Gran Domicus Hotel, Punta Cana, Dominican Republic

 

 

 

FRONT PAGE

 

INTRODUCTION

 

OBJECTIVES

 

METHODS OF ANALYSIS

 

HARBORING-AQUATIC-LIFE ARTIFICIAL REEFS

 

WAVE-BREAKING ARTIFICIAL REEFS

 

CONCLUSIONS

 

REFERENCES

Background on the Gran Domicus Hotel:

 

          The Gran Domicus Hotel is located on the eastern shore of the Dominican Republic in a city called Punta Cana.  The Dominican Republic is an island in the Caribbean Sea, and it shares its island with Haiti.  A localized map is shown here.

 

          The Gran Domicus Hotel was scheduled to open in 1998.  For this hotel to be successful, it needed a large, expansive beach.  The natural beach was rocky, with sand beginning a few meters beyond the surf.  Plans to fortify the beach with new sand, however, had failed, as the sand was transported away by wave-breaking action on the beach.  The Gran Domicus Hotel, seeing no other plausible option, turned towards wave-breaking artificial reefs to help sand accumulate on its shores. 

 

 

Placing the wave-breaking artificial reef:

 

          The Gran Domicus Hotel decided on a three-tiered wave-breaking artificial reef, consisting of Reefballs™.    Reefballs™ are reinforced concrete, hemispherical structures that are designed to break waves before they reach the shore.  A picture of a reefball can be seen here.

 

          The Gran Domicus design had about 500 Reefballs™ placed in three rows, 150 feet offshore. 

 

 

Success of the Reefball™ project:

 

          The Reefball™ project at the Gran Domicus Hotel was a great success.  The Reefballs™ not only stopped erosion from occurring, they actually added a substantial amount of usable beach area.  From 1999 to 2001, the Gran Domicus beach has gained over 10 meters of shoreline.  Below is a profile view of the Gran Domicus Hotel shoreline:

                       

 

                   Figure 1:  A profile of the beach at the Gran Domicus Hotel in Punta Cana, Domincian Republic.  The dashed

                               line is the beach profile in February of 1999.  The solid line is the beach profile in April of 2001.

 

 

So what is 10 meters of new beach?  It doesn’t sound like much.  However, the pictures lead one to think otherwise:

 

                                                                                                    

                                                                                     BEFORE:

 

                                                   

 

                                                 Figure 2: The beach at the Gran Domicus before the Reefballs™

                                                                                        were placed.

 

 

                                                                      AFTER:

 

                                                  

 

                                                  Figure 3:  The beach at the Gran Domicus after the Reefballs™

                                                                                        were placed.

 

Analysis of Gran Domicus Hotel beach:

 

          The Gran Domicus Hotel Reefball™ project is a prime example of what can happen when a wave-breaking artificial reef is placed offshore.  As the waves approach the shore, an effect called shoaling, the wave increases in height with respect to the depth of the water.  The H/D ratio becomes larger as the wave moves towards shore.  If the H/D ratio exceeds 0.73, the wave will begin to break.  In the case of the Gran Domicus Hotel, the bathymetry (or topography under water) is such that the waves break right as they hit the shore.

 

          With the wave-breaking artificial reef offshore, however, shoaling occurs much sooner.  As the waves travel over the artificial reef, the water depth is decreased, thus increasing the H/D ratio.  If designed properly, the wave-breaking artificial reef will induce shoaling to such an extent that the H/D ratio will exceed 0.73, and the waves will break over the reef.  Once the waves break, the wave energy dissipates over the reef, leaving smaller waves to travel to the shore.  Once at the shore, the waves will only break a small amount, as the height of the wave is comparatively much smaller than the original wave would have been.  This lower wave height and lower breaking energy helps keep the sediment from being resuspended.  If not resuspended, the sediment will have a chance to accumulate on the newly protected beach. 

 

 

Stability of Reefballs™:

 

          The question of stability has been raised when talking about any Reefball™ project.  The Gran Domicus Hotel project was no different.  There were concerns that the Reefballs™ would be washed away during a large storm event, such as a hurricane.  Being located in the heart of a hurricane zone, the Gran Domicus planners had reason for concern.  One month after being placed, Hurricane George hit the Dominican Republic.  About 100 Reefballs™ were washed out to sea, leaving about 400 remaining.  This problem is inherent in the design of the Reefball™.  Its large surface area and relatively small weight will always give the Reefball™ problems with placement.  Perhaps anchoring them to the ocean floor would provide more stability.