El Segundo, California, U.S.A.

 

 

 

FRONT PAGE

 

INTRODUCTION

 

OBJECTIVES

 

METHODS OF ANALYSIS

 

HARBORING-AQUATIC-LIFE ARTIFICIAL REEFS

 

WAVE-BREAKING ARTIFICIAL REEFS

 

CONCLUSIONS

 

RECOMMENDATIONS

 

ACKNOWLEDGEMENTS

 

REFERENCES

Background on El Segundo, CA:

 

          El Segundo is a nearby suburb of Los Angeles, located in Southern California.  A map of El Segundo is shown below:

 

                                                  

 

The Channel Islands are about 25 miles offshore, located to the north and to the south of El Segundo.  These islands have a great effect on the waves that approach the El Segundo shoreline.  Through diffraction and shadowing off the Channel Islands, the waves approaching the El Segundo beach are nearly normal to the shoreline. 

 

          Similar to the Gran Domicus Hotel in the Dominican Republic, El Segundo, CA, has had problems with beach erosion.  These problems have been addressed by a company named the Surfrider Foundation.  Through their research, they have devised a wave-breaking artificial reef that is, they hope, capable of protecting the El Segundo shoreline. 

 

                                                               

 

                                     Just like the Gran Domicus Reefball™ example shown above, the El Segundo

                                     reef project hopes to protect the shoreline through the use of an artificial reef. 

 

As seen in this picture, the waves break over the reef in an offshore area where they normally would not.  Notice the wave line breaking over the reef, but not breaking                                            where the reef is not present.  This is the effect both the Gran Domicus Hotel and El Segundo beach are looking for.

 

 

 

Final design of artificial reef:

 

          The Surfrider Foundation has come up with a final design for their wave-breaking artificial reef.  The reef design is unique to this project, and if successful, may set a precedent for future designs of wave-breaking artificial reefs.  The final design is shown below:

 

                                                                  

 

                                                                 The Surfrider Foundation’s final reef design.

 

         As the waves pass over the reef, they will break (due to the H/D ratio becoming larger than 0.73), and they will dissipate a lot of their energy over the reef.  As a result, the waves behind the reef will be much calmer than if the reef were not there.  Notice the relatively small size of the reef compared to the Gran Domicus example.  As the waves break over the reef, they are split by the triangular shape.  A schematic is shown below:

 

                                                           

 

                                                                  The waves split as they shoal over the reef.

 

          As the wave splits, it travels at an angle f/2 (with respect to normal to the waves) away from the reef.  The waves will continue to propogate outwards away from the reef at that angle until they are gradually changed by the bathymetry in a process called refraction.  Since the waves are propogating outwards, there will be a large area behind the reef that will be calm, thus helping to keep sediment on the beach rather than being resuspended.

 

         

Analysis of artificial reef off the coast of El Segundo:

 

          Since no date has been set for the placement of the El Segundo artificial reef, I had to rely on computer models to help provide some analysis for the wave-breaking potential.  Several parameters were looked at in the design with respect to wave height, such as toe angle (angle the reef makes with the bottom bathymetry) and the reef’s position relative to the shoreline (click on the links below to look at the parameters more in-depth).

 

1)      TOE ANGLE

2)      REEF POSITION

 

          As mentioned in each of the above links, the Surfrider Foundation will most likely chose a toe angle between 70 and 75 degrees with the horizontal, and a position that, combined with the correct reef height, will produce breaking waves over the reef.  No tentative date has been set for the placement of this wave-breaking artificial reef.