Geology Reference
In-Depth Information
Figure 16.19 Hurricane Katrina, 2005
c Destruction caused by the storm surge from Hurricane Katrina.
This image shows a man in Biloxi, Mississippi, trying to fi nd his
house.
a On August 29, 2005, the Hurricane Katrina made landfall along
the Gulf Coast. In this image, the eye of the storm is passing just to
the east of New Orleans, Louisiana.
d This is a repaired section of fl oodwall in New Orleans. This
barrier is along one of the canals leading into the city from Lake
Pontchartrain. Failure of the fl oodwalls during and following Hurricane
Katrina caused fl ooding of about 80% of New Orleans.
b Although many areas were hit hard by Katrina, New Orleans was
extensively fl ooded when the fl oodwalls failed that were built to
protect the city from Lake Pontchartrain and the Mississippi River.
thermal expansion of near-surface seawater. Many scientists
think that sea level will continue to rise because of global
warming caused by increasing concentrations of greenhouse
gases in the atmosphere.
The second factor that controls sea level is the rate of
uplift or subsidence of a coastal area. In some areas, up-
lift is occurring fast enough that sea level is actually fall-
ing with respect to the land. In other areas, sea level is
rising while the coastal region is simultaneously subsiding,
resulting in a net change in sea level of as much as 30 cm
per century. Perhaps such a “slow” rate of sea level change
seems insignificant; after all, it amounts to only a few
millimeters per year. But in gently sloping coastal areas, as
in the eastern United States from New Jersey southward,
even a slight rise in sea level will eventually have wide-
spread effects.
Many of the nearly 300 barrier islands along the East and
Gulf Coasts of the United States are migrating landward as
sea level rises (
Figure 16.20). Landward migration of bar-
rier islands would pose few problems if it were not for the nu-
merous communities, resorts, and vacation homes located on
them. Moreover, barrier islands are not the only threatened
areas. For example, Louisiana's coastal wetlands, an important
wildlife habitat and seafood-producing area, are currently
 
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