Photo: Rebuilding after Hurricane Sandy, U.S. Fish and Wildlife Service partners with the Nature Conservancy to erect “sand castle” barriers on Gandy’s Beach to protect Delaware Bay oyster beds from coastal erosion. Credit: Adrianna Zito-Livingston/The Nature Conservancy

Procedure

Safety Note: If using an electrical device to generate waves, keep the device far away from the water. Promptly clean up splashes to prevent slipping. Consider doing the wave tank part of this activity outside if the weather permits.

A. The Scenario
Your group is a coastal management engineering firm. You are competing with the other groups in your class for a contract from a town called Seaside. Over the past few years, Seaside’s sandy beaches have been eroding. You must develop a plan to help the town manage its erosion problem. Your plan must include modifying the beach in some way to address immediate erosion concerns. Your plan must also include at least two policies that do not physically alter the shoreline, but instead regulate human behavior.

Each of the major stakeholders (groups of people with an interest in the issue of coastal erosion) in town will vote on your idea. In order to win the contract, you must balance their competing interests. Your teacher may also give you additional criteria to consider, such as a specific budget or other feasibility constraints.

Have a class discussion to come up with the criteria for determining the effectiveness of your engineering plan on controlling beach erosion, a concern of all of the stakeholders. The following are some erosion criteria to consider. Come to a class consensus on which of these criteria you will measure and how you will measure it. You may come up with criteria that are not on this list.

1. The height of the coastline
2. The width of the coastline
3. The overall shape of the coastline
4. The amount of sand pulled out to sea
5. How far up the shore the waves reach

B. Set up standardized wave tanks

You will use a wave tank to develop and refine your coastal management strategies.

1. (Optional) Wash the sand and rocks before the activity to remove fine particles that will make the water in your tank muddy.
2. Fill the tank with water to about one-third full. The height of the water should be the same among all groups.
3. Practice generating waves with a wind source or by displacing water using a paddle or other object. All groups should generate waves using the same method, they should have similar amplitudes and frequencies. Consider using a metronome to standardize wave frequency.
4. Create a beach by carefully pouring sand into one end of the tank, so that a portion of the sand extends above the waterline. Standardize as many variables as possible, you may think of more than the following factors:
   1. The total amount of sand
   2. The height of the beach
   3. The width of the beach
   4. The location of the endangered crab habitat (mark with toothpicks)
   5. The number and location of the houses
5. (Optional) Collect baseline data as a class in one of the tanks. This represents what will occur if nothing were done to the beach.
   1. Mark the shoreline with toothpicks.
   2. Sketch profile and top views of your coastline before generating waves.
   3. Measure things that correspond to your class beach erosion criteria (e.g., beach width)
   4. (Optional) Take “before” pictures of the wave tank and shoreline.
   5. Generate waves for 5 minutes. Try to keep the waves consistent in amplitude and frequency.
   6. Observe the wave patterns that are created. Make sketches of the wave patterns.
   7. At the end of the trial, draw profile and top views of the coastline. To observe changes in the shoreline, compare the location of the current waterline with the location of the toothpicks, which represents the location of the waterline at the beginning of the investigation.
   8. Measure things that correspond to your class beach erosion criteria (e.g., beach width)
   9. (Optional) Take “after” pictures of the wave tank and shoreline.

Photo: Bridgeton, N.J., student displays a full shell bag, one of 15,000 to be used to protect the Gandy’s Bay oyster beds. The bags will be placed offshore to create a 4,000 “living breakwater.” See U.S. Fish & Wildlife Service article HERE.

C. Develop Your Management Plan—Shoreline Modifications

1. Choose a name for your coastal management engineering firm.
2. In your group, discuss your ideas for managing Seaside’s erosion problems. You might consider multiple approaches in your plan to alter the shoreline. The following are some things you might consider:
   1. Building hard structures (some examples are in Table 5.12)
   2. b. Stabilizing the shore with “soft” non-structural techniques, for example, importing or shifting sand or planting vegetation
3. Test your structural ideas in the wave tank following Part B Step 5. During this time while you are developing and improving solutions, you may choose not to follow all of the steps, or you may generate waves for less time than suggested.
4. Collect final “before” and “after” data on your design plan by following all of the steps in Part B Step 5. The data you collect will be used in your presentation to stakeholders.
5. When cleaning up, dry out the sand before storing it by spreading it out in a pan or on plastic tarps in the sun.
6. Analyze and interpret your data.
   1. Compare your “before” and “after” data. How did the shoreline change? How much did it change?
   2. (Optional) Compare your “after” date to the “baseline” data collected in Part B. How did your plan compare to “doing nothing”?
   3. (Optional) If you took “before” and “after” pictures, analyze them to determine the difference in beach area (e.g., in cm2).

D. Develop Your Management Plan—Policies

1. Based on your wave tank results, and applying what you know about human behavior, suggest two policies for Seaside to consider as part of your management plan.
   1. If your wave tank results show a weakness in your design, policies may be added to prevent that weakness from becoming a problem (e.g., not building in a certain area).
   2. Policies can also be used to help enforce an aspect of your plan that might not be desirable to all of the stakeholders. However, remember that if your policies are unrealistic, none of the stakeholders will vote for your idea.
2. The following are some policy ideas—be creative in coming up with your own!
   1. Relocating structures to areas further away from shore (managed retreat)
   2. Buying-back houses that are too close to the shoreline, destroying the houses and relocating the owners
   3. Setting construction set-back limits
   4. Placing signs on dunes to stop people from walking on them

E. Communicate your management plan

1. Plan with your group how you will present your design solution, including your policy suggestions, to the stakeholders.
   1. You will be given a set amount of time (e.g., 5 min) to present your design.
   2. Decide how you will present your idea: wave tank demonstration, computer presentation, flyers, etc.
   3. You may want to share your before and after pictures and make charts with your data.
2. Communicate your management plan to the Seaside stakeholders. Your teacher might represent all of the stakeholders, other adults or students might role-play a representative from each stakeholder group, or everyone in the class might each be assigned to a stakeholder group.
3. (Optional) Prepare a written engineering design proposal. Use this opportunity to refine your ideas, taking into account any feedback from the stakeholders.