**SO422 Nearshore
Oceanography**

**Fall 2009 Exam
1**

Attachment:

Wave equations
table

This is an open book exam. You may use your text book and any notes you have permanently written in it. You may not attach any papers to the book, but you can tab the book.

You will be issued a calculator for the exam, and cannot use your programmable calculator.

Read all questions carefully. Full credit on the problems require that your
method be clearly identifiable. For the
short answer questions insure that your answer is complete and concise, and
covers the key points. You will be
graded by how well you show an understanding of the key concepts of the course.

5 definitions @4 20 ________

Problem 30 ________

short answers @5, 10 and
20 60
________

TOTAL 110 ________

Budget
your time. This exam can be done if you
know what you are doing, but do not waste time on a question you do not
understand. On the short answers note
that you have some choices on which questions to answer. Note also that the last short answer is worth
20 points, so you take more care in that answer.

**All work on this exam is
individual. You may not any materials
(books, notes, computers), and you may not use IM, texting, talking, or any
other means to communicate with other individuals.**

**Red comments are key
points, not complete answers.**

(20) Definitions. Briefly define 5 of the following terms with
no more than a single sentence showing that you clearly understand its
importance. If you use a mathematical
relationship, also explain its importance or significance:

·
Dissipative
beach profile:

·
Heavy
mineral:

·
Plunging
breakers:

·
Tombolo:

·
Active
continental margin:

·
Sediment
sorting:

·
Phi
scale:

(30) A wave has a period **T=8 sec**, and passes a wave gauge in
water **d=75 m** deep. At the gauge **H _{75}=4.0 m**, and the angle of
attack

(4) At what depths will this wave transition from deep to
intermediate depth, and from intermediate to shallow?

(5) What will be the wavelength of the wave at ** this** depth (the wave gauge)?

(2) What will be the speed of the wave at ** this** depth (the wave gauge)?

(5) What will be the orientation **a**_{0}**
**of the wave __in 10 m of
water__.

(6) What will be the height **H _{0 }**of the wave

(3) Will the wave break before or after reaching 10 m depth?

(5) Answer one of the following questions, for which you may
neglect refraction:

·
At
what depth would this wave have a speed of 5 m/sec?

·
At
what depth will this wave have its minimum height?

·
Is
there any way the wave could have the same height at two different depths?

Lo |
"1.56*T*T |
99.84 |
m |
|||

C0 |
1.56*T or Lo/T |
12.48 |
m/sec |
|||

Deep when D/Lo > 0.4981 |
D= |
49.7303 |
So 75 m is deep |
|||

Shallow when D/Lo < 0.0152 |
D= |
1.517568 |
||||

At D= |
10 |
|||||

d/Lo |
0.10016 |
|||||

Table |
||||||

d/L |
0.145 |
|||||

tanh |
0.722 |
|||||

Ks=H/Ho |
0.929 |
|||||

L |
Lo * tanh |
72.1 |
||||

L |
d/ (d/L) |
69.0 |
||||

c |
L/T |
7.2 |
6.9 |
|||

sin(alpha10) |
C10/C0 * sin(alpha0) |
|||||

sin(alpha0)*tanh |
||||||

sin(28)*tanh |
0.338958 |
0.324292 |
||||

alpha0 |
19.81343 |
18.92271 |
||||

KR |
0.968765 |
0.966122 |
||||

H10=KR * KS * H75 |
3.60 |
3.59 |
||||

5m/s |
5/Co |
0.400641 |
"=tanh" |
|||

Table, d/Lo |
0.027 |
|||||

d=0.035*Lo |
2.69568 |
|||||

Min Height |
Ks = 0.913 |
|||||

D/Lo= |
0.161 |
|||||

D= |
16.07 |
|||||

Short Answer. **Answer
the following questions as directed** with concise, complete answers. You should use appropriate terminology and
concepts.

Answer the question on this page. It is
worth 10 points.

1.
Which of these graphs could you use to discuss the changes that take
place in the wave for which you did computations on the last page? Which wave parameters follow this pattern of
change as the wave comes ashore?

Answer the question on this page.
It is worth 10 points.

2. This graph shows a size distribution analysis for three sand samples. Describe what each axis represents, and discuss three parameters that we use to quantify the relationships shown in the graph. Use two samples to show how each of the three parameters varies and what that means for the sand sample.

Answer two of the next three questions. Each is worth 10 points.

3. What determines the mineral composition of the sand on a beach? Discuss the general factors, and then list three minerals commonly found on beaches and the specific conditions that favor each.

_{2})

5. How does wave shape change as the wave
approaches the shoreline, and how does this affect sediment motion and sorting?

6. Answer this question, which is worth 20
points. Insure that you provide a
thoughtful answer that summarizes what we have learned in the first five weeks
of the course.

Use the diagram (fig 2-24 of Komar) above to show how a barrier island responds to changes in sea level and hurricanes.

Transgression/regression, and shift of environments (sediment size)