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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 Stake

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 monument.

volunteer using emery rod method
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.

dune and beach profile terms

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.)

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