The problem for Charleston and other coastal cities, as
well as Kiawah Island, is that the number of nuisance floods
is increasing. In the 1970s there were only about two days
each year with nuisance floods in Charleston, whereas in 2015
Charleston had 38 days of tidal flooding, and in 2016 there
were 50 days of flooding. It is predicted there could be as
many as 180 days of flooding per year in the 2040s.
The source of this increasing problem is the rise in sea
level due to an increase in global temperatures, which leads
to the expansion of ocean water and melting of land-based
glaciers. (Land subsidence is also a factor in some locations.)
The increase in sea level also means that if a tropical storm or
hurricane arrives at high tide, an increase in water level that
in previous years might have caused little or no damage, is
now imposed on a higher sea level, and flooding occurs.
Sea level is rising around the globe and has risen by roughly
a foot along the southeast coast of the U.S. in the last 100 years.
The pace of increase in sea level is accelerating, and the City
of Charleston has projected that it may rise 1.5–2.5 feet by
2050 and four feet or more by the end of the century. Professor
Norm Levine, director of the Lowcountry Hazards Center at
the College of Charleston, is quoted in a recent Washington
Post article on flooding in Charleston saying that about one
percent of the buildings in the Charleston area will now see
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annual flooding. He estimates that in the next 50 years flooding
will be experienced by 15 percent of the buildings in the area.
On Kiawah, we experienced 16–20 inches of rainfall over a
four-day period in the 2015 rain event, and at least 42 percent
of the land area of the Island was flooded. During Hurricane
Matthew in 2016, the storm tide was 3.5 feet above MHHW
(mean higher high water) in Charleston, the highest since
Hurricane Hugo. (Fortunately, the storm surge did not occur
at high tide.) About 65 percent of Kiawah was covered with
some water, and considerable erosion of the beachfront dunes
occurred. More recently, in 2017 we experienced some beach
erosion because Tropical Storm Irma arrived at high tide.
Kiawah’s rainfall was approximately six inches over a two-day
event, and flooding covered at least 73 percent of the island.
These events, together with reports from organizations
such as NASA (National Aeronautics and Space
Administration), NOAA (National Oceanic and Atmospheric
Administration), the South Carolina Sea Grant Consortium,
the City of Charleston, and articles in the Post & Courier,
led in 2017 to the formation of a subcommittee of the
Environmental Committee of the Town of Kiawah Island.
Our charge was to study the effects of sea level rise on the
island and recommend possible steps to mitigate or adapt
to this slow-moving change. The committee was chaired
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