Seawalls oftentimes fail due to the following reasons:
-Material erosion
-Poor design
-Structure aging
-Toe erosion

Since this program can apply to any kind of vertical wall for the purpose of shoreline protection, we thought one good example of seawall failure was the levees in New Orleans.

When Hurricane Katrina hit the Southern coast of the U.S., the levees surrounding that area failed.  This happened because the average water level usually never even touched the levee walls.  The extra water from the hurricane put extra pressure on the levee wall and on the ground.  The extra pressure weakened the soil which then allowed the high pressure to eventually push the entire wall backwards thus causing it to fail.  This happened because the levees were not properly designed.  Had they been initially constructed to handle higher water levels, the extensive flooding that occurred in New Orleans could have possibly been reduced or even avoided.

Seawall failure is a major cause for concern because they can quite expensive to repair or replace if the damage is extensive enough.  Also, since seawalls are being used for shoreline protection, that shoreline is longer being properly protected.  This is why it is important to ensure that seawalls are properly designed and repaired if need be.