Beach Erosion
Notes
Causes of Sand Depletion
•
Waves
•
Wind
•
Storms
Hurricanes & nor’easters cause
the most erosion.
Winter Beach
When storm waves carry
sand off & deposit it in
an offshore sandbar;
results in a very narrow
beach.
Summer Beach
When gentle waves carry
offshore sand back to the
beach; results in a wide
broad beach.
Rising Sea Level
Average rate is 25-30cm per century.
Global Warming
The melting of glaciers & ice sheets causes a rise
in sea level.
Longshore Current
A current that flows parallel to the coast, which
transports sand down a beach in the same direction
as the current.
Beach Erosion
Solutions
Groin or Jetty
Description
A structure protruding into the
ocean perpendicular to the coast.
Pros
Stops longshore drift from
carrying sand away from a
localized area of beach.
Cons
Causes severe depletion of sand
on the downside of the structure.
Groin or Jetty
Jetty at Rudy Inlet - Virginia Beach, VA
Seawall
Seawall
Description
An upright wall that runs parallel
along the coast.
Pros
Intended to protect uplands from
wave erosion.
Cons
Causes severe erosion of the
beach in front of it.
Breakwaters
Breakwater
Description
An offshore barrier. Japan has a
ton.
Pros
Protects the shore from the full
impact of waves.
Cons
Not very pleasant to look at.
Breakwaters at Willoughby Spit - Norfolk, VA
Underwater
Breakwater
Underwater Breakwater
Description
A breakwater that does not break
the surface & acts as a coral reef.
Pros
Protects the shore from wave
energy.
Cons
Present hidden obstacles to
surfers & boaters.
Beach Nourishment
Beach Nourishment
Description
Pumping offshore sand back to
the beach.
Pros
Presents no problems to the
beach.
Cons
Very expensive & needs to be
done about every 5 years. The
U.S. spends $1.25 billion/year.