Let’s Talk about Flooding on Seabrook Island
This is the first of a three-part series on flooding and storm tides.
First, a little background….
Surface water drains by gravity and on a small island, such as Seabrook, water seeks sea level. Of course, the higher the level that surface water can drain from and the greater the slope, the faster it drains. If there is no lower level for the surface water to drain to due to ground saturation or high tide, the water will pool causing flooding. On our island, the soil is sandy and drains well, but the water table and the sea level are close to the land surface, limiting drainage.
Seabrook Island’s drainage infrastructure, which is a system of lagoons, ponds, weirs, swales, pipes, valves and pumps, has done a reasonable job of draining the surface water in normal events over the past 45 years. There are approximately 130,000 linear feet of stormwater pipe, 48 stormwater ponds, and 3 stormwater pump stations on the island. The continued build-out of Seabrook Island results in less land for stormwater infiltration into the soil. More recently SIPOA has been working to improve the drainage system and has installed additional measures such as check valves on drainage pipes to reduce tidal flooding. However, given the flat, low-lying nature of our island, there are always limits as to how much rain precipitation, high tide, or storm tide the system can handle without flooding parts of the island. Therefore, we must accept that extreme rain events, high tide events, and storm tide events have always been a fact of life on Seabrook Island and will, in spite of our best efforts, bring flooding when they occur.
-Submitted by the SIPOA General Operating and Maintenance Committee