See answers to calculations at bottom of web page.

SO422 Nearshore Oceanography

Spring 2001 Exam 2--AM version

Attachments:

Wave tables.

Read all questions carefully.  The definitions should be a complete sentence that fully explains the term.   For the short answer questions insure that your answer is complete and concise, uses appropriate terminology,  shows that you understand any terms used, and covers the key points.  The quality of your answer is critical, and not just a general understanding of concepts.

Problems                    30  ________

5 definitions @4            20  ________

5 short answers @10         50  ________

TOTAL                      100  ________

Note that you must answer 5 of the definitions and 5 of the short answer questions.  Insure that you do not waste time answering more than the required number in each section.

1. Problems:

The following sand (sample 6216311, p.B49) was collected at Duck, North Carolina:

 Phi Size Weight Percent -2 0.000 -1 0.081 0 0.692 1 4.029 2 3.980 3 81.949 4 9.269 Pan 0.000

(4) Calculate and clearly label the parameters (and only those parameters) that define the best fitting log-normal distribution for this sand.

(4) How would changing each of these parameters affect the graph on the next page?

(4) Calculate the parameter that determines how well this sand fits the log-normal distribution, and compare that result with a graphical measure.

(4) What is the size in mm of the median sand size?

(4) The sand we used in the wave tank last week had a median size of 0.32 mm.  What is this size in phi units, and what percentage of the sand from Duck is larger than this size?

(10). Complete the survey notes.

The survey team starts with a back sight (reading on the rod 1.56) to BM01, elev 3.00.  They then take 3 readings at stations 5 m (reading 2.34), 10 m (reading 2.56), and 15 m (reading 2.74) away from the BM.  They then move the level and take a reading (1.21) with the rod still on the 15 m station.

 Station B.S. H.I. F.S. Elev Dist

2.  Definitions: with a single complete sentence, define 5 of the following terms.

a)      Longuet-Higgins equation:

b)      Groin:

c)      Rip current:

d)      Cusp:

e)      Setback:

f)        Closure depth:

There are 7 short answer questions.  You must answer 5 of them.

3a.   This image is part of the "Duck Movie" we saw before spring break.

• How was the image created?
• Why do scientists take these movies?
• What interesting feature is shown in this image?

3b.  This  figure (7-26)  shows profiles taken in Lake Michigan in July 1970.

• What does this diagram illustrate?
• What wave conditions were probably in effect during this time?
• How was the beach classification changing during this time?

3c.  Label this diagram (fig 8-3) , and explain what it shows.

3d.  Which would effect the velocity of the longshore current more (defend your answer):

• Changing the breaker height from 3 m to 5 m,
• Changing the angle of attack of the breakers from 4 to 12 degrees.

3e.  This figure (9-2) shows the situation in Santa Monica.  What natural process is occurring, and what effect did the engineering structure have on it?  What should be the response to this situation?

3f.  This diagram (Fig. 9-9) shows longshore transport along the East Coast.  From the data shown, where do the major sinks and sources appear to be located?  Defend your answer.

3g.  This diagram shows the bars we created in the wave tank last week.

• Where did the sand come from that created the bar?
• How was the classification of the profile changing over the course of the experiment?
• What happens below the one foot water depth?
• Why does the slope change between 17 and 18 feet on the horizontal scale?

SO422 Nearshore Oceanography

Exam 2--PM version

Attachments:

Wave tables.

Read all questions carefully.  The definitions should be a complete sentence that fully explains the term.   For the short answer questions insure that your answer is complete and concise, uses appropriate terminology,  shows that you understand any terms used, and covers the key points.  The quality of your answer is critical, and not just a general understanding of concepts.

Problems                    30  ________

5 definitions @4            20  ________

5 short answers @10         50  ________

TOTAL                      100  ________

Note that you must answer 5 of the definitions and 5 of the short answer questions.  Insure that you do not waste time answering more than the required number in each section.

1. Problems:

The following sand (sample 6216311, p.B49) was collected at Duck, North Carolina:

 Phi Size Weight Percent -2 0.000 -1 0.081 0 0.692 1 4.029 2 3.980 3 81.949 4 9.269 Pan 0.000

(4) Calculate and clearly label the parameters (and only those parameters) that define the best fitting log-normal distribution for this sand.

(4) How would changing each of these parameters affect the graph on the next page?

(4) Calculate the parameter that determines how well this sand fits the log-normal distribution, and compare that result with a graphical measure.

(4) What is the size in mm of the median sand size?

(4) The sand we used in the wave tank last week had a median size of 0.32 mm.  What is this size in phi units, and what percentage of the sand from Duck is larger than this size?

(10). Complete the survey notes.

The survey team starts with a back sight (reading on the rod 1.56) to BM01, elev 3.00.  They then take 3 readings at stations 5 m (reading 2.34), 10 m (reading 2.56), and 15 m (reading 2.74) away from the BM.  They then move the level and take a reading (1.21) with the rod still on the 15 m station.

 Station B.S. H.I. F.S. Elev Dist

2.  Definitions: with a single complete sentence, define 5 of the following terms.

g)      Longuet-Higgins equation:

h)      Groin:

i)        Rip current:

j)        Cusp:

k)      Setback:

l)        Closure depth:

There are 7 short answer questions.  You must answer 5 of them.

3a.   This image is part of the "Duck Movie" we saw before spring break.

• How was the image created?
• Why do scientists take these movies?
• What interesting feature is shown in this image?

3b.  What fundamental relationships about beaches does this figure (fig 7-16 ) illustrate?

3c.  Label this diagram (fig 8-3) , and explain what it shows.

3d.  Which would effect the velocity of the longshore current more (defend your answer):

• Changing the breaker height from 1 m to 2 m,
• Changing the angle of attack of the breakers from 5 to 15 degrees.

3e.  This figure (9-4) shows the situation in Santa Barbara.  What natural process is occurring, and what effect did the engineering structure have on it?  What should be the response to this situation?

3f.  This diagram (Fig. 9-9) shows longshore transport along the East Coast.  From the data shown, where do the major sinks and sources appear to be located?  Defend your answer.

3g.  This diagram shows the bars we created in the wave tank last week.

• Where did the sand come from that created the bar?
• How was the classification of the profile changing over the course of the experiment?
• What happens below the one foot water depth?
• Why does the slope change between 17 and 18 feet on the horizontal scale?

Phi     % Retained  Cum % Retained   Cum % Passed

-2.00         0.00      0.00           100.00

-1.00         0.08      0.08            99.92

0.00         0.69      0.77            99.23

1.00         4.03      4.80            95.20

2.00         3.98      8.78            91.22

3.00        81.95     90.73             9.27

4.00         9.27    100.00            -0.00

5.00         0.00    100.00            -0.00

Phi16= 2.14   Phi50= 2.51   Phi84= 2.87

Mean= 2.51    Sigma (Std dev)= 0.37    Alpha (skewness)=-0.00

Median = Phi50 = 2.51 = 0.18 mm

0.32 mm is 1.64 Phi, which is Phi7, making 7% of the sand larger than this.

 Station B.S. H.I. F.S. Elev Dist BM01 1.56 4.56 3.00 0 2.34 2.22 5 2.56 2.00 10 1.21 3.03 2.74 1.82 15