SO422
Nearshore Oceanography
Fall 2001 Exam
2
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 ________
6 definitions @5 30 ________
4 short answers @10 40 ________
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 6217301,
p.B91) was collected at Duck,
Phi Size 
Weight Percent 


2 
0.000 


1 
0.000 


0 
3.819 


1 
30.273 


2 
52.857 


3 
12.921 


4 
0.130 


Pan 
0.000 


(2) What parameters define the best
fitting lognormal distribution for this sand.
(2) Calculate the parameters that define
the best fitting lognormal distribution for this sand.
(4) How would changing each of these
parameters affect your graph on the next page?
(4) Calculate the parameter that
determines how well this sand fits the lognormal 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 will use in the wave tank
today has 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?
Phi Weight %
Retained Cum % Retained
2.00
0.00 0.00 0.00
1.00
0.00 0.00 0.00
0.00
3.82 3.82 3.82
1.00
30.27 30.27 34.09
2.00
52.86 52.86 86.95
3.00
12.92 12.92 99.87
4.00
0.13 0.13 100.00
5.00
0.00 0.00 100.00
Total weight 100.00
Phi16= 0.57
Phi50= 1.27 Phi84= 1.92
Mean= 1.25
Sigma (Std dev)= 0.67 Alpha (skewness)=0.02
Median is Phi50 = 1.27
Phi50 = log(2)
dia mm
Phi50 = log(2)
dia mm
2^(Phi50)
= 2^( log(2) dia mm)
2^(1.27)
= dia mm
0.41 mm = diameter
0.32 mm is 1.64 Phi (log10(0.32)/log10(2)),
which is Phi71, making 71% of the sand larger than this.
(10). Complete the survey notes for a
group at Assateague
The survey team starts with the rod at BM02 in the parking lot (elev 3.00) and the level halfway to the dune; the reading on the rod 1.63. They then take 3 readings at stations 5 m (reading 2.14), 10 m (reading 2.37), and 15 m (reading 2.98) away from the BM. They then move the level to the top of the dune and take a reading (0.87) with the rod still on the 15 m station.
Station 
B.S. 
H.I. 
F.S. 
Elev 
Dist 










































Station 
BS 
HI 
FS 
Elev 
Dist 
BM 
1.63 
4.63 

3 
0 



2.14 
2.49 
5 



2.37 
2.26 
10 

0.87 
2.52 
2.98 
1.65 
15 
2.
Definitions: with a single complete sentence, define 6 of the
following terms. Show that you clearly
understand the concept involved.
· LonguetHiggins equation:
·
Bruun rule:
·
Rip current:
·
Cusp:
·
Closure depth:
·
Critical basal shear stress:
·
Regression:
·
Sink:
There
are 6 short answer questions in part 3.
You must answer 4 of them. Each
is worth 10 points. For full credit you
must cover the important topics and use the correct terminology.
3a.
This image is part of the "Duck Movie" we
saw in lab.
·
Why do scientists take two different types of images for these movies?
·
What interesting feature is shown in this image?
3b. What is the
difference between the black minerals in the beach at Assateague and those of a
black sand beach in
3c. How does sediment movement vary in the marsh and under waves on the front side of a barrier island? Why does this happened and why is it important?
3d. How will a barrier island respond to sea level rise, and what will be the vertical pattern of sedimentary facies that you would see as a result?
3e. How would you go
about creating a budget for a typical coastal cell, and what would you expect
to be the major contributors in the main categories?
3f. Describe the
process depicted in this diagram.