1. The Effect of Seawall Construction on the Coastline
Ben McGinnis
GLY 558 – Introduction to Coastal Management

2. Seawalls, Bulkheads, and Revetments
Seawalls are usually massive, vertical structures used to protect backshore areas from heavy wave action
Bulkheads are large vertical retaining walls used to reduce loss of land to the sea and to protect backshore areas from wave action
Revetments are shoreline structures generally sloped in such a way as to mimic the natural slope of the shoreline profile and dissipate wave energy as the wave is directed up the slope

3. Why don’t they work? Lacks the flexibility of a dune system
A change in beach slope is not allowed
Longshore currents scour sand from the base of the seawall
Loss of sand from reflected wave energy

4. Wave Energy Dissipates over the surface of a natural beach
Seawalls reflect wave energy
Reflected wave energy stirs up the sand and washes it out to sea

5. Sandbridge Beach, Virginia
Bulkheading began around 1988
Primarily Steel
Beach has narrowed and flattened
Rebuilt bulkheads
Old bulkheads in surfzone
Beach nourishment 1998 and 2002

6. Interesting Points from: The Beaches are Moving: The Drowning of America’s Shoreline Kaufman, W., and Pilkey, O.H., 1983
No erosion problem exists on beaches until people build on them.
Anything built along the coast increases erosion rates due to the lack of flexibility in the beach system.
Once beach protection is started it’s can’t be stopped.
To “save” the beach, we must destroy it.
The cost to save property is greater than the value of the property.

7. Seawalls are constructed to protect beachfront homes, but how can you have a beachfront home when there is no beach?