A team of UK-US engineers and scientists have presented their findings, after using cutting-edge technology to study flood patterns in the US. The results of the study, which were detailed at the 2017 American Geophysical Union meeting, appear to show that the current flood hazard maps used by the Federal Emergency Management Agency (FEMA) are woefully out of date and incorrect. The official FEMA flood hazard map is used to determine which properties must carry mandatory flood insurance, based on the officially-assessed risk. If the flood hazard zones are incorrectly identified, many properties may be left at risk of uninsured damage or destruction.
According to the team of researchers, there are approximately 40 million people now living within areas that have a 1% chance of flooding each year. This sounds inconsequential at first perusal, but this level of flood risk is also known as the ‘100-year floodplain’. As we know from recent disasters, the 100-year floods are happening with dreadful regularity in many parts of the US, often in locations that have never flooded before! If a property experiences flooding that was considered by FEMA to be improbable, it is likely that the property was not insured- in which case the owners stand to lose everything without compensation- the funds needed to rebuild. This scenario can destroy lives as well as houses.
As the map above shows, as of April 2017, much of the country has already received updated flood maps in the form of preliminary or effective Flood Insurance Rate Maps (FIRMs). Source: FEMA.gov
Although the new study estimates 40 million people living inside the risk zone, FEMA estimates only 13 million people are living within the 100-year floodplain … a substantially smaller risk pool. This means that as many as 27 million people may be at risk of being underinsured or completely uninsured for flood damage because their property has not been determined by FEMA to be at risk. It may be that many of these people are living with a very false sense of security!
Why do the FEMA numbers differ so drastically from the results presented by the UK-US scientists? This is a question of profound importance to the many millions of people who may be risking disaster, as well as to the engineers and scientists at FEMA who compile the statistics to produce the official flood hazard maps. According to the scientists who were involved with the study, FEMA concentrates too heavily on coastal flooding, and not enough attention is given to floodplains close to rivers, which can be subject to flash flooding during heavy rainfall. The new study was conducted with improved scientific techniques that identified every possible flood zone along US rivers, and here they simulated heavy precipitation events. The results of these simulations are a wake-up call to those who own property in these areas.
So far, the results of this alarming new study have not been utilized by FEMA officials, but the agency is aware of the study and is taking a look at the newly-released data. If the results are embraced and translated into action, many millions of people in the US will find themselves suddenly in need of expensive flood insurance. That would be a hardship, to be sure. But with trillions of dollars worth of assets currently unprotected, an even greater hardship looms as a very real possibility.