data layers used in this process included orthorectified imagery gathered by USDA during the agricultural growing season through the National Agriculture Imagery Program [ NAIP ] captured annually .
The resulting digitized shorelines were then combined and analyzed for temporal-spatial changes to the marsh shorelines over time . Altogether , eight ( 8 ) individual years of shoreline data from 1994 to 2019 were digitized and analyzed to understand changes in vegetated marsh shorelines . Additional data layers for 1854 , 1934 , and 1977 were created for reference using historical maps and aerial imagery . Symbology was developed to better illustrate shoreline changes by highlighting areas of erosion with red-colored gradients and areas of accretion with green-colored gradients . Subsequent analysis was performed by graduate student Kaylee Smith using the Digital Shoreline Analysis System ( DSAS ), an alternative to AMBUR , to quantify the changes in marsh shoreline position .
The Digital Elevation Model ( DEM ) provided by S . C . Department of Natural Resources ( 2017 ) for Charleston County was used for improving understanding of shorelines and relative elevation . The DEM serves to provide quality assurance and quality control for the project by cross-referencing relative elevation with the digitized shorelines . The resulting products from the marsh vulnerability project can be used to better understand the impacts to the marsh over time and identify vulnerable areas to prioritize habitat restoration projects .
Figure 6 . Erosion and accretion rates within the region of Bass Creek and Cinder Creek on Kiawah Island . Map produced by Alex Braud for the Santee Cooper GIS Laboratory and Lowcountry Hazards Center ( 2021 ).
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