chapter 3 part 2 Flashcards
1
Q
Tests on Illinois water gave ages of
A
50 to more than 100 years
2
Q
Tests on Illinois water gave ages of 50 to more than 100 years. (Beyond 100 years, the tritium concentrations …………………………..)
A
could not be measured accurately
3
Q
Tests on Illinois water gave ages of 50 to more than 100 years. (Beyond 100 years, the tritium concentrations could not be measured accurately.) These ages are generally in keeping with the …………………… when all the ……………………… in each area are considered
A
anticipated values
hydrologic factors
4
Q
water must travel through …………………….. before becoming groundwater
A
various strata
5
Q
water must travel through various strata before becoming groundwater. Below the surface it
A
moves first through the subsoil (the belt of soil water)
6
Q
water must travel through various strata before becoming groundwater. Below the surface it moves first through the subsoil (the belt of soil water), ……………………………. , the ………………………… and finally into …………………
A
the intermediate layer,
the capillary fringe
and finally into the groundwater bed.
7
Q
A
A
8
Q
B
A
9
Q
C
A
10
Q
D
A
11
Q
E
A
12
Q
F
A
13
Q
G
A
14
Q
H
A
15
Q
I
A
16
Q
J
A
17
Q
water must travel through various strata before becoming groundwater. Below the surface it moves first through the subsoil (the belt of soil water), the intermediate layer, the capillary fringe and finally into the groundwater bed.
These layers vary
A
in depth and are not too sharply defined
18
Q
These layers vary in depth and are not too sharply defined. In fact, there is a ……………………. from one to another
A
gradual transition
19
Q
These layers vary in depth and are not too sharply defined. In fact, there is a gradual transition from one to another until
A
the ground water level or zone of saturation is reached
20
Q
These layers vary in depth and are not too sharply defined. In fact, there is a gradual transition from one to another until the ground water level or zone of saturation is reached
Even after water moves into the ………………………….. much of it may still return to the …………………..
A
topsoil and subsoil
atmosphere
21
Q
Even after water moves into the topsoil and subsoil, much of it may still return to the atmosphere either through
A
evaporation or transpiration
22
Q
Even after water moves into the topsoil and subsoil, much of it may still return to the atmosphere either through evaporation or transpiration. Water is held in the subsoil by
A
molecular attraction
23
Q
Water is held in the subsoil by molecular attraction. It is only after
A
sufficient water has accumulated here that it begins to seep downward under the pull of gravity
24
Q
It is only after sufficient water has accumulated here that it begins to seep downward under the pull of gravity. The subsoil may extend down
A
50 feet
25
It is only after sufficient water has accumulated here that it begins to seep downward under the pull of gravity. The subsoil may extend down 50 feet. It supplies the water needed for
the growth of vegetation
26
It is only after sufficient water has accumulated here that it begins to seep downward under the pull of gravity. The subsoil may extend down 50 feet. It supplies the water needed for the growth of vegetation. Consequently, it is extremely important to
farmers
27
Water in the intermediate belt is generally considered in
"dead storage."
28
Water in the intermediate belt is generally considered in "dead storage." To all intents and purposes it is
suspended and does not flow into wells
29
Water in the intermediate belt is generally considered in "dead storage." To all intents and purposes it is suspended and does not flow into wells. This belt varies from a
hairsbreadth to several hundred feet.
30
Below lies the capillary fringe. The thickness of this capillary fringe depends on its
composition
31
Below lies the capillary fringe. The thickness of this capillary fringe depends on its composition. In silty materials it may extend down for
several feet
32
Below lies the capillary fringe. The thickness of this capillary fringe depends on its composition. In silty materials it may extend down for several feet. In coarse, gravelly materials it may go down
less than an inch
33
Below lies the capillary fringe. The thickness of this capillary fringe depends on its composition. In silty materials it may extend down for several feet. In coarse, gravelly materials it may go down less than an inch. Even in this capillary fringe, water will
still not enter well systems
34
Below lies the capillary fringe. The thickness of this capillary fringe depends on its composition. In silty materials it may extend down for several feet. In coarse, gravelly materials it may go down less than an inch. Even in this capillary fringe, water will still not enter well systems. It is only when it reaches the ................................... that it may be .........................
zone of saturation
drawn back up to the surface by wells
35
Capillary action, where water
touches a solid
36
Capillary action, where water touches a solid, capillary action causes the water at that point to
rise higher than that portion of its surface not in contact with the solid
37
Capillary action is due to
adhesion, cohesion and surface tension
38
Capillary action is due to adhesion, cohesion and surface tension. Capillarity is one of the causes of water's
rising in the sail as in the capillary fringe
39
This zone of saturation forms a huge
natural reservoir
40
This zone of saturation forms a huge natural reservoir that feeds
springs and streams in addition to our wells.
41
This zone of saturation forms a huge natural reservoir that feeds springs and streams in addition to our wells. Its thickness varies from
two to hundreds of feet
42
This zone of saturation forms a huge natural reservoir that feeds springs and streams in addition to our wells. Its thickness varies from two to hundreds of feet, depending on
local geologic conditions
43
In general, the contours of the water table parallel
the surface contours
44
In general, the contours of the water table parallel the surface contours. However, the water table goes deeper
under high elevations and rises nearer to the surface under lower elevations
45
At ....................................., the surface and water table elevations coincide
springs and flowing streams
46
Groundwater is abstracted from
beneath the earth’s surface
47
Groundwater is abstracted from beneath the earth’s surface using methods similar to the
oil industry
48
Wells are drilled into
aquifers and pumps
49
Wells are drilled into aquifers and pumps are used to bring
groundwater to the surface
50
In some cases groundwater may naturally flow
out of a well
51
In some cases groundwater may naturally flow out of a well, which is known as
artesian flow
52
The existence of artesian flow is not necessarily an indication of
high well or aquifer yield
53
The existence of artesian flow is not necessarily an indication of high well or aquifer yield.
It is a physical phenomenon reflecting ...................
aquifer conditions
54
It is a physical phenomenon reflecting aquifer conditions whereby groundwater is
trapped below an impermeable layer
55
It is a physical phenomenon reflecting aquifer conditions whereby groundwater is trapped below an impermeable layer, in conjunction with
recharge at a higher level
56
It is a physical phenomenon reflecting aquifer conditions whereby groundwater is trapped below an impermeable layer, in conjunction with recharge at a higher level. Alternatively it can be caused when
groundwater intercepts very impermeable material or a boundary
57
It is a physical phenomenon reflecting aquifer conditions whereby groundwater is trapped below an impermeable layer, in conjunction with recharge at a higher level. Alternatively it can be caused when groundwater intercepts very impermeable material or a boundary, forcing flow to
the surface
58
The first challenge for someone looking to use groundwater is to
locate a viable source
59
The first challenge for someone looking to use groundwater is to locate a viable source, particularly if
large quantities are required such as for crop irrigation
60
The first challenge for someone looking to use groundwater is to locate a viable source, particularly if large quantities are required such as for crop irrigation. Domestic supplies are more widely available because
only smaller volumes are needed
61
Domestic supplies are more widely available because only smaller volumes are needed, which can often be
pumped at low rates to storage tanks
62
The subsurface mapping of geological formations and the location of old stream channels can help
build a picture of how an area has been formed and where groundwater may be found
63
.......................................................... and ............................................... can help build a picture of how an area has been formed and where groundwater may be found
The subsurface mapping of geological formations and the location of old stream channels
64
The most frequently used and reliable descriptor of underground strata and groundwater are
drilling contractor’s records commonly referred to as well logs
65
The most frequently used and reliable descriptor of underground strata and groundwater are drilling contractor’s records commonly referred to as well logs. Well logs describe the
material that was encountered during drilling
66
The most frequently used and reliable descriptor of underground strata and groundwater are drilling contractor’s records commonly referred to as well logs. Well logs describe the material that was encountered during drilling and general details such as
yield information and physical dimensions
67
The most frequently used and reliable descriptor of underground strata and groundwater are drilling contractor’s records commonly referred to as well logs. Well logs describe the material that was encountered during drilling and general details such as yield information and physical dimensions. The well logs also show
the results of the test pump
68
Locating groundwater is a
science and an art
69
Locating groundwater is a science and an art. It requires a basic knowledge of ......................., as well as, ........................... and ...................
hydrogeology, as well as, observation and inquiry
70
As mentioned early, groundwater flows from
a recharge area to a discharge point
71
As mentioned early, groundwater flows from a recharge area to a discharge point. Generally, the discharge point is at a
lower elevation than the recharge area
72
As mentioned early, groundwater flows from a recharge area to a discharge point. Generally, the discharge point is at a lower elevation than the recharge area. So, groundwater generally flows from a
higher elevation to a lower elevation
73
Discharge points may be a
spring or the bed of a river or stream
74
Discharge points may be a spring or the bed of a river or stream. Groundwater may also discharge along
the shore of a lake or beneath a lake or ocean
75
Discharge points may be a spring or the bed of a river or stream. Groundwater may also discharge along the shore of a lake or beneath a lake or ocean. So, we may find groundwater closer to
the surface if we drill near streams, rivers or lakes
76
Groundwater generally follows the
contours of the surface of the ground
77
Groundwater generally follows the contours of the surface of the ground. We may be more successful locating groundwater if we
drill a well at the bottom of a low point
78
Groundwater generally follows the contours of the surface of the ground. We may be more successful locating groundwater if we drill a well at the bottom of a low point, such as a .............. rather than
such as a ravine, rather than at the top of a mountain
79
Groundwater generally follows the contours of the surface of the ground. We may be more successful locating groundwater if we drill a well at the bottom of a low point, such as a ravine, rather than at the top of a mountain.
Generally we want to look at the lower elevations of the
surrounding topography, like in valleys, basins, or ravines, and also near rivers, streams, lakes, or ponds.
80
Geophysical methods of locating groundwater are technological ways of determining conditions below the ground surface without actually
drilling a hole
81
Each of these geophysical techniques measures a specific
physical property of the rock or sediment
82
Each of these geophysical techniques measures a specific physical property of the rock or sediment such as the
earth’s electrical resistance, electrical conductance, density, and magnetic properties
83
Each of these geophysical techniques measures a specific physical property of the rock or sediment such as the earth’s electrical resistance, electrical conductance, density, and magnetic properties. Changes in these properties can be related to
changes in the type of sediment or rock, potential for aquifers, and in some cases groundwater quality.
84
However, each of these geophysical methods has
limitations
85
However, each of these geophysical methods has limitations. These techniques cannot, by themselves, determine the
presence and location of an aquifer
86
However, each of these geophysical methods has limitations. These techniques cannot, by themselves, determine the presence and location of an aquifer. Data developed by geophysical methods must be compared with
nearby known geology to be accurately interpreted.
87
Electrical Resistivity
A resistivity survey measures the electrical resistance to a current induced into the ground
88
The ................................ or ............... depends on many factors
electrical resistance of sediment
rock
89
The electrical resistance of sediment or rock depends on many factors such as
particle size, porosity, density, mineral and chemical composition, and moisture level
90
The electrical resistivity of a particular formation depends on many factors and these have been discussed in detail earlier. Generally fine grained material such
clays or silts
91
The electrical resistivity of a particular formation depends on many factors and these have been discussed in detail earlier. Generally fine grained material such as clays or silts have
low resistivity
92
The electrical resistivity of a particular formation depends on many factors and these have been discussed in detail earlier. Generally fine grained material such as clays or silts have low resistivity, whereas .................................. have high resistivity
sands or gravels
93
Dry formations have .................. resistivity compared to
high
material lying beneath the water table
94
Water quality also affects
affects resistivity with saline water or water with higher concentrations of dissolved minerals having relatively low resistivity
95
Water contained within clay units is generally
highly mineralised
96
Water contained within clay units is generally highly mineralised, which contributes to its
low resistivity
97
It involves inducing a known electrical current into the ground via
two electrodes
98
It involves inducing a known electrical current into the ground via two electrodes, and evaluating the
resistivity of the ground material based on the measured potential difference in two other electrodes
99
Electric resistivity is a relatively
cheap method
100
Electric resistivity is a relatively cheap method and suited to
the gravel type aquifers
101
Electric resistivity is a relatively cheap method and suited to the gravel type aquifers, although the results it provides are a
simplification of nature
102
Earth resistivity is the
resistance of rock or soil to the passage of electric current
103
A
104
B
105
C
106
D
107
The following represents
electrical resistivity method
108
Electrical resistivity method
The method relies on different rock types having different
resistivity values
109
The method relies on different rock types having different resistivity values depending on their
density, porosity, water content and the quality of the water
110
The method relies on different rock types having different resistivity values depending on their density, porosity, water content and the quality of the water.
Thus the resistivity values are directly related to
the physical properties of the medium
111
Thus the resistivity values are directly related to the physical properties of the medium. Therefore this method is good for assessing the
bulk properties of different layers below the surface.
112
Clay minerals and water are good conductors of
current and exhibit low resistivity values
113
Clay minerals and water are good conductors of current and exhibit low resistivity values, whereas air is a
poor conductor
114
Clay minerals and water are good conductors of current and exhibit low resistivity values, whereas air is a poor conductor. If the pores are filled with water, the formation will be
least resistive
115
Clay minerals and water are good conductors of current and exhibit low resistivity values, whereas air is a poor conductor. If the pores are filled with water, the formation will be least resistive, particularly if it contains
saline groundwater
116
If the pores are filled with water, the formation will be least resistive, particularly if it contains saline groundwater. If the gravels are dry or empty they will be
very resistive
117
If the gravels are dry or empty they will be very resistive, but will be slightly less resistive if there is
a silt or clay matrix
118
If the gravels are dry or empty they will be very resistive, but will be slightly less resistive if there is a silt or clay matrix. An interpretation of resistivity soundings provide an indication of
the sub-surface sediments and the associated groundwater characteristics
119
. An interpretation of resistivity soundings provide an indication of the sub-surface sediments and the associated groundwater characteristics. However, it isn’t a ......................, and relies on a .....................................
direct measure
high degree of interpretation
120
Seismic Refraction
A seismic refraction survey measures how fast a “shockwave” travels through the ground
121
Because the waves travel at ........................ speeds
different
122
Because the waves travel at different speeds depending upon the
the density of the material they pass through, the timing of their arrival at the geophone
123
Because the waves travel at different speeds depending upon the density of the material they pass through, the timing of their arrival at the geophone can be interpreted to reveal something about the
density of materials at different depths.
