4F Coastal study trip: San Bartolo and Pucusana
NAME:
SET:
During the day you will visit San Bartolo and Pucusana. You will take part in a variety of
fieldwork activities where you will collect data which you will use to prove or disprove
the following hypotheses:
1.
2.
3.
4.
5.
The larger the beach material, the steeper the gradient of the beach
The groynes at San Bartolo disturb natural patterns of Longshore drift
The form of the beach is consistent with the type of wave observed
Direction of Longshore drift is the same as wave attack
The functions of Pucusana are directly related to its physical geography
SAN
BARTOLO
Sandy beach.
You would
expect it to have
a gently sloping
gradient.
Shingle
beaches. These
should have a
steeper
gradient.
What effect do these
groynes have?
PUCUSANA
Harbour for fishing
boats
The cove known as
“El Boqeron”
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WAVE STUDY - WAVE DIRECTION and FREQUENCY
To help with deciding whether or not Longshore Drift occurs at our beach, calculating
the direction of the waves can prove to be very useful. To do this stand at the edge of
the shore and move around until the waves are coming directly towards you. Take the
compass direction from north at this point. This will give you the direction of the waves.
Also record the direction of the wind.
Wave Direction
Wind Direction
We need to know whether the waves are destructive (erosional) or constructive
(depositional). Destructive waves ten to break at more than 13 waves per minute, while
constructive waves tend to break at less than 13 waves per minute.
Using a stop watch, count the number of waves over a ten minute period and take the
average. (i.e. divide the answer by 10 to get the average number of waves per minute).
WAVE FREQUENCY
TALLY CHART
NUMBER OF
WAVES OVER 10
MINUTES
WAVES ARE
Now compare the beach you are sitting on with the diagrams on the last page of this booklet.
Are the features of this beach consistent with the type of waves you have observed? Make
notes of similarities and differences.
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LSD – MEASURING LONGSHORE DRIFT
We need to measure the rate of longshore drift. Try to follow these instructions





Make a fixed central mark on the beach in front of the advancing tide.
Measure and mark off 10 meters from this central mark in both directions at right
angles to the beach and parallel to the sea.
Throw a satsuma or similar bio-degradable object that will float into the sea exactly
opposite the central mark. This needs to be seen.
Count the time it takes in seconds before the advancing and retreating waves move
the cork so that it passes one of the 10 meter markers.
In order to make this a fair test, repeat the experiment four times, or until you are
satisfied that the material is being moved along the beach consistently in one
direction.
Longshore Drift
Time taken to travel 10 metres
(in seconds)
1
2
3
4
Now you will need to calculate the average rate in metres per second of the longshore
drift. Use the formula below to help you:
A=Total Time taken (add up the 4)
Seconds
B=Average time taken (divide by 4)
Seconds
C=Divide distance covered by the
average time taken (10 ÷ B)
Direction of Longshore Drift
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Meters
per second
BEACH SURVEY (PROFILE)
You need to take a Beach Profile. This tells us the shape and the characteristics of the
beach.



Lay down the tape measure at right angles to the beach.
Using the ranging poles take measurements of the angle of the slope every 3 metres.
Record these on the table below.
Profile U: Material type:
Meters
from
sea
Angle
of
slope
0
3
Beach width:
6
9
12
15
18
Profile V: Material type:
Meters
from
sea
Angle
of
slope
0
3
0
3
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24
27
Beach width:
6
9
12
15
18
Profile W: Material type:
Meters
from
sea
Angle
of
slope
21
21
24
27
Beach width:
6
9
12
15
18
21
24
27
Profile X: Material type:
Meters
from
sea
Angle
of
slope
0
3
Beach width:
6
9
12
15
18
Profile Y: Material type:
Meters
from
sea
Angle
of
slope
0
3
0
3
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24
27
Beach width:
6
9
12
15
18
Profile Z: Material type:
Meters
from
sea
Angle
of
slope
21
21
24
27
Beach width:
6
9
12
15
18
21
24
27
FIELD SKETCH OF PUCUSANA BAY
Draw the outline of Pucusana Bay first. Then add in the detail. Add in notes and annotate the diagram. Use these to help you:
Headland; Bay; Soft Rock; Hard Rock; Steep Slopes; flat land; Erosion; Deposition; Cliffs; Transportation; Poor quality housing;
Housing; Port; Businesses; also add in other relevant things you see.
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FIELD SKETCH OF COVE AT PUCUSANA
Draw an outline of the Arch and Bay. Add notes at the side to describe how this has formed and developed.
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YOUR PROJECT WRITE UP
You will need to write up your project. This should be done using the framework given to you below.
TITLE
“A STUDY OF COASTAL PROCESSES AND ENVIRONMENTS”
STRUCTURE
On the trip you collected four sets data i.e. you conducted three experiments. These were the Beach survey, the
LSD study, and the wave study. You should write up each experiment separately, except for the beach survey
and wave study, which go together. Describe the method, present your results, analyze your results, reach a
conclusion which refers to the hypothesis and finally evaluate your method and results.
HYPOTHESES
These are statements of what you expect to discover. What you expect to be the case should be based upon
what you have learnt about the processes that operate at the coast.
The hypotheses for each experiment are given below:
Beach survey/Wave study:
The larger the beach material, the steeper the gradient of the beach
The groynes at San Bartolo disturb natural patterns of sediment transfer
The form of the beach is consistent with the type of wave observed
LSD study:
Direction of longshore drift is the same as wave attack
Coastal Environments study: Pucusana
The functions of Pucusana are directly related to its physical geography
METHOD
For each of the studies above, you will need to explain how you did the field work (data collection) and then why
you did it like this. Diagrams could be useful.
RESULTS
In this section you will need to present your results in a variety of forms. You will need to use a variety of
techniques, present your work in as neat a way as possible, and make good use of diagrams when writing up your
work. Here are some suggestions:
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Beach survey:
Draw a beach profile
A table of the wave data
LSD study:
A proportionally drawn arrow to show speed and direction of LSD or table
Coastal environment study
Sketches and photos
ANALYSIS
When you have completed all your results you will now need to write about them. The best way to do
this is to do the following for each result;


Describe what it shows in detail. What are the highest and lowest figures? What is the overall pattern
that you can see?
Are your results what you expected? Offer explanations for your results?
CONCLUSION
For each piece of work that you have done you need to draw a conclusion. Your conclusion should refer to your
hypothesis. E.g. for the Beach study; the steeply sloping beach observed is consistent with the destructive waves
measured on the day and the large size of the beach material.
EVALUATION
Here you will need to be objective about your study. How well did your project work? Were your results
representative of the area, or were they just a freak of nature? Could you have improved your collection of
results in any way? How? What were the advantages and disadvantages of collecting material in this way? Are
there any other factors that have affected your results?
Good Luck!
Remember to use the information on the following pages to help you complete this project. Pay special
attention to the marking guidance so that you can evaluate the quality of your own work.
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Year 4 Coastal Theory sheet
This note sheet is designed to give you the theory you need to know and understand for the coastal study fieldtrip write-up.
You will have to apply this theory yourselves in order to show an adequate understanding and achieve a good
score.
Counting waves:
This may seem like an excuse to sit on the beach and watch the ocean but there is a geographical purpose! If on
average more than 13 waves break per minute then you can be reasonably sure that they are destructive waves.
If it is less than 13 per minute they are most likely constructive waves. Constructive waves have a strong swash
and a weak backwash so they move material up on to the beach, therefore ‘building’ the beach. These waves
produce a gently sloping beach. Destructive waves are the opposite.
Because the swash is stronger with constructive waves it has more energy to move material up the beach than
back down the beach. For that reason larger material can be moved up the beach but not back down. When
constructive waves are at work you can expect to find larger material at the top of the beach and finer material
at the bottom (nearest the sea) of the beach. The beach should also be more steeply sloping.
Measuring long-shore drift.
Long Shore Drift (LSD) is the process by which material is moved along the beach by waves. You would expect
the material to be moved in the same direction as the waves. You know the direction of the waves because you
measured the angle from which the waves approached.
Remember that the swash moves material up the beach at an angle but the backwash drags it back down at a 90
degree angle to the beach.
Beach form
Shingle beaches are steeper because there are large gaps between each stone allowing the wave to percolate
through. This increased percolation weakens the backwash meaning that the stones are not dragged down the
beach. Sandy beaches are gently sloping because the gaps between each sand particle are small, therefore
reducing percolation. The backwash is not weakened and sand is dragged back down by the backwash which has
the effect of evening out the slope of the beach.
Destructive and constructive waves produce different beach forms. The diagrams below will help you identify
the beach features you should expect to find.
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Beach profiles created by different wave types
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San Bartolo and Pucusana fieldwork write-up evaluation
rubric:
Presentation of results
Description
Graphs, sketches etc nearly always have a full title, key, scale where
appropriate. Presentation method is appropriate. Student has
included all suggested presentation techniques plus at least one of
their own design. Graphs, sketches etc are neatly and accurately
drawn.
Graphs, sketches etc usually have a title, key, scale where
appropriate. Presentation methods are usually appropriate. Student
has included all suggested presentation techniques. Graphs,
sketches etc are neatly drawn.
Data is presented. Graphs etc often don’t have titles, are often
inaccurate and/or are untidily drawn.
Very limited or no attempt to present data
Mark
18-20
14-17
10-13
5-9
Analysis
Description
Results are fully analyzed with data quoted in support. Patterns are
identified. Results are comprehensively explained to show
knowledge and understanding of the topic. Reasons should be
offered to explain unexpected results.
Results are analyzed. Patterns are sometimes identified. Some
explanation to show knowledge and understanding of the topic.
Reasons may be offered to explain unexpected results.
Description of results, briefly or weakly explained.
Incomplete or very brief description of results.
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Mark
18-20
14-17
10-13
5-9
Conclusions and Evaluation
Description
Conclusions are clearly and correctly drawn. Conclusions refer to the
hypothesis to state if it has been proven correct or not.
Thoughtful evaluative statements are made which consider the value
of the methods used, the way in which experiments were carried
out, and any external factors which may have affected the results.
Unexplained results should be referred to.
Conclusions are correctly drawn. Conclusions may refer to the
hypothesis to state if it has been proven correct or not.
Attempts are made at evaluation. Statements may consider the
value of the methods used, the way in which experiments were
carried out, and any external factors which may have affected the
results.
Conclusions are drawn. Very basic evaluation.
Incomplete and/or largely incorrect.
Mark
18-20
14-17
10-13
5-9
Overall presentation
Description
Project is complete. Very few spelling errors. There may be some
grammatical errors. All work is neatly presented.
Project is complete. Some spelling errors and grammatical errors.
Most work is neatly presented.
Project is mostly complete. Work clearly has not been checked with
frequent errors. Work may be untidy with little care taken.
Fragments of work handed in.
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Mark
18-20
14-17
10-13
5-9