Contents
01
Executive Summary
Overall Risk Rating
Very High
Coastal Vulnerability Index
FEMA Flood Zone
Zone VE
Special Flood Hazard Area
Local SLR Rate
3.73 mm/yr
Observed at Charleston, SC (NOAA Station 8665530)
Cat 3 Surge Depth
10 ft
NOAA SLOSH MOM estimate
This property on Sullivan's Island, South Carolina sits on a low-elevation barrier island in FEMA's highest coastal flood classification — Zone VE, with a Base Flood Elevation of 16 ft NAVD88. The site faces compounding risks: an accelerating local sea level rise rate of 3.73 mm/year at the Charleston tide gauge, a NOAA-projected intermediate rise of 1.6 ft by 2050, and Category 3 storm surge depths estimated at 10–12 ft above ground level. Sullivan's Island has a well-documented history of major hurricane strikes, and NFIP claims data for zip code 29482 reflect repeated, high-value flood losses. High tide flooding is already occurring and is projected to intensify significantly by mid-century. Any long-term investment decision for this parcel should account for substantially increasing insurance costs, potential financing constraints, and structural adaptation requirements.
02
Location & Coastal Context
Property Address
2216 Atlantic Ave, Sullivan's Island, SC 29482
Coordinates
32.7652° N, 79.8472° W
Distance to Shoreline
Approximately 0.2 miles to Atlantic Ocean shoreline
Coastal Region
South Carolina Lowcountry — Charleston Metro Coast
Geomorphic Setting
Barrier Island — Sandy Beach / Back-Barrier Marsh
Very High vulnerability
Nearest Tide Gauge
Charleston, SC (NOAA Station 8665530)
Sullivan's Island is a narrow barrier island approximately 4 miles long and 0.5 miles wide, situated at the mouth of Charleston Harbor. The island is bounded by the Atlantic Ocean to the northeast and the Intracoastal Waterway to the southwest, leaving properties exposed to surge from multiple directions during major hurricane events. Mean land elevation on the island ranges from approximately 5 to 10 feet NAVD88, with some areas well below the Base Flood Elevation. The island's barrier island geomorphology — characterized by mobile, sandy substrate and dynamic shoreline processes — makes it inherently more vulnerable than mainland or high-bluff coastal settings. The nearest NOAA tide gauge is located at Charleston, SC (Station 8665530), approximately 6 miles southwest.
03
FEMA Flood Zone Classification
VE
FEMA Zone
Special Flood Hazard Area (SFHA)
Yes — High Risk
Base Flood Elevation (BFE)
16 ft NAVD88
Mandatory Flood Insurance
Yes — required for federally-backed mortgages
NFIP Community
Town of Sullivan's Island, SC (CID: 450176)
Community Rating System (CRS)
Class 5 — 25% NFIP premium discount
Annual Flood Chance
1% annual chance (100-year flood); 26% chance over 30-year mortgage
Lowest risk
Highest risk
X
B
A
AE
V
VE
Zone VE is FEMA's highest coastal flood risk designation, indicating a 1% annual chance of flooding with associated wave action of 3 feet or more. Properties in Zone VE require federally-backed mortgage holders to maintain flood insurance, and new construction must be elevated above the Base Flood Elevation. Sullivan's Island participates in the Community Rating System (CRS) at Class 5, meaning policyholders receive a 25% discount on NFIP premiums — a meaningful offset given the high base rates in this zone. However, NFIP Risk Rating 2.0 (introduced in 2021) has moved premiums toward true actuarial risk, and future rate trajectories for VE properties are expected to increase substantially.
04
Sea Level Rise Projections
The Charleston, SC tide gauge has recorded a local relative sea level rise rate of 3.73 mm/year — one of the higher rates on the US East Coast, reflecting both global ocean warming and local land subsidence. This rate has accelerated in recent decades. NOAA's 2022 Interagency Sea Level Rise Scenarios project that under an intermediate planning scenario, the Charleston area will see approximately 1.6 feet of additional sea level by 2050 relative to 2000 baseline levels. Under a high scenario — reflecting accelerated Antarctic and Greenland ice sheet loss — that figure rises to 5.5 feet by 2100. The satellite imagery below illustrates projected inundation extent at this parcel under the intermediate scenario.
Observed Local Rate — Charleston, SC (NOAA Station 8665530)
3.73
mm/year
Based on 1921–2023 tide gauge record (NOAA CO-OPS)
NOAA Intermediate Projection — 2050
+1.6
ft above 2000 baseline
Relative to current mean higher high water
| Scenario | 2030 | 2050 | 2075 | 2100 | Description |
|---|---|---|---|---|---|
| Low | +0.2 ft | +0.4 ft | +0.7 ft | +1.0 ft | Assumes rapid emissions reduction |
| Intermediate | +0.3 ft | +1.6 ft | +2.0 ft | +3.5 ft | NOAA planning benchmark scenario |
| High | +0.4 ft | +1.1 ft | +2.6 ft | +5.5 ft | Assumes accelerated ice sheet loss |
2030 Projection
2050 Projection
2075 Projection
Partial parcel inundation
Full parcel footprint inundation
At this parcel's elevation, even the low NOAA scenario projects meaningful increases in flood frequency within the investment horizon of most coastal real estate. The intermediate scenario suggests that by 2075, areas currently flooded only during major storm events may experience regular tidal inundation. Development decisions should incorporate freeboard above current BFE to account for this trajectory.
05
Storm Surge Exposure
Sullivan's Island is directly exposed to Atlantic hurricane storm surge with no significant offshore barrier protection. Surge depths are estimated using NOAA's SLOSH Maximum of Maximums (MOM) product, which represents the upper envelope of modeled surge heights across thousands of synthetic storm tracks making landfall near this location. These figures represent worst-case estimates for each category and should be interpreted as planning-level bounds rather than precise predictions. The interactive simulation below provides a visual reference for how increasing surge depths interact with a typical coastal structure.
| Hurricane Category | Wind Speed | Estimated Surge Depth | Relative Depth |
|---|---|---|---|
| Category 1 | 74–95 mph | 2 ft | |
| Category 2 | 96–110 mph | 6 ft | |
| Category 3 | 111–129 mph | 10 ft | |
| Category 4 | 130–156 mph | 14 ft | |
| Category 5 | 157+ mph | 17 ft |
Category 1 Storm Surge — Estimated 2 ft depth at this location
Category 2 Storm Surge — Estimated 6 ft depth at this location
Category 3 Storm Surge — Estimated 10 ft depth at this location
Category 4 Storm Surge — Estimated 14 ft depth at this location
Category 5 Storm Surge — Estimated 17 ft depth at this location
Based on SLOSH MOM data, a landfalling Category 3 hurricane could produce surge of 10 to 12 feet at this location — well above the first-floor finished floor elevation of most existing structures on the island. Even a Category 1 event produces surge (2 ft) that would inundate lower-lying portions of the island. Sullivan's Island has a well-documented history of direct and near-direct hurricane strikes. Hugo (1989) produced a 20-ft surge on the northern end of the island.
06
Coastal Vulnerability Factors
The USGS Coastal Vulnerability Index (CVI) quantifies relative coastal vulnerability using six physical variables. Each factor is rated Very Low to Very High based on observed conditions along this coastal segment.
Erosion Rate
High
–0.5 m/year (shoreline retreat)
The Atlantic-facing shoreline of Sullivan's Island has experienced net erosion in recent decades, with localized hot spots retreating at rates exceeding –1.0 m/year. Beach nourishment projects have periodically offset natural losses but do not eliminate long-term vulnerability.
Sea Level Change Rate
High
+3.73 mm/year (relative)
The local relative SLR rate at Charleston is elevated by approximately 1 mm/year above the global mean due to regional land subsidence. This accelerates the effective rate of sea level encroachment compared to more stable coastal regions.
Tidal Range
Moderate
5.2 ft mean tidal range (mesotidal)
Charleston Harbor's tidal range of approximately 5 feet creates regular high-water events that amplify storm surge and contribute to increasing high tide flooding frequency as sea levels rise.
Wave Height
High
Significant wave height ~1.0–1.5 m nearshore
Atlantic-facing exposure means this stretch of coast receives persistent swell energy year-round, with significantly higher wave heights during nor'easters and tropical systems. Wave runup compounds storm surge at the shoreline.
Coastal Slope
Very High
< 0.1% coastal slope (very flat)
Extremely flat inland topography means that any water reaching the island interior — whether from overwash, surge, or rainfall — spreads widely and drains slowly. This dramatically increases flood extent and duration relative to steeper coastal settings.
Geomorphology
Very High
Barrier Island — Sandy Beach / Back-Barrier Marsh
Barrier islands are among the most dynamically unstable coastal landforms. Sandy substrates and low elevations make them highly susceptible to both storm overwash and long-term sea level encroachment.
07
Historical Flood Record
NFIP Claims — 29482
847
Claims filed since 1978
Total NFIP Payouts
$38.4M
Paid to policyholders in this zip code
High Tide Flooding Days
6 days/yr
Current observed at Charleston, SC (NOAA Station 8665530)
Projected HTF Days — 2050
35–85 days/yr
NOAA intermediate scenario
| Year | Event | Type | Estimated Damage |
|---|---|---|---|
| 1989 |
Hurricane Hugo
Category 4 at landfall near McClellanville, SC. 20-ft storm surge on northern Sullivan's Island. Catastrophic structural damage across the island.
|
Major Hurricane | $8.5B (national) |
| 1999 |
Hurricane Floyd
Category 2. Significant surge and coastal flooding along Sullivan's Island and Isle of Palms. Multiple structures damaged.
|
Hurricane | $1.2B (SC) |
| 2015 |
Historic October Rainfall
1,000-year rainfall event across coastal SC. Extensive inland and coastal flooding. Sullivan's Island roads impassable for several days.
|
Extreme Rainfall | $1.5B (SC) |
| 2019 |
Hurricane Dorian
Category 2 brush. Storm surge of 3–5 ft across the Charleston metro. Flooding of low-lying roads and properties on Sullivan's Island.
|
Hurricane | $187M (SC coastal) |
| 2022 |
Hurricane Ian (Remnants)
Tropical moisture produced sustained coastal flooding and above-normal tidal surge along the SC coast.
|
Tropical Remnants | N/A (SC impact) |
NFIP claims data for zip code 29482 reflect 847 paid claims totaling $38.4 million since the program's inception — among the highest loss concentrations in coastal South Carolina. High tide flooding at the Charleston tide gauge currently occurs approximately 6 days per year; under NOAA's intermediate sea level rise scenario, this figure is projected to rise to 35–85 days annually by 2050. This metric is a leading indicator of chronic, repetitive loss risk that insurers and lenders are increasingly pricing into coastal exposure.
08
Insurance & Regulatory Implications
Flood Insurance Requirement
Mandatory
Required for all federally-backed mortgages on properties in Zone VE. Applies at closing and must be maintained continuously.
NFIP Annual Premium (est.)
$6,000–$14,000/year
Estimated range for a residential structure in Zone VE under NFIP Risk Rating 2.0. Actual premium depends on structure type, elevation above BFE, and coverage amount. Risk Rating 2.0 moves premiums toward full actuarial cost; rates are increasing annually and are not capped for new policies.
Private Market Outlook
Limited / Withdrawing
Multiple major carriers have reduced or eliminated coastal SC exposure. Private flood markets remain available for well-elevated structures but are pricing aggressively in Zone VE. Obtain quotes from admitted and surplus lines markets.
State Disclosure Requirement
Required
South Carolina requires sellers to disclose known flood history and FEMA flood zone designation on the residential property disclosure form (SC Code § 27-50-40). Commercial transactions are subject to negotiated disclosure obligations.
Sullivan's Island enforces a local freeboard requirement of 2 feet above the BFE for all new construction and substantial improvements, which is more stringent than the FEMA minimum. All new development requires a Coastal Zone Management permit from the SC OCRM. The Beachfront Management Act (SC Code § 48-39-10 et seq.) restricts construction within the Setback Zone and may affect development potential on oceanfront parcels. Buyers and developers should obtain a detailed zoning and permitting review before committing capital.
09
Risk Mitigation Recommendations
The following recommendations are tailored to this property's specific risk profile. They are ordered by priority and estimated cost-effectiveness for long-term resilience.
1
Obtain a FEMA Elevation Certificate
An Elevation Certificate (EC) documents the structure's elevation relative to the BFE and is required for accurate NFIP rating. If the structure is elevated above BFE, the EC may significantly reduce flood insurance premiums. Engage a licensed land surveyor to prepare this document prior to purchase or construction.
2
Design to at Least 2 Feet of Freeboard Above BFE
Given the island's CRS Class 5 requirements and the projected trajectory of sea level rise, new construction or substantial improvements should target finished floor elevations of at least 2 feet above the current BFE (18 ft NAVD88 minimum). Each foot of freeboard above BFE reduces NFIP premiums and provides a buffer against future BFE revisions and sea level rise.
3
Install Flood Vents in Enclosed Foundations
FEMA-compliant flood openings (vents) in any enclosed space below BFE are required in Zone VE and help equalize hydrostatic pressure during flood events, significantly reducing structural damage. ICC-certified engineered vents may reduce the required number of openings compared to standard vents.
4
Evaluate Breakaway Wall Design for Below-BFE Enclosures
Any walls below BFE must be designed as breakaway walls per FEMA Zone VE requirements. Breakaway walls are designed to collapse under wave and flood loads, protecting the main structure from additional hydraulic forces. Ensure any existing enclosures comply.
5
Obtain a Private Flood Insurance Quote Alongside NFIP
Private flood insurance markets have expanded significantly and may offer higher coverage limits, replacement cost for contents, and coverage for additional living expenses not available through NFIP. Obtain competing quotes annually, particularly as NFIP Risk Rating 2.0 premiums continue to rise.
6
Review SC OCRM Permitting Requirements Before Any Construction
The South Carolina Office of Coastal Resource Management (OCRM) regulates development within critical areas and setback zones. Any new construction, renovation exceeding 25% of structure value, or addition requires a CAMA permit and must comply with the Beachfront Management Act setback lines. Engage a coastal permitting attorney or consultant early in the development process.