Introduction
Groundwater Hydraulics
Daene C. McKinney
Course Objectives
• Introduction to groundwater, including:
– Groundwater in the hydrologic cycle
– Characteristics of porous media
– Darcy's law of flow in porous media
– Continuity principles
– Well hydraulics and aquifer testing
– Applications of groundwater hydraulics
– Characteristics of unsaturated flow
Housekeeping
• Prerequisites: CE 356 Hydraulics
• Text:
– Groundwater Hydrology, Todd, David Keith, Larry W. Mays, John Wiley
& Sons, 2004
• Homework:
– Due dates on web site
– Excessively late (> 2 days) penalized 50% per day late
– Expectations:
• Clear presentation,
• No computational errors, Answers clearly marked, Units marked and used
correctly
• Software:
– GroundwaterVistas (graphical interface for USGS MODFLOW)
– Available on CAEE Virtual Workspace
Housekeeping (Cont.)
 Grading:
 Exams (2):
34%
 No makeups
 No Final
 Homework:
 Project:
32%
34%
Letter grades will be
assigned as follows:
A
92 – 100%
A89 – 91%
B+
86 – 88%
B
82 – 85%
B79 – 81%
C+
76 – 78%
C
70 – 75%
C67 – 69%
D+
64 – 66%
D
58 – 63%
D55 – 58%
F
< 55%
Projects
•
•
•
Work in a team on a design project dealing with limiting
hydraulic containment of a contaminated aquifer
Real, complex groundwater issue
Each team
–
–
–
•
Make a video presentation of their results
Deliver the final video (the presentation, model and results)
Critique other teams’ videos
Purposes of the project:
–
–
Enable you to explore in-depth an aspect of groundwater
Provide experience formulating, executing and presenting a
groundwater investigation
Groundwater and Aquifers
Groundwater Hydraulics
Daene C. McKinney
Some Terminology
• Hydrology ()
–  - “water”;  - “study of”
– Study of Water: properties, distribution, and
effects on the Earth’s surface, soil, and
atmosphere
• Water Management
– Sustainable use of water resources
– Manipulating the hydrologic cycle
• Hydraulic structures, water supply, water treatment, wastewater
treatment & disposal, irrigation, hydropower generation, flood
control, etc.
Some History
• Qanats
– Subterranean tunnels used to tap and
transport groundwater
– Originally in Persia
– Kilometers in length
– Up to 3000 years old
– Many still operating
Ancient Persian Qanat
• Chinese Salt Wells
–
–
–
–
–
1000 years ago: Drilled wells
Over 300 meters deep
Bamboo to retrieve cuttings
By year 1858: 1000 meters deep
Called “cable tool” drilling today
Ancient Chinese Salt Well
Old Theories
 Homer (~1000 BC)
 “from whom all rivers are and the
entire sea and all springs and all deep
wells have their waters”
 Seneca (3 BC -65 AD)
 “You may be quite sure that it not mere
rainwater that is carried down into our
greatest rivers.”
 Da Vinci (1452-1519)
 accurate representation of the
hydrologic cycle
 Descartes (1596-1650)
 Vapors are drawn up from the earth
and condensed…
 Kircher (1615-1680)
 Water from the ocean is vaporized by
the hot earth, rises, and condenses
inside mountains.
Old Theories (Cont.)
• Vitruvius (~80-20 BC)
– 8th Book on Water and Aqueducts.
Rain and snow on land reappears as
springs and rivers
• Palissy (1509-1590).
– French scientist and potter - accurate
representation of the hydrologic cycle
• Perrault (1670):
– Water balance on the Seine. River
flow explained by rainfall.
• Mariotte (1620-1684).
– French physicist. First recharge
estimates. Leaky roof analogy.
• Vallisnieri (1723)
– At lower altitudes in the Alps, artesian
wells are common. Higher altitudes in
Alps, streams are losing water
Groundwater originates from rain.
Modern Theories
• Henri Darcy (1856)
– Relationship for the flow through
sand filters. Resistance of flow
through aquifers. Solution for
unsteady flow.
• King (1899)
– Water table maps, groundwater
flow, cross-section
Henri Darcy
• Hazen, Slichter, O. E. Meinzer
(1900s)
– Practical applications, basing on
theoretical principles of French
hydrogeology
• C.V. Theis (1930s)
– Well Hydraulics
C.V. Theis
Global Water Resources
TOTAL GLOBAL (Water)
2.5% OF TOTAL GLOBAL
(Freshwater)
68.9% Glaciers & Permanent
Snow Cover
97.5%
Salt
Water
29.9% Fresh
Ground water
0.3% Freshwater Lakes &
River Storage. Only this
portion is renewable
Groundwater Management in IWRM: Training Manual, GW-MATE, 2010
0.9% Other including
soil moisture, swamp
water and permafrost
Global Water Cycle
Residence time:
Average travel
time for water
through a
subsystem of the
hydrologic cycle
Tr = S/Q
Storage/flowrate
Principal sources of
fresh water for
human activities
(44,800 km3/yr)
Hydrologic Cycle (Local view)
Atmospheric Moisture
Rain
Snow
Evaporation
Interception
Throughfall and
Stem Flow
Snowpack
Snowmelt
Pervious
Our focus
Watershed
Boundary
Surface Impervious
Infiltration
Soil Moisture
Percolation
Evapotranspiration
Overland
Flow
Groundwater
Groundwater Flow
Streams and Lakes
Channel Flow
Runoff
Evaporation
Water Budgets
1.
Surface water budget
P + Qin – Qout + Qg – Es – Ts – I = DSs
2.
Groundwater budget
I + Gin – Gout - Qg – Eg – Tg = DSg
• System budget (1 + 2)
P - Q – E – T = DS
• If Ts = 0
G = DS - P + E - Qin + Qout
Major Aquifers of Texas
Ogallala
Edwards
Edwards Aquifer
•
Primary geologic unit is
Edwards Limestone
•
One of the most
permeable and
productive aquifers in
the U.S.
•
The aquifer occurs in 3
distinct segments:
•
Contributing zone
•
Recharge zone
•
Artesian zone
Formation of Edwards Aquifer
Contributing Zone of Edwards Aquifer
• Located north and west of
the aquifer in the region
referred to as the Edwards
Plateau or Texas Hill Country
• Largest part of the aquifer
spanning 4400 sq. miles
• Water in this region travels
to recharge zone
Recharge Zone of Edwards Aquifer
• Geologically known as the
Balcones fault zone
• It consists of an abundance of
Edwards Limestone that is
exposed at the surface
-provides path for water to
reach the artesian zone
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
The Edwards Group
Flowpaths of the Edwards Aquifer
The Ogallala Aquifer
• Approximately 170,000 wells draw
water from the aquifer.
•Water level declines of 2-3 feet
per year in some regions .
•Only 10% is restored by rainfall.
Example Ogallala Well Hydrograph
The Ogallala Aquifer
Water Level Change up to 1980
Water Level Change 1980 - 1994
Summary
• Course Introduction and Housekeeping
• Groundwater and Aqufiers
– Terminology
– History
• Global Water Resources
– Global Water Cycle
• Texas Aquifers
– Edwards
– Ogallala