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The
Simpson Creek Watershed Study
The
EARTHWORKS Group conducted a watershed study of the Simpson Creek drainage
basin located in Horry County, South Carolina to determine the 100 year
flood elevations upstream of the S.C. Highway 905 Bridge. The watershed
upstream of the S.C. Highway 905 Bridge was an unnumbered “A” flood
zone, with the base flood elevation undetermined. Downstream of the S.C.
Highway 905 bridge, the Waccamaw River basin has flood elevations
established up to Star Bluff Road. The FIRM panels show the published
flood zone is an AE18 in this section of the Waccamaw River. The purpose
of this study was to establish an elevation for the development of the
Polo Farms Phase 2 residential subdivision.
ICPR
was used for both hydrologic and hydraulic modeling of this 41-square mile
watershed in an effort to establish Base Flood Elevations in the
unnumbered "A" zone of the study area. Baseline information was
collected during 2005 and assembled using a Geographic Information System
(GIS) to include aerial photography, USGS quadrangle maps, National
Wetland Inventory maps, SCS soils maps, Horry County digital terrain model
(DTM) data, and discrete survey information collected from the major nodes
and cross sections within the watershed. The watershed was divided into 20
sub-basins using the DTM data, and curve numbers were assigned based on
the existing soils and land use shown on the 2004 aerial
photography.
The
study was submitted to and approved by FEMA as a map modification to the
existing Flood Insurance Rate Maps (FIRM) data and allowed a national
housing developer to continue the second phase of a residential project.
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Project
Location
The
study area is located in Horry County, South Carolina approximately 15
miles northeast of Conway.
Location
Map
Contact
Information
For
more information on this project, please contact Mark
Donevant with Earthworks.
Report
Information
For
more information on this project, you can download
the final report
from Earthworks' website.
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