Coastal Construction Manual - National Ready Mixed Concrete ...

2 HISTORICAL PERSPECTIVE
Figure 2-12.
Structures built close
to the downdrift side of
groins and jetties can
experience increased
erosion rates
SOURCE: ADAPTED FROM
MAINE GEOLOGICAL SURVEY
2005
When levees fail, it is often catastrophic. In 2005, Hurricane Katrina’s storm surge caused failure of the
certified levee system protecting New Orleans, LA, and flooded almost 80 percent of the city, making
Hurricane Katrina the most destructive natural disaster in the history of the United States. The flooding was
caused by a combination of breaching and overtopping. Flood levels were higher than the BFE for most of
the affected area, rising well above the first floor, even for buildings elevated above the BFE.
An additional hazard related to levee overtopping or breaching is
that resultant flooding may have a much longer duration, perhaps
as long as a few weeks, compared to that of coastal floods, which
typically last a day or less. Long-duration floods can increase
damage to buildings through mold growth, corrosion, and other
deterioration of building materials.
CROSS REFERENCE
Section 3.6.9 discusses NFIP
treatment of levees.
No levee is flood-proof, and regular inspection, maintenance, and periodic upgrades of levees are necessary
to maintain the desired level of protection. Homeowners sited behind levees should take precautions, such as
elevating and floodproofing their homes, and be prepared to evacuate in an emergency. For more information,
refer to So, You Live Behind a Levee! (ASCE 2010b).
2.3.3 Design
Building design is one of the most important factors of a successful coastal building. Observations of building
damage resulting from past storm events have not only provided insight into the design of coastal buildings,
but have led to positive changes in building design codes and standards. Newer buildings built to these codes
tend to perform better. However, certain design flaws still exist and are observed year after year.
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