Levees are made from compacted soil, whereas floodwalls are erected from man-made materials, usually metal and cement. If forecasted flood levels prove true, floodwaters will rise over levees for the first time since the system was upgraded post-Hurricane Katrina. In 2005, over 50 levees failed throughout New Orleans, leaving 80 percent of the city underwater. However, because water has never made it over the retaining walls before, this erosion-prevention system has never been tested in practice. Water that overtakes the levees would be pumped out by the same water pumps used to divert rainwater that falls within the levee's walls outside of its perimeter.

Source: The Nation August 29, 2021 14:48 UTC