Course: ERSC 2P10
April 15, 2002
Name:
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page 1 of 9
Student number:
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Brock University
Final Exam, April 2002
Course: ERSC 2P31
Date of Examination: April 15, 2002
Time of Examination: 1900-2200h
Number of pages: 9
Number of students: 15
Number of Hours: 3
Instructor: R.J. Cheel
Instructions: Questions in Parts A and B are to be answered on the examination paper. Please hand this
paper in at the completion of the exam.
No Examination aids are permitted. Use or possession of unauthorized materials will automatically result in
the award of a zero grade for this examination.
Part A. Fill in the appropriate word, phrase or value in the each of the spaces provided (1 mark each, total 15
marks).
A1. The nominal diameter of a particle is the longest distance that nominally passes through the particle. True
or False (circle one)
A2. The measure of the symmetry of a grain size distribution is termed
..
A3. A sandstone that contains 45% matrix is generally termed a
..
A4. The first bedforms to develop just as an oscillatory current can begin to move the bed material are
.
termed
A5. Sediment that goes into transport in suspension, only when a river is in flood, is termed the
.
A6. Shields' criterion for the initiation of motion of a particle will underestimate or overestimate the critical
boundary shear stress required to move a particle over a bed of much larger particles?
.
A7. Porosity and permeability both increase as the grain size of the material increases.
True or False (circle one).
A8. Wave-formed ripples with ripple spacing that is much smaller than the diameter of the wave
orbital are termed
.
Course: ERSC 2P10
Name:
April 15, 2002
.
page 2 of 9
Student number:
A9. The form of cross-stratification shown in the following figure is termed
..
A10. The process by which high speed fluid is swept towards a boundary and low speed fluid is
ejected away from the boundary is termed
.
.
A11. The upper flow regime is characterized by bedforms that are in phase with the water surface.
True or False (circle one)
A12. As grain size decreases so does porosity. True or False (circle one)
A13. Swaley cross-stratification is produced by the action of unidirectional currents.
True or False (circle one)
A14. Only the density of a particle determines its settling velocity. True or False (circle one)
A15. This is the last question in Section B of this exam. True or False (circle one)
Course: ERSC 2P10
April 15, 2002
Name:
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page 3 of 9
Student number:
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Part B. Complete the task required for FOUR of the following in the space provided. (5 marks
each, total 20 marks)
B1. In the spaces below fill in the appropriate name of the various flow types.
Combined flows
Flow Class:
Resultant Flow
Velocity (cm/sec)
50
0
50
5
10
-50
50
0
-50
Flow components
5
10
0
50
5
10
0
50
5
10
0
50
5
10
0
-50
-50
-50
-50
50
Unidirectional 50
component
50
50
0
5
10
-50
0
5
10
-50
0
-50
Oscillatory component
Time (seconds)
5
10
0
-50
5
10
5
10
Course: ERSC 2P10
April 15, 2002
Name:
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page 4 of 9
Student number:
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B2. The following figure illustrates the forms of ripples that develop under unidirectional flows. On
the lines above the picture of each ripple type state the specific term for that ripple form. On the lines
beneath each picture indicate the relative position of each ripple type in the sequence from lowest flow
strength (1) to highest flow strength (5) for which each ripple type is thought to form.
Discriptive term
for crest-line
Plan-view shapes
of ripples
Relative flow strength
and/or duration
(1=lowest strength, 5=highest strength)
B3. The figure below shows the fields of bedform stability under combined flows. On the dashed lines
provided print the appropriate name for each bedform and in the boxes provided draw the appropriate
sketch to illustrate the bedform and its internal cross-stratification.
0.6
0.4
Tran
siti
on
0.2
a
l
Maximum orbital speed (m/s)
0.8
?
no movement
0
0
.04
.08
.12
.16
.20
Unidirectional current speed (m/s)
.24
Course: ERSC 2P10
April 15, 2002
Name:
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page 5 of 9
Student number:
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B4. The graph below shows the fields of stability of bedforms under 0.3 m deep unidirectional
flows. Fill in the dashed lines as appropriate to complete the figure.
10˚C-equivalent mean flow velocity (m/s)
4.0
2.0
F=
F=
Transition
ual
1.0
d
Gra
Abrup
t
0.8
Abr
up
t
0.6
ual
d
a
Gr
l
ua
d
a
Gr
0.4
0.2
?
D = 0.30 m
0.1
.06
0.1
0.2
0.4
0.6
1.0
10˚C-equivalent sediment size (mm)
2.0
Course: ERSC 2P10
Name:
April 15, 2002
.
page 6 of 9
Student number:
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B5. Figure 4 shows a sequence of forms of ripple cross-stratification that may be interpreted in
terms of flow conditions over the time that it formed. In the space provided outline the details of
how this sequence might reasonably form.
10 cm
Figure 4.
.
.
.
.
.
.
.
.
.
.
.
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Course: ERSC 2P10
Name:
April 15, 2002
.
page 7 of 9
Student number:
Part C. Anwer two of the following questions in the booklets provided. (20 marks each, total 40
marks).
C1. Explain the relationshp between porosity and permeability.
C2. Describe the sequence of bedforms that develops under unidirectional currents, in the order in
which they would appear with increasing flow strength.
C3. Describe the various ways in which sediment is transported and draw a diagram to illustrate
how grain size distributions may be interepreted in terms of transport modes.
.