www10.giscafe.com Susan Smith 11 Jul 2014
Dr. Tom Jeffrey, senior hazard scientist for CoreLogic Spatial Solutions, spoke with GISCafe Voiceabout CoreLogic’s release yesterday of its 2014 storm surge analysis that features estimates on both the number and reconstruction value of single-family homes exposed to hurricane-driven storm surge risk within the United States.
“What we’ve done we’ve tallied up all the homes that are in a high risk area along the Gulf and East Coast. We’re always trying to improve our accuracy,” said Jeffrey. “We’ve done things differently — we’ve included all designations for single family residences. In the past, we’ve used a category that has been called “single family homes” but oftentimes states have different ways of recording property information and some states use designations of mobile homes, cabins or duplexes separately. We’ve done a very comprehensive, thorough research into trying to extract all those variations of single family homes. So the total number is going to be slightly different because we believe we have a more comprehensive identification of all the homes that are potentially at risk.”
The second criteria is, how do we put a value on those homes? “In the past we used assessed value, what the tax assessment is, or what real estate identifies as what the retail value of the home is, but that was never getting to the heart of the problem,” said Dr. Jeffrey. “When a storm comes through and surge occurs, there’s going to be damage or destruction of repairing that damage or rebuilding the home. This year, for the first time, we’ve included reconstruction cost. And that’s because we purchased a company called Marshall & Swift that has that type of information. Now we extract what the reconstruction costs is going to be and we believe that’s going to be a much better indicator of what the actual dollar values are associated with the damage that would come with a storm surge activity. So it’s really a better understanding of what homes are at risk and what are the true potential costs in terms of damage.”
According to the findings, more than 6.5 million homes along the U.S. Atlantic and Gulf coasts are at risk of storm surge inundation, representing nearly $1.5 trillion in total potential reconstruction costs. More than $986 billion of that risk is concentrated within 15 major metro areas. This exposure could constitute significant risk for homeowners and financial services companies, as many at-risk homes lack protection from insurance coverage.
The analysis examined homes along the coastlines of 19 states and the District of Columbia in the Gulf and Atlantic regions, extending as far west as Texas and as far north as Maine. Florida ranks number one for the highest number of homes at risk of storm surge damage, with nearly 2.5 million homes at various risk levels and $490 billion in total potential exposure to damage. At the local level, the New York metropolitan area, which encompasses northern New Jersey and Long Island as well, contains not only the highest number of homes at risk for potential storm surge damage (687,412), but also the highest total reconstruction value of homes exposed, at more than $251 billion. Dr. Jeffrey said the Northeast has experienced more activity in the past three years than in past years.
“We evaluate the risk areas annually,” said Dr. Jeffrey. “While they don’t change dramatically, we do see some slight variations of areas. The main focus is, how does that risk relate to the properties that are currently in place?” In previous decades, anything along a coast was at risk. “Our research shows if we don’t do a broadbrush approach to this we’re going on a property-by-property basis. We can identify areas near the coastline, say in Miami, where in fact, there are properties that are not high risk.”
While scientific predictions are pointing to lower-than-normal storm activity for 2014, the risk of significant damage to homes is a constant threat. “Though the 2013 hurricane season will be remembered for the fact that no storms made landfall along the U.S. coast, this reprieve from hurricane-related damage should not lead to complacency in preparing for future storms and the potential life-threatening conditions they can bring,” said Dr. Jeffrey. “This year’s season is projected to be slightly below normal in hurricane activity, but the early arrival of Hurricane Arthur on July 3 is an important reminder that even a low-category hurricane or strong tropical storm can create powerful riptides, modest flooding and cause significant destruction of property.”
The 2014 analysis shows that total exposure varies significantly from state to state given differences in population, trends in residential development, geographic risk factors, length of coastline and other distinguishing factors. Florida and Texas, for example, are within the top five states for number of properties at risk primarily because of their extensive coastlines (Table 3). Louisiana and New Jersey, on the other hand, have a smaller coastal area overall, yet are included in the top five list as a result of relatively low elevation that allows storm surge inundation to extend farther inland and affect more homes.
The concepts in this analysis also complement Federal Emergency Management Agency (FEMA) flood zone information to provide a snapshot of potential damage exposure at the property level, as many properties located outside designated FEMA flood zones are still at risk for storm surge damage. The standard FEMA flood zones are designed to identify areas at risk for both freshwater flooding as well as storm surge based on the likelihood of either a 100-year or a 500-year flood event. They do not differentiate risk based on storm severity, and as a result, do not effectively define the total extent of the risk possible along coastal areas.
Additional findings in the CoreLogic storm surge analysis include:
- The five states with the highest total number of properties at risk include: Florida (2,488,277), Louisiana (738,165), New York (466,919), New Jersey (445,928) and Texas (434,421).
- The five states (including the District of Columbia) with the lowest total number of properties at risk include: the District of Columbia (3,895), New Hampshire (10,853), Maine (23,439), Rhode Island (26,558) and Delaware (48,534).
- The five states with the highest value of reconstruction costs for homes at risk include: Florida ($490,403,653,377), New York ($182,474,294,695), Louisiana ($161,062,467,382) New Jersey ($134,194,963,314) and Virginia ($92,001,482,217).
- The five states with the lowest value of reconstruction costs for homes at risk include: District of Columbia ($394,437,173), New Hampshire ($2,649,086,294), Maine ($6,629,856,369), Rhode Island ($7,389,384,876) and Alabama ($10,333,310,460).
The reconstruction value of the homes exposed to storm surge damage in the Gulf is much less than the reconstruction value of homes in the Atlantic region, as indicated in Table 2. The total reconstruction cost value of homes along the Atlantic coast is nearly $951 billion, which is approximately double the value of at-risk properties in the Gulf region at just over $545 billion.