Governments Plan for Development of Land Vulnerable to Rising Sea Level: Charleston County, South Carolina

Additional supplemental material

Although the cities of Charleston and North Charleston comprise one of the state's largest urban areas, Charleston County is mostly rural, and the county's comprehensive plan generally focused on priority growth areas rather than identifying the eventual land use in a final buildout. Accordingly, our maps treat undeveloped land as unlikely to be developed and protected unless specific information suggested otherwise.

Northeast of Charleston

Early drafts of this study showed Francis Marion National Forest (which comprises the eastern third of the study area) as blue rather than light green. At the time, the City of Charleston was starting to annex land in Berkeley County with plans to continue annexing east into Charleston County. The county's planners had expected USDA to oppose such annexation, but the federal government was neutral as the county designated these areas for possible growth. Timber companies in the area sold land, some of which was developed, and USDA considered land swaps. Although the majority of land was National Forest, the combination of land swaps with USDA and development of privately owned lands made it difficult to say that any particular parcel would remain undeveloped, even though the majority of land in the area clearly would remain undeveloped.

Since that time, however, the city has stopped the drive to annex lands, which leaves the area within the land use authority of the county. Therefore, the final map shows national forest lands as conservation lands and most forest company lands as unlikely to be protected.

Existing development along estuarine shores is almost certain to be protected. In the area around Awendaw, the entirety of the SC-432 loop has development and lands in that vicinity will certainly be protected, as well as the developed areas on the north wide of Awendaw Creek and developments in the Buck Hall area. The interior of the SC-432 loop, by contrast, is not yet developed though development and shore protecton area likely.

Barrier Islands

Dewees Island has no bridge connection to the mainland. Nevertheless, the county still believes that it is likely to be protected, given the moderate development that is expected to continue; protection applies primarily to the portion of the island with roads. The more densely developed Isle of Palms and Sullivans Island are almost certain to be protected. The only exception is the private golf course at the eastern end of Isle of Palms. This development appears to be worth protecting, but it would not be eligible for federal funding. Hence, if erosion were to accelerate substantially and/or available sand for nourishment was limited, it would have a lower priority for limited sand supplies than more densely developed communities that are open to the public.

South of the entrance to Charleston Harbor, Morris Island is still undeveloped and lacks road access. Thus, the planners do not believe that one should assume that this island is certain to be protected. Nevertheless, development is sufficiently likely to assume that this island will probably be protected. Folly Beach has received beach nourishment as compensation for erosion caused by navigation projects, but the county's understanding is that no additional funds will be forthcoming on that basis. Nevertheless, parts of this barrier island suburb of Charleston are densely developed and almost certain to be protected. Prospects for shore protection are somewhat less, however, for the part of the island northeast of the washover (i.e., the narrow part of the island where storms occasionally wash over the road).

Seabrook and Kiahwah are gated barrier islands closed to the public and hence ineligible for beach nourishment funding (although Kiahwah also has a park that is sometimes open to the public).. The investment on these islands is greater than the cost of shore protection, hence these shores are likely to be protected. In the unlikely event that sand supplies or environmental considerations limited the portion of the county that could be nourished, however, these islands would have a lower priority than Folly Beach, Sullivans Island, and Isle of Palms. Therefore the maps show Seabrook and Kiahwah islands as likely, but not certain, to be protected.

Other Islands

James and John's Islands are both either developed or likely to become developed, and hence both are shown as a combination of likely and almost certain to be protected.

Most of Wadmalaw and Edisto islands are agricultural, except for small areas just across the bridges from Seabrook Island and Edisto Beach, respectively. Much of Edisto Island is owned by the descendants of freed slaves, with large parcels often being jointly owned by several dozen people. To help clear title without divesting people of minor fractional ownership, the County allows land to be subdivided into parcels as small as one acre in many areas. These areas are known as "agricultural-residential" (AGR). The County recently conducted a settlement area study, which mapped areas with existing and proposed AGR zoning. County planners suggested that we use the maps from that study to identify areas that will probably be developed for these two islands, which are shown as shore protection likely. The rest of those islands are unlikely to be protected.

Mainland West of Charleston

The areas immediately to the west of Charleston are developing. Farther to the west, Parker's Ferry is the only area of significant development where shore protection is certain. As with Edisto and Wadmalaw islands, the County suggested that we use the Settlement Area Study to identify other areas where future development and shore protection are likely.

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Governments Plan for Development of Most Land Vulnerable to Rising Sea (PDF, 7 pp., 1.3 MB, was originally published in Environmental Research Letters , Issue 3, Volume 4 (2009).