CONCLUSIONS

CONCLUSIONS:

As mentioned in the objectives page, the focus of this research was to analyze wave-breaking artificial reefs and their effect on wave height at the shore.

Both the Gran Domicus Hotel example from Punta Cana, Dominican Republic, and the El Segundo beach reclamation project example in El Segundo, California have shown that artificial reefs are an effective device that can be used to break waves sooner. If waves break over the artificial reefs, the majority of their energy is spent on the reef, making for calmer waves approaching the shoreline. If the waves are calmer as they shoal, they will not resuspend as much sediment compared to a wave that breaks directly on the shoreline. This helps promote a sandy beach, one that can be enjoyed by tourists and locals alike.

Artificial reefs have a calming effect on the waves that overtop them. This calming effect can be seen in the general figure below:

Figure 1: The general effect of a wave-breaking artificial

reef [Yoshioka, 1993].

As the wave passes over the reef, the waves with a higher wave height break over the reef (i.e. the 2, 3, and 4 meter waves shown in the graph). This is due to the H/D (height of the wave compared to the water depth) ratio increasing as the wave passes over the reef. This induced shoaling effect results in many more waves that are 1 meter high or less.

In the case of the Gran Domicus Hotel in the Dominican Republic, the waves break over the three-tiered artificial reef breakwater made up of Reefballs ™. As the waves break over the reef, they lose much of their energy, leaving calm waters behind the reef. As shown in Figure 2, the Gran Domicus Hotel has added over 10 meters of shoreline in sediment accumulation in just over two years:

Figure 2: The artificial reef project at the Gran Domicus Hotel in Punta Cana, Dominican Republic has

resulted in a dramatic increase in the amount of beach available to tourists.

This artificial reef project is considered a major success for the Gran Domicus Hotel. I expect many more hotels to employ artificial reefs such as the Reefball™ artificial reef to help stop erosion and even accumulate more sand on their beaches.

In the case of the El Segundo beach reclamation project, the waves also are expected to break over the reef, leaving calm waters behind the reef. The major difference between the two projects is the size of the artificial reef. Since the El Segundo reef has a design that splits the waves and sends them at an angle away from the reef, the area calmed behind the reef is substantial. No large breakwater is necessary. Once again, this reef has not been placed yet, so I have relied on computer models generated by the Surfrider Foundation to help analyze the reef’s effect on wave height, such as the one shown in Figure 3:

Figure 3: The artificial reef project in El Segundo, California is expected to

have a large impact on the waves approaching the shore.

As shown in Figure 3, as the waves break over the reef, there is a sudden increase in the wave height. This is due to the waves reaching their maximum wave height as they shoal over the reef. But note as the waves propogate towards the shoreline after they have been broken over the reef, the wave height dramatically decreases. If successful, the El Segundo, CA reef project may open many doors for beach reclamation projects up and down the world’s coasts.

To find out more about the analysis of why each of these artificial reefs work, please click on the links below and go to the analysis portion of the page:

1) Gran Domicus Hotel, Punta Cana, Dominican Republic

2) El Segundo, California

CONCLUSIONS

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