The Texas High School Coastal Monitoring Program Field Procedures
Contents

This section contains detailed instructions for making the field measurements. Background material describing the purposes of the measurements is included.

Preparation for Field Work
Going to the Study Sites
Initial Site Reconnaissance
Beach Profile Measurement
Beach Sediment Samples
Process Measurements Global Positioning System Survey of the Shoreline and Vegetation Line
Photographs and Sketch

Preparation for Field Work

The following should be completed about two days before a scheduled field trip. You need a couple of days to remedy any problems you might discover.

  1. Check the tides, and try to time your beach surveys to occur at low tide if possible.
  2. Determine who will go on the trip, get permission slips as needed, and arrange transportation.
  3. Check the weather forecast.
  4. Check to make sure you have enough copies of field forms. You should have several extra copies.
  5. Check all batteries for charging. The GPS receiver and camera both require batteries to operate.
  6. Check all other equipment and place in equipment bags and in staging area ready to go for the trip. Use the equipment checklists below.

Emery beach profile equipment list

  1. Red and black Emery rods
  2. 30-meter tape measure
  3. Sediment sample jars (3 per profile plus 1 extra)
  4. Sighting compass
  5. Sighting level
  6. 5 long flags
  7. Small metal survey flags
  8. Clipboard
  9. Field book
  10. Data forms
  11. Permanent markers
  12. Hand lens

Shoreline and Processes Equipment

  1. GPS receiver with charged batteries
  2. Red and black Emery rods
  3. 50-meter tape measure
  4. Zip lock freezer bags
  5. Sighting compass
  6. Sighting level
  7. Wind gauge
  8. Digital camera
  9. Small metal survey flags
  10. Clipboard
  11. Field book
  12. Data forms
  13. Permanent markers
  14. Hand lens
  15. 3 floats (rubber or plastic balls about the size of baseballs that one can throw at least 30 m)
Going to the Study Sites

On the day of the trip you should make a quick check to make sure everything is taken from the staging area and has been loaded in the vehicle. Drive to the study site, park safely and well off the side of the road. Stay on the side of the vehicle away from the road. Find the datum point using the GPS receiver and compass or earlier placed markings. Place a flag at the datum point so it is visible above the grass.

Initial Site Reconnaissance

Sometimes we get so involved in making our measurements that we fail to use our qualitative power of observation. Taking time to walk the beach without the worry of having to take an accurate measurement will help you interpret the quantitative data you collect.

Before you start measurements take about 15 minutes to walk the profile and observe the condition of the beach. Identify the prominent features of the profile including the foredune, vegetation line, wet/dry line, berm crests, and cusps. Do a little beach combing and see if there are any prominent or unusual items such as dead fish or seaweed on the beach. Note how the beach has changed since your last visit. Does it appear to have eroded or accreted? Have there been human alterations?

Beach Profile Measurement

A beach profile is a topographic transect measured perpendicular to the shoreline. This is the primary measurement to make. If you do not have time to make all the measurements described below, this should be the first thing you do. Having an accurate time series of beach profile measurements is essential for deciphering shoreline erosion and accretion trends and tracking beach recovery after storms.

You will measure beach profiles using the Emery technique, named after the person who applied this topographic measurement method to beach studies. It is simple and "low-tech" but accurate. Papers on beaches that have used this technique have been published in scientific journals. A very important note of caution, however, is required. If a measurement error is made at one point, then all subsequent points along the profile will be offset by that amount of error. Therefore, take your time and double check each reading. It is very disappointing to realize after returning from the field that your hard-earned data are erroneous.

  1. Mark profile with stakes or flags - Flags will help the surveyors stay along a consistently oriented traverse. Two people are needed for this task. See the figure that illustrates this process.
    1. One person goes to the foredune crest or other point from which the entire profile is in view. Using a sighting compass, site back to the datum and move left or right until the correct azimuth is obtained (when sighting landward, the azimuth will actually be the reciprocal (180 degrees difference) of the value listed as the azimuth). Place a stake or flag at this location.
    2. Standing on this point, have a team member with a stake or flag move about half way between you and the datum point. Line this person up so that they are on the profile (between you and the datum point). Have them place another stake or flag. The landward portion of the profile is now marked.
    3. Still standing on the same point determined in (a), turn 180 degrees and, with the compass, site toward the water in the direction of the proper azimuth for the profile. Have a team member go to the wet/dry line (The wet/dry line is the landward most limit of sand wetted by ocean water, not rain). Direct the team member to move left or right until they are on the profile. Have them place a stake or flag at this point.
    4. Now have the team member move toward you along the profile. Line them up on the profile. Have them place a stake or flag at the vegetation line (seaward extent of vegetation).
    5. Place other flags along the profile at all bermcrests, the last high-tide swash line (often delineated by a line of debris or wet/dry boundary), edges of beach roads, and other features you want to be sure you measure during the profile survey.

      Note: If one can view the entire profile from the water's edge, fewer stakes will be required. This will be the case when surveying a profile without a prominent foredune. The idea is to place markers so that at least 2 of them are visible behind or in front of the suveyors when conducting the topographic survey.

  2. Conduct topographic survey (profile) - After marking the profile line, you are ready to measure distances and heights along the profile. At least two people are needed for this task, but these instructions are for five people. Having five people will increase accuracy, and allow for better observations and data recording. See the figure that illustrates this process.
      Team members:
    • Back rod (red) - This person sites and reads the rods.
    • Back rod assistant - Responsible for keeping the back rod vertical and measuring the distance between the rods.
    • Front rod (black) - One person on seaward rod (black). Holds rod vertical and picks the survey points.
    • Data recorder - One person is the data recorder.
    • Observer - Takes sediment samples and calls out observations to the recorder including geomorphic features, vegetation, sediment type etc.
    1. Start at the datum point. The top of the datum point is point #1 and is always dx=0, dz=0, the second point is the ground surface above or below the datum point. At this point, dx is always 0, and dz is the distance above or below the top of the datum point. Use your tape measure to measure dz for point #2.

      Note - The Emery rods are marked in 2-centimeter increments. The numbers are on top of the line that they label. Read the rods to the nearest centimeter.

    2. The back rod (red) is now placed on point #2 (next to datum point) and the front rod (black) moves seaward along the profile to the 3rd survey point. Use the earlier placed markers to line yourself up on the profile line. Refer to diagrams here if you haven't already!

      Note - The maximum distance between the rods should be about 5 meters. Shorter distances should be measured where there is a change in the slope of the ground or some other key feature such as the vegetation line.

      Hold the rods steady and vertical. Use the bullseye levels on top of the rods to aid holding them vertically. It is important for the assistant on the back rod (red) to aid keeping the rod vertical when the other surveyor sites along the rods to determine vertical change.

      If the front rod (black) is lower than the back rod (red) then the back rod holder draws an imaginary line between the horizon and the top of the front rod. Where that imaginary line intersects the back rod (red), read the number and record as negative in the dz column.

      If the front rod is higher than the back rod (red), then the back rod holder draws an imaginary line between the horizon and the top of the back rod (red). Where that imaginary line intersects the front rod (black), read off the number on the black rod and record as positive in the dx column.

      Note - If the horizon is not visible because of low visibility or an obstruction, use the sighting level instead.

      Measure the horizontal distance between the two rods while the observer or recorder helps keep the tape horizontal. Record this distance in the dx column in centimeters.

      Record observations (vegetation, geomorphology, sediment) in the notes column about the black rod location.

      If the front rod (black) is on a point where a sediment sample is to be taken, first record dx and dz then stop and take the sample next to the front rod. Record in the notes column the sample number. See the sediment samples instruction sheet for details on taking a sample and labeling it.

      If the front rod (black) is at the still water line, record this in the notes column along with the time.

    3. Front rod (black) stays in place to mark the spot until the back rod (red) holder moves up to the exact same spot. Only then does the black rod holder move up to the next survey point. Repeat step (b).

      Using the sighting level.
      Using the sighting level
      Using the horizon for the level line.
      Using the sighting level
      Marking the profile.
      Marking the profile
      Reading Emery Rods
      Reading emery rods
Beach Sediment Samples

Geologic setting and physical and biological processes control sediment grain size and type. Geologic setting refers to the geomorphology of the terrain and the type of sediment or rock on which the beach is formed. In some cases, a topographically low, eroding, muddy marsh may be the platform on which the beach is formed in others an earlier established sandy barrier island or a bedrock ledge may be the setting. Physical processes refer to the action of waves, tides, and wind as they move sediment on the beach. Biological processes are those associated with plants and animals. Plants and animals may be sediment producers for the beach, especially shell producing animals, but they also affect sediments by their burrowing and their baffling of wind and wave energy.

Grain size and type analyses of three sediment samples taken along the beach profile will typically reveal the different processes at work. Comparison of samples over time and among different beaches will provide additional insight to how beaches respond to varying conditions. At each location, you will take a core of sediment about 5 cm long that will represent conditions over some period of time. Given the frequency of your sampling (every 2 to 4 months), analyses on a core of sediment will provide more reliable data than just scraping the surface of the beach, which would often just represent the last few moments of deposition or erosion.

  1. Take one sand sample from the foredune, berm top, and beachface areas (see the figure).
    Samples from the foredune, bermtop, and beachface areas.
  2. Take the samples during the measurement of the beach profile along the profile line. Note on the beach profile form the point at which you take the samples.
  3. Write the following information on the sample cup before taking the sample. Use a permanent marker. Profile name: e.g. BEG02
    Sample location: foredune (FD), berm top (TB), or beachface (BF)
    Date (year/month/day) and time: e.g. 1997/09/23 0830
    Sample number: e.g. BEG08-BF-19970923-0830
    Label the sample container with appropriate information. Taking the sample.
  4. Pick an undisturbed area and push a small plastic sample cup into the sand. Carefully pull the cup out while holding the sand in it and place the lid on it.
Process Measurements

Tracking the topography of the beach shows us how the beach changes, but measuring the wind and waves will help us to understand why the beach changes. The process measurements you make during your beach visits are just a snapshot of what is going on in terms of wind, waves, and currents. What is really pertinent to the state in which you find the beach, however, is what was happening for some period of time (hours to months) before your arrival. Unless you obtained process measurements every day, you will not be able to collect enough data to properly relate your measurements to your beach profiles. Fortunately there are many areas where instruments are acquiring hourly data on wind and waves.

The National Oceanic and Atmospheric Administration (NOAA) operates weather, current, and wave stations around the U.S. coast. These stations, however, will not likely be at your beach profile location, but you can use the measurements you make to determine the differences in measurements between your location and the continuously operated stations. After you have enough simultaneous measurements, you will be able to "calibrate" the continuous data for your beach location. For example, if your wave height measurements are consistently higher than those obtained by an offshore gauge you will know to increase the wave height measurements at the offshore gauge before applying the data to your beach location. Similarly if the wind direction at a weather station is consistently more out of the north than at your location or the speed is higher, then you know how to correct these data for your location.

There is another reason to make careful measurements of the processes. This is simply to hone your powers of observation and to increase your appreciation of the physical processes shaping the beach environment. The techniques here are qualitative, therefore, 3 people will make estimates to provide more reliable data. Following are the methods to employ.

  1. Wind direction and speed
    1. Go to a high point in the area of the beach profiles. The foredune crest (location 7 in the diagram) or on top of a seawall would do fine. Make sure you are not shielded from the wind in any direction.
    2. Face directly into the wind by feeling it on your face. Without moving your head, raise the sighting compass and determine the bearing pointing into the wind. Record this magnetic bearing.
    3. Face directly into the wind and hold the Dwyer wind meter to the wind. Hold the meter upright with the two holes on the bottom directly into the wind. Read the level at which the ball is suspended. If the ball is at the top, place your forefinger over the top hole and read from the high-range scale. Maneuver the meter so that the highest readings are obtained. This is how you know if you have it pointed directly into the wind.
    4. Watch the meter for about 1 minute and determine the sustained wind speed. The sustained wind speed does not include sudden gusts or short calm periods of wind.
    5. Determine and record the highest wind gust speed during this time.
  2. Wave Direction
    1. From the same point that you determined the wind direction and speed (location 7 in the diagram), now determine the direction from which the waves are coming.
    2. Look across the breaker zone and focus on the waves where they first break. Turn your head so that you are looking directly into the oncoming waves. Raise your sighting compass and determine the bearing directly into the waves. Record this magnetic bearing. When sighting on the breakers, you may find it helpful to align the horizontal edge of the compass so that it is parallel to the breaker line.

    3. It is important to focus on the waves where they first break offshore and not on the waves near the beach.
    4. Keep your wave direction measurement secret and pass the sighting compass to the second and then the third observer for their determinations.
    5. All observers should record their observation in the place that corresponds with their observer number as written on the top of the form.
  3. Wave breaking height
    1. Move to the waterline and estimate the height of the breaking waves when they first break offshore (location 8 in the diagram). Moving to the waterline gives you a better perspective for estimating height. You will be nearly on the same level of the waves.
    2. Record your estimate in centimeters on the data form. Be sure to record in the location that corresponds with your observer number at the top of the data form.
    3. Keep your estimate secret and pass the form to the next observer.
  4. Wave period
    1. Focus on an imaginary point in the middle of the surf zone. You will count the waves passing this unmoving point for 10 seconds.
    2. As the crest of a wave passes your point count that as zero and start your stopwatch. The next wave is wave number one.
    3. When the 10th wave passes your point, stop the watch.
    4. Divide the number of seconds by 10 to get the wave period. Don't forget to convert minutes of time to seconds before you divide.
    5. Record your estimate in seconds on the data form. Be sure to record in the location that corresponds with your observer number at the top of the data form.
    6. Keep your estimate secret and pass the form to the next observer.
  5. Surfzone Width
    1. While standing at the waterline, estimate the width of the surf zone. This is the distance from the waterline out to where the waves first break. Record your estimate in meters on the data form. As with the period and height measurements, be sure to record in the location that corresponds with your observer number at the top of the data form. You should also consider that most people tend to underestimate distances across water.
    2. Keep your estimate secret and pass the form to the next observer.
  6. Number of longshore bars
    1. Estimate the number of apparent longshore bars by counting the number of breaker lines or visible shallow zones oriented parallel to the beach. As with the period and height measurements, be sure to record in the location that corresponds with your observer number at the top of the data form.
    2. Keep your estimate secret and pass the form to the next observer.
  7. Wave Breaker Type - Waves break in different ways depending on the wavelength, wave height, and slope of the surf zone. When the crest of waves curl and suddenly collapse, they are said to be "plunging". These are the types of waves surfers crave. When the crest continuously breaks as the wave moves on shore, it is said to be spilling. Surging waves push up the shore and slosh onto the beach without an orderly breaking of the crest. Surging breakers are rare, and along the Texas coast, generally will only occur where seawalls are in the surf zone.
    1. Observe the outer most breakers and record the breaker type as plunging, spilling, or surging. Make sure you record the outer most breaker type. Along shorelines with nearshore bars, spilling type breakers will almost always be present inshore of the outer breakers so don't confuse these breakers with what is occurring where the waves first break. There is often a mixture of plunging and spilling types, but you must decide which is the dominant type and check only one on the form.
  8. Longshore Current - The longshore current is the movement of water along the shoreline and is caused by (1) waves approaching at an angle to the shoreline, (2) tidal currents, and (3) wind. You will measure the speed and direction of the current using a float that you throw into the surf zone.
    1. You need a float that you can throw at least 30 m and that has a low profile to the wind when it is in the water. A low profile is important because our intent is to measure the water current, not the wind direction and speed. A rubber or hard plastic ball about the size of a baseball and that has some weight to it makes a good float. You also need a stopwatch.
    2. Go to the water line and throw the float into the middle of the surf zone or as far as you can if you can not reach the mid surf zone.
    3. Step back up the beach and, with your heel, mark a line in the sand at the position of the ball and start the stopwatch.
    4. Walk along the beach following the ball as it moves along the shore. Do not take your eyes off the ball. When 50 seconds have passed, mark another line in the sand.
    5. Record the distance from the waterline you initially threw the float. This is useful information because your results may vary with this distance.
    6. Measure in meters the distance the ball moved along the beach.
    7. Multiplying the distance by 2 gives the speed of the longshore current in centimeters per second. Record the speed and direction the float moved on the form.
    8. Repeat (b) through (g) two more times.
      Measuring foredune orientation
      Measuring foredune orientation
      Measuring foredune orientation
  1. Survey at least 200 m of the shoreline with the GPS receiver.
  2. Survey at least 200 m of the vegetation line with the GPS receiver.
  3. Take photograph looking along the berm crest or wet/dry line.
  4. Take photograph looking along the dune crest.
  5. Take photograph looking along the berm crest or wet/dry line.
  6. Take photograph looking along the dune crest.
  7. Determine wave direction, and wind direction and speed from highest point on profile, count number of longshore bars, measure foredune crest orientation.
  8. Estimate height of breaking waves, measure wave period and longshore current.
  9. Measure beach cusps and berm crest or wet/dry line orientation.
Global Positioning System (GPS) Survey of the Shoreline and Vegetation Line

Beach profiles provide detailed topographic information for analyzing morphology and sediment volume. These profiles, however, cross the shoreline and vegetation line at just one point. GPS surveys provide continuous data alongshore. Measured shorelines and vegetation lines from different times can be plotted on the same map for comparison. This is how the rate of shoreline change is typically determined along a coast.

The shoreline for the purpose of this study is defined as the wet/dry line. The wet/dry line is the landward most limit of sand wetted by ocean water (not rain). This roughly corresponds to the position of high tide on the beach and is identified by a tonal contrast. The vegetation line is the seaward extent of vegetation. The vegetation line is measured because it is an important legal and physical boundary. In Texas, houses and buildings must remain landward of the vegetation line. Vegetation is also required for the natural growth and maintenance of protective foredunes.

You will use a real-time differential GPS (DGPS) receiver to conduct the survey. The GPS receiver uses transmissions from satellites to determine latitude and longitude. A GPS receiver operating alone can determine positions accurate to about 100 m. When a second receiver, however, is operated simultaneously and remains in a known location, data from it can be used to correct the position of another receiver in the area that is moving. This is called differential GPS, and it can provide accuracy of a few meters. Your real-time DGPS receiver is receiving data from the satellites to calculate latitude and longitude while at the same time it is receiving data from a nearby receiver operated by the U.S. Coast Guard. Your receiver uses the data from the U.S. Coast Guard to correct its computed position immediately or in other words in "real time."

  1. Before beginning the GPS survey, you or other members of your group should mark the profile location with flags. Flags should be placed on the vegetation line and the wet/dry line (shoreline) along the profile. Using a measuring tape or by pacing, place flags 100 m to each side of the profile along the shoreline. These flags mark the extent of the GPS survey.
  2. Stand on the southwest, west, or northwest end of the wet/dry line (shoreline). Consult the instructions for your GPS receiver on the following pages and turn it on. Record the latitude and longitude of this location and the time on the data form.
  3. Walk along the wet/dry line toward the other end of the survey area while the receiver is automatically recording data. If the receiver is set correctly, you should see your path plotted on the screen.
  4. Because of the small variations in beach topography and the way waves rush up the beach, the wet/dry line will have curves in it. It is not necessary to follow every curve. Instead, walk a relatively straight line that is an average of these curves. Do not stray from your line or you will have extraneous points in your recorded file. Do not stop for long periods of time or your GPS receiver may run out of memory.
  5. When you reach the flag on the other end of the survey area, proceed directly up the beach to the vegetation line without changing the receiver. Start walking back along the average vegetation line.
  6. When you arrive at the end where you started, proceed directly down the beach to the flag at the wet/dry line. Record the latitude and longitude of this location and the time on the data form.
Photographs and Sketch
  1. Digital Photographs - Photographs provide a qualitative record of the state of the beach. Taking them from the same vantage point each time will increase their value for interpreting beach changes. You will take five "official" photographs. A common mistake in taking these photographs is to include too much sky in the frame. You should only have about of the frame filled by the sky.
    1. Walk 50 m to the side of the profile. From the wet/dry line, take a photo along the beach looking back toward the profile. Be sure to include some of the surf zone in the photo and the vegetation line if you can. Walk up to the foredune crest and take a photo looking back toward the profile.
    2. Take the same photographs from the other side of the profile.
    3. Take the 5th "official" photograph looking up the profile line from the waterline.
    4. Go ahead and take additional photos of other interesting features on the beach and of your classmates. Note on the sketch page the photographs you take, and if necessary, explanatory notes of why you took the photograph.
  2. Sketch - This is an optional exercise, but if you have the time to do it you should at least try. When one starts drawing an object or landscape, one often notices things not noticed before. A sketch of the beach will also help interpret the quantitative data and photographs you collect. It need not be a "work of art" to be useful, as you can see in the example on the following page.
    1. Walk 50 m from the profile to the right of the profile as one faces seaward. Your vantage point for the drawing will be from above the beach and over the water. Of course you cannot go to this point so you will have to imagine yourself looking down on the beach from that point while you draw.
    2. On the data form with the grid, draw the foredune crest line or vegetation line along the left side of the paper and sloping up and to the right. If there are breaks in the foredune such as blowouts, washover fans, or walkways, include them in your drawing.
    3. Next draw the profile line perpendicular to the foredune line. Label the starting point and the ending point at the waterline. This profile line should show the shape (topography) of the beach with the berm tops, berm crests, and beach faces evident. The distances between these features should be proportional.
    4. Now draw lines along the beach that represent the vegetation line, scarps, berm crests, cusps, and wet/dry line.
    5. Fill in the drawing with observations of such things as deposits of shells, debris, or any other items or beach features. This is also a good place to document human alteration of the beach such as dune fencing, planting of dune vegetation, or bulldozing of the beach.
  3. Example of a beach sketch
    Example of a beach sketch