Module 3 Summative Assessment Worksheet
Note: Because this exercise has so many steps, we wanted to make it easy for you to print off
the entire exercise to have available as you follow the directions. As a result, this worksheet is
a little different than the others. You only need to turn in the last page of this worksheet. You
can just copy and paste the questions into another Word document once you have answered
them.
Beach Profiling Exercise
Beaches evolve or change over time due to both natural forces and man-made
engineering. Coastal geologists and engineers evaluate how sediment is deposited, eroded, and
transported along coastal beaches and barrier islands to better understand the processes that drive
these kinds of changes. One method that is commonly used to evaluate and understand beach
evolution and sediment transferal is to repeatedly measure the elevation of the beach. This can
be done a number of different ways but one of the quickest and cheapest methods is to use the
Emery beach profiling technique, which was developed by K.O. Emery in 1961.
This YouTube video provides a good explanation of the procedure that is used to obtain data for
the elevation of a beach.
http://www.youtube.com/watch?v=NaF7Pq2HkxA
Here is another link describing Emery (1961) method of beach profiling:
http://www.whoi.edu/seagrant/page.do?pid=52235&tid=282&cid=88638
Collected data can be plotted to show a cross sectional profile of the beach at the time of
surveying. If the beach is surveyed multiple times at different time periods, a record of the
changes in the cross sectional picture of the beach emerges. Comparing the cross sections for
different survey dates enables one to determine whether the elevation of the beach has been
locally reduced because of erosion or if the elevation of the beach has locally increased, implying
deposition at this location. Take a look at this enlarged plot from the previous link to fully
understand the type of cross sectional plot that can be created with the beach profiling technique
http://www.whoi.edu/cms/images/rexhame2_126638.gif
Moreover when multiple profile transects are set up and surveyed repeatedly along the
length of a beach then it is possible to determine how different sections of the beach evolved. For
example, suppose you have two different profiles set up along a beach with 1 kilometer spacing
between them. At the first profile location, repeat surveys show that there is net erosion on the
beach face, whereas at the second profile location, a kilometer away, there was deposition. One
might interpret the increase of sediment volume at the second profile a result of sediment being
eroded from the first location and transported to the second location.
In this exercise you are given beach profile survey data for three different transects along
Integrate Island. The three transects are 500 m apart from one another and each transect was
surveyed three times (Fig. 1). The first survey was completed on February 1, 2008 to establish a
baseline elevation dataset for each profile location. The second survey was completed on
September 9, 2008. Although the second survey was only 6 months after the first survey there
was a category 3 hurricane late in the summer of 2008. Hurricane Alberto made landfall just 100
km away from Integrate Island and caused significant changes to the elevation of the island due
to large waves created by a 2m storm surge produced by the passage of Hurricane Alberto. The
final survey was completed on November 1, 2009.
Figure 1. Location of the three elevation transects surveyed on Integrate Island. The image was
taken the day of initial survey on February 1, 2008.
Your goal for this exercise is to take the raw survey data for the island and plot it in
Excel. When finished you will have three different plots, one for each beach profile transect, and
each plot will have three different elevation profiles overlain upon one another so that you
compare the changes in elevation for the three time periods (one for 02/01/2008, one for
9/9/2008, and one for 11/01/2009). Once you have all three plots constructed you can answer the
questions that are at the end of this assignment.
Steps to Complete the Exercise
An instructional video is included here to show you how to plot the data in Excel so that
you make the final interpretations but here is also a step by step write up of how to plot the data.
Preparing the Data for Plotting
1) Open up the attached Excel file and save it locally to your desktop or relevant folder with
the naming convention: yourname_IntegateIsland_BeachProfiles (e.g.
mkulp_IntegateIsland_BeachProfiles)
2) Now click on the Profile Data tab at the bottom of the page to open up the worksheet with
all of the raw data.
3) On this sheet you will see boxes containing all of the profile data for each transect across
all of the survey dates
4) For each survey date there are the following columns:
Transect 1
Horizontal
Distance and
Elevation Change
Date of Profile Survey
Feb 01,2008
Horizontal
Distance
Measured(m)
Elevation Change
Measured (cm)
0
3
3
3
3
3
0
60
-20
40
-16
-56
cumulative
distance of
transect (m)
cumulative
change in
elevation for
transect (cm)
Back Stake Height
(m)
0.98
Each pair of readings for the horizontal distance and elevation change represents the amount
of horizontal distance moved and the elevation change represents the amount of elevation change
that was observed with the survey rods across this horizontal distance. Notice that the first
measurements in all cases are 0,0 and that the next measurement is thus relative to those initial
starting values of distance and elevation. The column for Back Stake Height represents the
measured elevation between the top of your back survey stake to the ground, in this case there
was 0.98 distance between the top of the stake and the top of the island surface.
5) The next step is to calculate the cumulative changes that were observed. These values
will be placed in the rows directly below cumulative distance of transect and
cumulative change in elevation for transect.
6) First put 0’s in the first row below the headings cumulative distance of transect and
cumulative change in elevation for transect (these will be cells D4 and E4,
respectively). This represents the starting point of your profile.
7) Now you will have to determine the cumulative distance and cumulative elevation
changes indicated by the first set of distance and elevation readings during the survey.
8) Next, you will need a formula for D5 that will add the value of the first horizontal offset
to the starting point of 0. In Excel this can be calculated in cell D5 using the following
formula: =B5+D4
9) Hit enter and if done correctly the value in D5 should now be 3 because 0+3= 3
10) Now in D6 you will be adding the value of D5 to the measured horizontal distance of cell
B6. So in D6 input the formula: = B6+D5 and the result should be 6.
11) You can continue this for the rest of the cells in the cumulative distance of transect
column for the first survey date To save time you can simply copy the formula from
cell D5 and paste it in the rest of the cells for the remaining cumulative distance of
transect (be sure to stop at D34 in that column otherwise you will overwrite the first
value of the next survey).
12) In order to determine the cumulative change in elevation for transect along the profile,
you will need to enter the following formula: =E4+C5 in cell E5
13) Continue this process for all of the rows below cumulative change in elevation (be sure
to stop at E34 in that column otherwise you will overwrite the first value of the next
survey).
14) If you have done everything correctly your cumulative columns should be populated with
the following values in the first six rows.
Transect 1
Horizontal
Distance and
Elevation Change
Date of Profile Survey
Feb 01,2008
Horizontal
Distance
Measured(m)
Elevation Change
Measured (cm)
cumulative
distance of
transect (m)
cumulative
change in
elevation for
transect (cm)
0
3
3
3
3
3
0
60
-20
40
-16
-56
0
3
6
9
12
15
0
60
40
80
64
8
Back Stake Height
(m)
0.98
15) Now we need to do this for the other survey dates of 09/09/2008 and 11/01/2009. Look at
the table below and you will notice that in your spreadsheet the back stake height
measured on 09/09/2008 was only 0.70 m compared to the first survey date when it was
0.98. This means that between the two surveys the distance between the top of the survey
stake and the island surface decreased by 0.28 m because of deposition of 28 cm
(equivalent to 0.28 m) of sand
9/09/2008 Post Hurricane Alberto
0
3
5
2.5
6
0
2
-10
-6
-17
0
3
8
10.5
16.5
28
30
20
14
-3
0.7
16) This change in elevation at the starting point of the back stake needs to be accounted for
by putting the following formula in cell E35: =(F4-F35)*100
17) This formula subtracts the value of the measured stake height on 09/09/2009 (0.7 m)
from the value on the first survey date (0.98 m) and yields a total reduction of 0.28 m in
elevation due to deposition. Notice that in the formula for E35 the value of subtraction is
multiplied by 100 to convert the values of stake heights that are in meters to centimeters,
which is the unit used for the measurements of elevation change made in the field with
the Emery rods.
18) Now complete the rest of the cumulative change rows for the 09/09/2008 survey date just
as you did for the 02/01/2008 survey date.
19) If you have done everything correctly your spreadsheet for transect 1 should like the table
below.
9/09/2008 Post Hurricane Alberto
0
3
5
2.5
6
6
6
3
3
3
3
3
0
2
-10
-6
-17
-10
-14
-7
-6
5
7
-50
0
3
8
10.5
16.5
22.5
28.5
31.5
34.2
35.9
40.3
45.7
28
30
20
14
-3
-13
-27
-34
-40
-35
-28
-78
0.7
20) Using these steps fill in all of the cumulative change rows for all of the profile survey
dates of the three profile transects and you are now ready to begin plotting the data.
21) One thing to keep in mind is that the first value of cumulative change in elevation for the
second and third surveys of a transect is actually the difference in height between the
back stake height during the first survey and the second and third surveys. This value is
already placed in the spreadsheets and all you will have to do is determine the rest of the
cumulative values.
Preparing the Data for Plotting
1) Click on the tab PROFILE PLOT SHEET.
2) At the top of the page click on the tab INSERT and select “Scatter Plot with Straight
Lines” option from the dropdown list.
3) A blank plot should appear on your worksheet
4) Now click on the chart and then right click your mouse. A window will pop up that has a
line “Select Data”. Click this and a new box will appear that allows you to specify which
data you want to plot.
5) On the left hand side of the “Select Data Source” box, click on the “add” button and a
new box entitled “Edit Series” will appear. Place your cursor in the line for “Series
name”. Now click on the PROFILE DATA Tab and find the cell with the first survey
date (cell A4). Click on this cell and the “Series name” line will be populated.
6) Next click in the area for “Series X values”. Then click on the PROFILE DATA tab and
move your cursor to cell D4, which is the first value of the cumulative horizontal
distances. Hold your mouse button down and drag all the way to the end of the
cumulative horizontal distance column for that survey date.
7) Now click in the “Series Y values”. Delete anything that is in that box and replace it with
an equals sign. Now click on the PROFILE DATA tab, click in cell E4 of the cumulative
change in elevation column and again while holding your mouse button down drag to
the end of the column for that survey date.
8) Now hit “ok” and the Select Data Source box should still be open. Click "Add“ to add the
next survey date and repeat the above process for the September 09, 1008 dataset.
Repeat this procedure to include the third survey data. The final plot should look similar
to the one shown in figure 1.
9) You will have to add axes titles, as well as, a title at the top of the chart. This can be
achieved by clicking on the “Chart Tools Layout” tab where additional buttons will
appear for “Chart Title” and “Axis Titles”.
10) If you right click on the chart, a dropdown list will appear. Choose “Format Chart Area”
to set the size of the chart to be 5” height and 9” width. All of your charts should be the
same size and the axis lengths should all be the same as well. Axis lengths can be
adjusted by right clicking on each individual axis to highlight it, and then choose “format
axis” option where you can set the range of values for that axis. The horizontal axis
should span 0 to 100 and the vertical axis should range from 180 to -200. You also need
to make sure that the X axis of the plot (horizontal distance) crosses the Y axis (relative
elevation) at the -200 value of the Y axis. To do this go to format the Y axis and you will
see an axis value setting where you can change it from “fixed” to “axis crosses at”, type
in -200.
11) Follow these steps for all three transects and then answer the questions at the end of this
assignment.
Relatvie Elevation (cm)
Integrate Island_Transect_01
180
160
140
120
100
80
60
40
20
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
Feb 01,2008
9/09/2008 Post
Hurricane Alberto
Nov 01,2009
0
10
20
30
40
50
60
70
80
90
100
Horizontal Distance (m)
Figure 1. Plot of the first transect for three different survey dates that is properly adjusted
for colors, labels, main and axes titles, as well as horizontal and vertical scales.
Summative Assessment Questions:
Assessment Questions: Be sure to include the three transect plots that you created when
you hand in the answers to these questions.
1. During which of the time periods are the sand dunes of the island most evident in the profile
data?
2. Which of the profile transects had the highest sand dunes during this time period?
3. Which had the lowest sand dune during this time period?
4. Which of the profiles had the widest horizontal extent of sand dunes? Approximately how
wide were they?
5. During which of the time periods were the sand dunes the most reduced in elevation?
6. Why were the dunes reduced? Provide some explanation about where this sediment may
have gone.
7. During which time period did the greatest amount of erosion take place on the island relative
to the baseline survey date of February 1, 2008. Explain why you think that this erosion took
place.
8. For each survey transect location (1-3) indicate where along the transect the most significant
erosion take place during the three survey dates. For example did the most amount of
erosion on transect 1 take place at the beach face or in the dunes between the first and third
survey?
9. Which of the 3 transects shows the greatest amount of net deposition in the dunes during the
post-Hurricane Alberto recovery time period?
10. Which of the profiles shows the greatest amount of net deposition in the intertidal zone
during the post-Hurricane Alberto recovery time period?