effective means to substantially reduce loss of life for large hurricane events” (p. I-4), and, “The emergency response preparedness and efficiency of evacuation prior to a storm is a key component to reducing risk to life and human safety” (p. I-5). It also explains clearly that much of the region remains subject to hurricanes and it does a good job at explaining the concept of residual risk—“No matter how well designed an HPS may be, some level of residual risk always remains: risk is never reduced to zero” (IPET, 2008, VIII-12).
The potential virtue of marshes, wetlands and other vegetation in protecting inshore areas from storm surge has been a topic of considerable speculation following hurricane Katrina, particularly given the documented loss of significant areas of marshes in southern Louisiana during the past 50 years. The IPET made a reasonable effort to include the effects of these landscape features in their storm surge and wave modeling with equivocal results. Considerable uncertainty remains about how to properly represent these effects in surge and wave models and in the resulting model sensitivities. Given the major investments that are being discussed for marsh restoration projects in southern Louisiana (see USACE, 2007; State of Louisiana, 2007), and the partial justification for these projects based on their value for increased hurricane protection, it is important that additional efforts be taken to improve understanding of the effects these features have on hurricane wave and storm surge across this region.
In addition to the inundation maps generated in the IPET studies, the Federal Emergency Management Agency (FEMA) is in the process of updating its Flood Insurance Rate Maps (FIRMs) to provide delineation of the 100-year flood elevation for southern Louisiana. Also, the National Hurricane Center (part of the National Oceanic and Atmospheric Administration, or NOAA) has produced a set of maximum flood elevation maps for hurricanes of various categories, tracks, forward speeds, and other variables that are used primarily for evacuation planning.
Although IPET, FEMA, and NOAA have different objectives and product needs, these agencies should engage in ongoing communication and coordinate to ensure consistency among their methods and the resulting products.