Beach and Dune Profiles:
An Educational Tool for Observing and Comparing
Dynamic Coastal Environments...continued
Beach and Dune Profiling How-tos
Setting the Permanent Monument and Profile
The most active and changing part of the dry beach
system is the area slightly landward of the foredune crest and seaward
to the surf zone (Figure C, bottom of page). As such, it is a good
place to conduct profiles. It is very important to establish a point
of reference -- a fixed point that can be easily relocated during
future visits -- in order to record seasonal and stormrelated changes.
NOTE: To ensure a reliable reference point, we recommend
installing a permanent monument in the back, stable area of the
dune (Figure C, bottom of page). A 6-foot long wooden stake, measuring
4 inches square, would serve as an inexpensive and simple permanent
Click here to view a larger
version of Figure B.
The next step in conducting an Emery Rod profile
is to install a profiling stake. Using this profiling method requires
that the horizon be visible. With the horizon in view, install a
profiling stake just landward of the foredune crest (Figures
B & C). A wooden stake or copper pipe can serve as a profiling
stake; it should be at least 5 feet long and driven into the dune
with approximately 1 foot of the stake exposed. This is the point
from which most profiles will begin.
NOTE: Only on the rare occasion that a portion of
the backdune has changed or if the profiling stake has been lost
(perhaps due to a major storm), will it be necessary to repeat the
profile from the permanent monument to the profiling stake location.
Obtaining Dune and Beach Elevations
Once the permanent monument and profiling stakes
have been established, it is time to record various elevations and
measurements. Recording this information is best done on a data
sheet. An example of a beach profile data sheet is included in Attachment
1. Some examples of measurements to be recorded include:
• the distance from the top of the permanent
monument or profiling stake to the sand surface
• the geographic coordinates of the monument and stake (using
a compass for triangulation* or GPS), and
• the compass bearing of the desired transect
*Triangulation is obtained by taking compass bearings
from your stake to three easily observable objects, such as a water
tank, transmission tower, or roof chimney, etc.
NOTE: Triangulation or GPS data will allow you to
easily relocate your markers and will allow you to plot your transect
locations on a topographic map, nautical chart, or orthophotograph.
Most likely, the horizon will not be visible from
the permanent monument. To obtain the backdune profile for the area
between the permanent monument and profile stake (Figure D, next
page), a standard surveying technique is required. One simple option
is to attach a sighting level to the top of the back rod. Looking
through the sighting level to the front rod, read the number on
the front rod. This number represents the dune elevation change
between the rods. An inexpensive sighting level can be purchased
at most hardware stores for approximately $20. Another simple method
is to string a taut line between the two vertical poles and suspend
a line level from the string. When the line is taut and level, read
the numbers from each rod where the line intersects the poles. The
difference in elevation between the rods, and thus the dune elevation
change between the poles, is the difference between the numbers
read from each rod.
Once the initial elevations have been recorded,
it is time to record data for the area seaward of the profiling
stake, where the horizon is visible (Figure B). For the first reading,
place the back Emery Rod against the profiling stake, making sure
the rods do not sink into the sand and that the rods are vertical.
A one-ounce fishing weight or plum-bob can be hung from the side
of the back stake with a cup hook to ensure that they are vertical.
Standing behind the landward rod, line up your eye with the top
of the lower of the two rods and the horizon (Figures B and C).
This imaginary line-of-sight will intersect one of the two rods.
Note the elevation number where the line-of-sight intersects the
rod. The difference represents the elevation change of the dune
or beach between the two rods. If the number came from the front
rod, the slope went up and should be recorded as a positive number.
If the number came from the back rod, the slope went down and should
be recorded as a negative (see example, Figure C). Always make sure
a plus or minus sign is recorded. (This technique is prone to cumulative
error. If one number is recorded incorrectly, then all subsequent
numbers for the profile will be affected.)
To obtain the next reading, move seaward and place
the back rod in the same location previously occupied by the front
rod, and repeat the line-ofsight step outlined in the previous paragraph.
Continue this sequence all the way to low water, or preferably to
wading depth to obtain as much of the profile as possible. (To capture
the profile of the winter or storm-derived sandbars, one would have
to go into the breaker zone or farther.)