At long last, and with much anticipation, the Lowcountry has its updated flood zone maps.
During nearly five years of review, the process understandably became a bit complicated as a number of agencies – FEMA, Charleston County, and the state’s SC Department of Natural Resources – analyzed mountains of data from flood-prone areas to assess actual risks, sometimes parcel by parcel.
The purpose of these maps is to provide accurate guidance to insurance providers and building permit offices, and whose ultimate effect on homeowners is a potential impact on their flood insurance requirements and rates.
A Better Model for Flood Zones
Charleston County has been operating with flood zone maps that were last updated in 2004, and while these maps needed an update to reflect new data and sea level rise, they were also based on a flawed model of determining flood risk. The primary determinations of flood zones in the current maps are based on storm surge predictions during a Category 3 hurricane, however we all know that flooding can occur during significant non-tropical rainfall events.
We have witnessed incidences of homes that were deemed lower risk in the storm surge models, but tragically suffered substantial water damage from non-tropical factors – typically a heavy summer storm combined with a high tide.
Updated flood zone maps will be based not only on storm surge data but also on flooding that results from rainfall accumulation and tidal forces.
Also, inaccuracies in the storm surge estimates have been improved with data from recent tropical storms, and that data has been incorporated into the maps to adjust the flood zone elevations.
Assessing the Risk
The new flood zone maps that take effect in January 2021 will impact tens of thousands of properties in Charleston County. Most assuredly, there are some homes previously listed as low risk that will now be escalated. However most of the properties in Charleston County with adjusted flood zone designations will be deemed lower risk than on current maps – many of which have been required to carry flood insurance despite having never experienced flooding, even during major weather events.
Cumulatively, this means that not only will flood insurance rates be more reflective of actual risk, but also home buyers will be able to assess the potential flooding threats to their home with greater confidence. Some homes will be subject to higher flood insurance rates while many, many others will see relief from them.