Transcript Louisiana Coastal Erosion - Nicholls State University

Louisiana
Coastal Erosion
The problem
• LA contains approximately 40% of the nation's
wetlands and experiences 80% of the nation's
coastal wetland loss.
• LA is losing 25 to 35 square miles of wetland per
year and the highest rates are occurring in the
Barataria and Terrebonne basins at 10 and 11
square miles per year.
• At current land loss rates, an area the size of
Rhode Island will be gone by 2050.
• With 500 million tons of waterborne cargo passing
through Louisiana's system of deep-draft ports and
navigational channels, Louisiana ranks first in the
nation in total shipping tonnage.
- If present land loss rates continue, more than 155
miles of waterways and several of the ports will be
exposed to open water within 50 years.
• LA's commercial fisheries are the most bountiful of the
lower 48 states, providing 25% - 35% of the nation's
total catch. LA is first in the annual harvest of oysters,
shrimp, crabs crawfish, red snapper, wild catfish, sea
trout and mullet.
- By 2050, the annual loss of commercial fisheries will
be nearly $550 million. For recreational fisheries, the
total loss will be close to $200 million a year.
Problem (continued)
• Wetlands and barrier islands provide a
protection barrier from strong winds and
hurricanes: every 2.7 miles of wetlands absorbs
one foot of storm surge.
• Data from past hurricanes indicates that the loss
of every one-mile strip of wetlands along the
coast, results in an estimated $5,752,816
average annual increase in property damage.
• Between 60 and 70% of LA's population lives
within 50 miles of the coast.
Economic Impacts to LA and the
Nation
• LA's wetland loss could cost the nation $36.6
billion from lost public use value over the next 50
years.
• 18% of U.S. Oil Production; 24% of US natural
gas production originates, is transported
through, or is processed in LA coastal wetlands.
- One fourth of our nation's energy supply
depends on the support facilities in South
Louisiana.
- LA's oil and natural gas industries have a value
exceeding $16 billion a year.
Annual precipitation and runoff for continuous corn watersheds,
no-till and conventional tillage, 1979-1988
year
Precipitation
mm
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1124
1175
1057
889
1027
909
929
966
841
854
runoff
no-till
mm
runoff
conventional
mm
3.81
4.90
0.14
0.00
0.00
2.31
0.01
9.23
0.15
0.03
140.2
312.8
142.2
-
Source: W M Edwards: Soil structure: process and management in Lal
& Pierce: Soil management for sustainability, 1991.
How erosion occurs
• Storms often cause coastal erosion, in
particular those storms that have high
winds and big waves. These waves
eventually wash away the soil and rocks
that are built up in the land. What is now
the coast in many areas, used to be miles
away from the coast.
• In Louisiana hurricanes are a big contributor to
the erosion of our coast.
• When these storms come, their high winds and
wave take out the barrier islands that protect the
coast. After years of hurricanes all of the old
barrier islands have disappeared and one of the
new islands protecting our state is Grand Isle.
Unfortunately this island may not have much
time left.
A COMMON KNOW FACT
• No matter what,beaches suffer from a
natural retreat in its shoreline. This is not
what makes erosion a problem is human
made stuctures. When a person builds a
structure on the shoreline it interrupts the
natural process that a beach goes
through.
A Kick In The Groin
• Property owners put up rock walls along
the shore called a groin. This at the time
was a simple solution to progressing
erosion . It worked by slowing the currents
down and gathering sand on the up drift
side of the wall. But it was soon
discovered that these structures helped
the property owners and took away from
the beaches.
Solution
• Already in effect are the piles of rock often
called jetties that reduce that break down
the waves before they reach the beach,
this had saved a lot of the beach and
Grand Isle and it is possible that itwould
do the same in other areas.
Solution (continued)
• A possible solution is that all areas with
beaches make a setback point. This is the
point where the shoreline is estimated to
be in 100 years. This would prevent
building structures too close to the beach.
Breakwaters
• Another simple and affective solution is
building offshore breakwater structures
that will reduce the wave energy before it
reaches inland, therefore reducing the
amount of impact that a wave has on the
inland. This will decrease the amount of
land lost.
Our Solution
• Louisiana’s coastal erosion is caused by
the diversion of the Mississippi river. It is a
known fact that all of our land was built up
by sediment that flowed down the
Mississippi. If we were to diverge the
Mississippi back to its normal route it is
possible that it would build our lands back
up.
• http://www.restoreorretreat.org/coastal_erosion.
html
• http://www.cclockwood.com/stockimages/coastal
erosion.htm
• http://marine.usgs.gov/factsheets/LAwetlands/lawetlands.html
• http://www.seafriends.org.nz/enviro/soil/erosion.
htm
• http://thejump.net/erosion/LaErosion.htm#jump2