Predicted Sea Level Rise and Seabrook Island

by Lucy Hoover

In February, the National Oceanic and Atmospheric Administration (NOAA) issued a report that stated the pace of ocean rise is accelerating. The most vulnerable areas in the United States are surrounding the Gulf of Mexico and the Atlantic Coast. Seabrook Island is within this zone. Anyone familiar with the Island, especially in the last few years, does not need a scientific report to verify this. We have noticed “sunny day” nuisance flooding during King Tide events, increased flooding during heavy rains, marshy areas moving into what was once dry land, and the dynamic changes to our beach areas. All of these are indicators of a rising sea level.

 Oh my! Do we all pack up and head for high ground? No, we believe that is an unnecessary overreaction. Instead, there are methods to mitigate the flooding and encroachment caused by the rising ocean waters. For example, SIPOA is relining older drainage pipes, installing check valves at outfalls, and improving Seabrook Island’s stormwater drainage system as an outgrowth of a 2018 agreement between SIPOA and the Club. These projects will help mitigate the impacts of tidal flooding during King Tide events and provide more effective drainage of the roadways during and after rain events. For more detailed information about flooding, go to sipoa.org on the home page click on “Flood Education Program.”

 Property Owners can also mitigate stormwater runoff or occasional flooding by working closely with SIPOA ARC or other staff to review the many non-invasive and effective options available to direct runoff and drainage away from homes and into the existing stormwater systems. For example, one clever and environmentally friendly method to help manage water is to plant rain gardens. After heavy rainfall, rain gardens collect runoff from the surrounding hardscapes and allow the water to seep into the ground slowly, naturally filtering runoff before entering the water table and surrounding marshes. If a rain garden is an appropriate solution, the ARC staff can help locate the garden and suggest suitable plants tolerant of wet and dry conditions.

 Seabrook Island is also protected from sea level rise by our conserved green spaces. Each undeveloped area functions as a sustainable stormwater management system filtering rain and runoff. Scientists estimate that a live oak situated in undeveloped green space in our environment will absorb 30% of the rainfall that passes through its canopy before hitting the ground. Sandy soil absorbs water quickly, but the more nutrient-rich soils in an undeveloped area act as a filter for the water that enters the underlying aquifer slowly. Then, the plant’s roots absorb much of the water for nourishment. 

 As we all learned in elementary school, plants absorb carbon dioxide, which breaks down into organic compounds used to promote the plant’s growth, and then plants release oxygen into the atmosphere. Scientists believe carbon dioxide adds to global warming and rising sea levels. Green spaces help mitigate the amount of carbon dioxide in the atmosphere. When there’s new construction on the Island, Seabrook Island tries to offset the removal of plant life by limiting the allowable percentage of impervious surfaces such as roofs and driveways on each lot. And trees removed during construction may need to be mitigated through thoughtful landscaping. 

 As the ocean rises, it naturally occurs through the marshes. Marsh grasses tolerate the salinity of the water and help filter and clean this ecosystem. As a marsh grows or expands onto previously dry land, marsh plants replace the existing flora. Any conserved marsh-front property slows encroachment into developed areas.

 On Kiawah Island, the Kiawah Island Conservancy’s Lee Bundrick and students from the College of Charleston are conducting a long-range study to measure the depth and salinity of the groundwater in several areas on the Island. A decrease in depth before hitting the aquafer and an increase in salinity would indicate a rise in sea level. The study will provide a baseline to show which specific areas of Kiawah would be most vulnerable to an increase in saltwater. Their findings will be helpful as we plan to conserve properties or mitigate water on developed properties.

 Yes, sea level rise is occurring more quickly than previously thought. But we can achieve better resilience and plan for the coming changes through careful planning and planting by homeowners and the conservation of additional undeveloped areas on and around Seabrook Island.

 The Seabrook Island Green Space Conservancy is a 501(c)(3) organization formed to preserve and enhance the natural environment on Seabrook Island through the acquisition of land and land easements, through education on environmental topics, and through advocacy of conservation issues. Please visit our webpage www.sigsc.net and consider donating to help preserve the Island we all cherish.