Human Impact on Beaches
Erosion and the Outer Banks
• Read the article on Outer Banks beach erosion
• As you read, highlight words or things that you
do not know.
• Once you finish reading, write a summary of
the article.
Longshore Drift
• When swimming in
the ocean, have
you ever wondered
why you tend to be
carried down the
beach, away from
your towel in an
undertow?
• The transportation
of sediments along
a coast at an angle
to the shoreline
Preventing Beach Erosion
• Sea Wall – a structure
to protect a coast
from erosion
– Built parallel to the
shore
– Designed to shield the
coast and defend
property from the
force of breaking
waves
•Causes the sediments in
front of the wall to be
swept in the ocean.
•Further loss of beach
prompts people to build a
bigger, “better” wall to stop
the erosion caused by the
original seawall.
Preventing Beach Erosion
• Breakwater - sediment
movement is blocked
from continuing along
the coastline, disrupting
the longshore transport.
– Built parallel to the shore
line
– Protects boats from the
force of large breaking
waves by creating a quiet
water zone near the
shore
Preventing Beach Erosion
Groin - designed to trap
sediments in an area of
the beach.
–disrupt the longshore
transport
–Perpendicular to the
shore
–the beach on the other
side of the groin will
continue to loose
sediments
Preventing Beach Erosion
Preventing Beach Erosion
• Beach Nourishment – sediment lost through
long shore drift or erosion is replaced
• Beach nourishment video
– http://outerbanksvoice.com/2011/07/14/see-24hours-of-beach-nourishment-in-2-minutes/
Preventing Beach Erosion
• Vegetation –
helps hold
sand in place