Mitigation Through Surf Enhancement/Introduction
|Mitigation Through Surf Enhancement|
An Early History of Pratte's Reef
Over the last 40 years countless surf breaks have been altered or destroyed as a result of coastal development in California. One of the more famous cases was the destruction of a renowned Southern California surfing locale, "Killer Dana", by a large system of jetties that were constructed to create Dana Point Harbor. Historically, coastal managers, in their efforts to stabilize the coast and ward off erosion hazards, have ignored surfers and surf breaks. However, with increased numbers and organizations such as the Surfrider Foundation, the surfers are making their argument heard.
After 10 years of controversy surrounding the construction of a groin in El Segundo and the following degradation of local surfing conditions, Surfrider Foundation, the California Coastal Commission and Chevron Corporation - El Segundo announced a collaboration to enhance surfing near the El Segundo groin (Ewing, 1995). Through the installation of an artificial surfing the reef, the triumvirate intends to restore the quality of surfing in the area. This case is important for a number of reasons and demonstrates both strengths and weakness in the permitting system in California. By agreeing that restoration of the surf is a compensatory resolution for construction of the groin, the California Coastal Commission is recognizing surf as a natural resource with recreational potential worth preserving. In El Segundo the degraded surf is to be enhanced by the installation of an artificial surfing reef. Surf enhancement or creation of "surfable" waves by an artificial reef is an untested science so the outcome of the project is unpredictable. The success of the artificial reef may have implications for future management practices.
Thousands of shoreline engineering structures have been installed along the coasts of the world in an attempt to interrupt the littoral flow of sand, thereby slowing erosion of the beach on the "upstream" side of the structure or allowing safe entry into a harbor. By the very nature of their construction objective, shoreline engineering structures alter the nearshore beach face. As waves propagate shoreward their breaking shape and geometry are related to the shallow water bathymetry (Galvin, 1972), thus alterations of the beach will affect the waves breaking on that beach. In many cases engineering structures can have a positive effect on surfing near these structures. A good example of a surfing area enhanced by an engineering structure is the Wedge in Newport Beach, CA. Owing to wave reflection off the Newport Harbor jetty, waves at the Wedge double in height and provide a spectacular setting for body surfing. However, these structures can also have negative effects on surfing conditions, as seen in Dana Point and El Segundo. The El Segundo situation is unique because another shoreline engineering structure, the artificial reef, will be installed to enhance the surf altered by the groin.
The reef will be comprised of large geotextile bags filled with clean sand. The volume of the artificial reef will be approximately 600 cubic meters with sides that are approximately 50 meters long. Depending on deployment method, the size of the bags will range from about 3 cubic yards (4 tons) to 10 cubic yards (15 tons). The geotextile bags are advantageous because the reef can easily be expanded or removed dependent on the success of the project.
While analogous to a submerged breakwater, which has a long design history, the intended surfing effects are a new objective. Because no other engineering structures have been created to enhance or create surf in a natural setting, modeling may help predict important design parameters. In order to design an artificial reef that will enhance the surf in El Segundo and create "surfable" waves, preliminary computer modeling will investigate reef designs and locations. Modeling reef designs under differing wave climates will help test the sensitivity of the parameters involved in creating a "surfable" wave. The model involves the following nearshore wave parameters: wave height, wave period, wave direction. The reef design parameters are volume, reef height, the angle of the nose, the toe angle, and the inshore location. By investigating the "typical" wave climates that should produce "ridable" surf in El Segundo and modeling these conditions with multiple reef designs, the roles of important parameters will be investigated.
The success or failure of the artificial reef has interesting implications to the evaluation of coastal management decisions made by the Coastal Commission. If the reef is considered a success and surf is restored to El Segundo, it suggests that the Coastal Commission has successfully balanced development and public interests. The success of the artificial reef may justify increased coastal alterations or it may prove to a be a less intrusive way to ward off hazardous coastal conditions. Failure of the artificial reef may rekindle the coastal management debate in El Segundo, forcing decision makers to reevaluate the equity behind sacrificing local surf conditions for the protection of coastal dependent facilities. The future of surf as a natural resource may be foreshadowed by the creation of the first artificial surfing reef.