F.  SHORELINE PROTECTION

       Because so many people live along shorelines, much effort
       has gone into protecting them from erosion.  These efforts
       include engineering structures (which have proven largely
       ineffective) and non-structural approaches (such as beach
       nourishment ).
 

       1.  SEAWALLS / REVETMENTS

            The purpose of seawalls or revetments is to protect coasts
            from erosion caused by direct wave attack.  However, the
            benefit is usually temporary, because waves will eventually
            undermine the structure (picture of undermined seawall).

       2.  BREAKWATERS

            Breakwaters protect harbors from wave action, creating
            a quiet water area where longshore drift can accumulate.
            In cases where longshore drift does accumulate, increased
            erosion is likely in the downcurrent direction.

       3.  GROINS / JETTIES

            Groins and jetties are used to trap longshore drift and thus
            widen or maintain a beach.  However, trapping sediments
            on one side of these structures leads to increased erosion 
            on the downcurrent side.  (See Ocean City, MD)
            
    

       4.  BEACH NOURISHMENT

            Beach nourishment is an attempt to balance the sediment 
            budget by adding sand to a beach.  Sources of sand include
            inland quarries and the dredging of areas where sand has
            accumulated (e.g., offshore or on the upcurrent side of an
            engineering structure).

            Miami Beach has managed to survive rising sea level only
            by periodically adding sand to its beach.  Other East Coast
            communities have tried the same approach, with varying
            degrees of success (e.g., Ocean City, NJ).

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