquifer
• The artesian zone is a
complex system of
interconnected voids
varying from microscopic
pores to open caverns
• Located between two
relatively less permeable
layers that confine and
pressurize the system
• Underlies 2100 square
miles of land
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Global Hydrologic Cycle – Schematic
Domenico and Schwartz, 1990.
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Basin Hydrologic Cycle – Schematic
Domenico and Schwartz, 1990.
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Basin Hydrologic Cycle – Quantitative Representation
Basin
Surface/
Soil
I
Aquifer
Domenico and Schwartz, 1990.
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2. Soil Horizons
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Charbeneau, 2000.
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Figure 15.1
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3. Aquifers
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Aquifers
Definition: A geological unit which can store and
supply significant quantities of water.
Principal aquifers by rock type:
Unconsolidated
Sandstone
Sandstone and Carbonate
Semiconsolidated
Carbonate-rock
Volcanic
Other rocks
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Occurrence of Ground
Water
• Ground water occurs
when water recharges
the subsurface through
cracks and pores in soil
and rock
• Shallow water level is
called the water table
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Recharge
Natural
• Precipitation
• Melting snow
• Infiltration by streams
and lakes
Artificial
• Recharge wells
• Water spread over land
in pits, furrows, ditches
• Small dams in stream
channels to detain and
deflect water
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Example Layered Aquifer System
Bedient et al., 1999.
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Other Aquifer Features
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Leaky and Perched Aquifers
• Leaky confined aquifer: represents a stratum that
allows water to flow from above through a leaky
confining zone into the underlying aquifer
• Perched aquifer: occurs when an unconfined water
zone sits on top of a clay lens, separated from the
main aquifer below
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4. Soil Texture
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Bedient et al., 1999.
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Particle Size Distribution
Poorly sorted
silty fine to
medium sand
Well sorted fine sand
Bedient et al., 1999.
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Particle Size Distribution
Charbeneau, 2000.
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4. Porosity and Density
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REV – Representative Elementary Volume
Charbeneau, 2000.
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REV – Scale Effect
Freeze and Cherry, 1979.
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Types of Porous Media
Freeze and Cherry, 1979.
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Typical Values of Porosity
Bedient et al., 1999.,
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6. Saturation and Water Content
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Soil Moisture Held by Capillary Pressure
Charbeneau, 2000.
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Moisture Content in Capillary Zone
Charbeneau, 2000.
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7. Hydraulic Head
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Pressure and Elevation Heads - Laboratory
 = pressure head
z = elevation head
h = total head
Freeze and Cherry, 1979.
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Pressure and Elevation Heads - Field
 = pressure head
z = elevation head
h = total head
Freeze and Cherry, 1979.
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Two Confined Aquifers with Different Heads
Groundwater will tend to
flow from the top aquifer
to the bottom aquifer.
We can’t make any
conclusion about
horizontal head gradients
from this picture.
Charbeneau, 2000.
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Horizontal and Vertical Head Gradients
Freeze and Cherry, 1979.
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Horizontal and Vertical Head Gradients
Freeze and Cherry, 1979.
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Lecture 2
Reading Assignments
1.
2.
3.
4.
Hydrologic Cycle and Water Distribution

Bedient et al., pp. 1-6

Domenico & Schwartz, pp. 9-21
Soil Horizons

Bedient et al., pp. 15-18

Charbeneau, pp. 5-6
Aquifers/Soil Texture/Porosity and Density/Saturation and Water Content

Bedient et al., pp. 18-23

Charbeneau, pp. 2-12
Hydraulic Head

Bedient et al., pg. 24

Domenico and Schwartz, pp. 58-59

Freeze and Cherry, pp. 18-25
Note: Only reading in Bedient et al. is required. Other reading assignments are highly
recommended and contain extended explanations that might be helpful for your understanding of
the material.
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