Flooding & Hurricanes

With hurricane season ‘officially’ affecting us nearly 6 months of every year, anyone considering a move to Charleston, or as a recent arrival, has questions about hurricanes and flood zones in Charleston. Being in a flood zone is a fact of life for most of us on the Charleston Peninsula, and any of the Islands, because we live in areas completely surrounded by water. But there are nuances to it you should know about – 1. FEMA flood zones, and 2. Localized flooding (sometimes called nuisance flooding). One has to do with the cost of insurance, the other has to do with the convenience of getting around.

FEMA Flood Zones

So let’s start with the big stuff. Hurricanes! Fear of hurricanes hitting us is one of the most frequently expressed concerns of my clients moving here from other places. Understandable, yet frankly, overwrought. In 1989, Hurricane Hugo barreled ashore as a Category 4 hurricane, causing widespread destruction and devastation that took months (even years) of recovery effort.  Since then, nearly THREE DECADES passed until we had another hurricane directly hit us – Hurricane Matthew of October 2016, a Category 1-2.

Here’s an excerpt from an excellent Post and Courier article from 2012 about flood insurance and the likelihood of a BIG HIT from a hurricane in our area.


Enough Already With The Fear-Mongering

A storm is brewing in the Atlantic; forecasters are fanning out along its projected path; it has a name. Beryl. Floyd. Hugo. Time for a gut check: Does your stomach tighten? After all, isn’t South Carolina a hurricane magnet?

Maybe not.

South Carolina’s vulnerability to hurricanes is much more nuanced than the headlines on the Weather Channel might suggest. Experts say based on historical trends, minimal hurricane-force winds or higher will touch some part of South Carolina every five years.

Minimal hurricanes typically aren’t catastrophes. It’s the Category 3 and above storms that knock a city off its foundation. The 60-mile area around Charleston has seen only two of these since 1851 (Hugo and the Hurricane of 1893).

Narrow the location even more, and the situation is even less worrisome. A Post and Courier report showed that when analysts study a specific location’s vulnerability, a coastal property owner would on average see catastrophic winds every 370 years or longer.

Now that doesn’t sound so drastic does it? Frankly, if I had to pick a natural disaster, I’d pick a hurricane over a tornado, earthquake, tsunami or mudslide any day. Why? Because you have time to get the heck out of its way.

Anyway, FEMA sets its flood maps and insurance requirement based on cumulative probabilities, height of the land and proximity to water. There are lots of classifications, but the two we see most commonly on the Charleston Peninsula are AE and X, and on the Islands, AE and VE.

AE Defined – Areas subject to inundation by the 1-percent-annual-chance flood event determined by detailed methods. Base Flood Elevations (BFEs) are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply.

X Defined – Areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2-percent-annual-chance flood.

VE Defined – An area inundated by 1% annual chance flooding with velocity hazard (wave action). Most of the VE areas are along the coast, or facing the ocean on a river a bit inland. (I like to say that VE stands for VERY EXPENSIVE flood insurance)

In this graphic below of Downtown Charleston – only the white spots are in the X zone.

These few homes in the X zone do not require flood insurance, though most people elect to purchase the minimal insurance, which usually costs less than $500 per year. This rate is much less than what you would pay insurance companies when you live anywhere in the AE purple area, whether you ever see flooding in your lifetime at that particular house or not.

That is, unless the house happens to be one of the lucky ones built up, or on a hill or if it is newer construction., in which case FEMA requires that you build the house above the base elevation. For example, most of the peninsula is in AE 13 – meaning a house must be built 13 feet above sea level and the City of Charleston requires it to be at 14 feet. This is why much of Lowcountry architecture features the garage underneath the house, or very high crawl spaces. And then there’s also the conversation of flood-venting which can also affect your insurance rates. Do the cumulative square inches of the vents in your crawl space equal the square footage of the first floor of your house? And are they positioned properly – on opposing or perpendicular sides??? It’s all quite detailed – and I usually work with the insurance company and surveyor to help you figure it out.

Localized (Nuisance) Flooding

So, moving on to Point #2 – the localized flooding – or what we see when the combination of heavy rains and high tides (and watch out if the full moon is in the mix too!) is just right…er…wrong. Remember, not only are we called the Lowcountry for a very good reason, but also much of our city was built directly on top of water. For example, Market Street was once a river, which is why during particularly bad rain/high tide combinations, you’ll see people kayaking down the street.

We mostly take this localized flooding with a grain of salt and a tad of good humor around here, put on our Wellies and try NOT to drive in the areas we know to have impassable puddles unless we have a huge SUV.