Exponential growth of private coastal infrastructure influenced by geography and race in South Carolina, USA
Data files
Apr 24, 2024 version files 3.70 MB
Abstract
Homeowners in coastal environments often augment their access to estuarine ecosystems by building private docks on their personal property. Despite the commonality of docks, particularly in the Southeastern United States, few works have investigated their historical development, their distribution across the landscape, or the environmental justice dimensions of this distribution. In this study, we used historic aerial photography to track the abundance and size of docks across six South Carolina counties from the 1950s to 2016. Across our roughly 60-year study period, dock abundance grew by two orders of magnitude, the mean length of newly constructed docks doubled, and the cumulative length of docks ballooned from 34 to 560 km. Additionally, we drew on census data interpolated into consistent 2010 tract boundaries to analyze the racial and economic distribution of docks in 1994, 1999, 2011, and 2016. Racial composition, measured as the percentage of a tract’s population that was White, positively correlated with dock abundance in each year. Median household income and dock abundance were only correlated in 2011. Taken together, these metrics indicate the growing desire for direct estuary access, however, that access does not appear to be equally spread across racial groups. Because docks enhance estuarine access and demarcate private property, our study provides longitudinal insights into environmental justice concerns related to disparate private property ownership. We found a persistent correlation between the racial characteristics of an area and dock abundance, strongly indicating that White South Carolinians have had disproportionately greater private water access for the past two decades.
README: Exponential growth of private coastal infrastructure influenced by geography and race in South Carolina, USA
This data set contains ArcGIS Pro files and a CSV of every structure identified in the study. The code used to run the models can be found on the associated Zenodo page in the "Historic_Dock_Code" folder. Additional methodological information and model diagnostics can be found in the "Historic_Dock_Supplemental" folder on the associated Zenodo page. If you have any questions or requests please email Jeffrey Beauvais (he/him) at beauvais.work@gmail.com
Description of the Data and file structure
Parent folder: Historic_Dock_ArcPro_Files
Contains a geodatabase (.gdb file) with final point layers used in the analysis for dock counts, lengths, and geographic boundaries. Intermediate files were redundant and excluded but available upon request. Some folders within are empty and automatically generated by ArcGIS Pro when loading the program. These are necessary for loading the ArcGIS Pro files. The functional files used to generate the raw data are located in the "Histortic_Dock_ArcPro_Files.gdb" (.gdb = geodatabase file), which can only be loaded within ArcGIS Pro:
- "Boundaries_OriginalNHGIS_Tracts2010_UTM": Contains 2010 tract boundaries. Only contains tracts in the 6 study counties.
- "WAI_DockCount_2011_Final_GCS": Contains only the base ("B") points of docks used in the analysis of dock counts. The attribute table contains the following columns:
- OBJECTID & OBJECTID_1: ID value automatically generated by ArcGIS Pro (unused).
- Shape: Automatically generated by ArcGIS Pro to designate the type of shape present (all values are "Point").
- Unique ID: As it sounds, a unique identifier given to each dock. Concatenation of the County, Structure_ID, and Point_Position columns.
- County: The South Carolina county the structure was located in.
- Structurte_ID: Unique number assigned to each structure.
- Structure_Type: The kind of coastal infrastructure listed.
- Point_Position: The location of the point placed on the structure. Entries are all "B" (base, where the structure connects to land).
- GISJOIN: The census tract the point is located in. Used to summarize dock information at the tract level.
- Notes: Reference notes for the structure.
- Year_Added: The year of imagery the structure was first identified in.
- Year_Defunct: The year of imagery a structure was noted to have disappeared.
- Decade_Added: As with year added, but the entry reports the corresponding census decade used the analysis.
- Decade_Defunct: As with year defunct, but the entry reports the corresponding census decade used the analysis.
- Length: The length of the structure (meters)
- X_B & X_E: The longitude of the base (X_B) and end (X_E) point (NAD 1983 geographic coordinate system). Used in tandem with Y_B & Y_E to calculate the length of the structure.
- Y_B & Y_E: The latitutde of the base (Y_B) and end (Y_E) point (NAD 1983 geographic coordinate system). Used in tandem with X_B & X_E to calculate the length of the structure.
- "WAI_DockLength_2011_Final_GCS": Contains on the base ("B") points of docks used in the analysis of dock lengths. Contains a different number of docks than those used in the count analysis because some docks underwent changes in their length during the study period (e.g., storm damage or extensions). Contains the same columns in the attribute table above.
Loose files:
- "Dock_Points_2011_8-9-2022.csv": File containing every structure identified in the study. Contains the following columns:
- UniqueID: As it sounds, a unique identifier given to each dock. Concatenation of the County, Structure_ID, and Point_Position columns.
- County: The South Carolina county the structure was located in.
- Structure_ID: Unique number assigned to each structure.
- Structure_Type: The kind of coastal infrastructure listed.
- Point_Position: The location of the point placed on the structure. Entries are either a "B" (base, where the structure connects to land) or an "E" (end).
- Notes: Reference notes for the structure.
- Year_Added: The year of imagery the structure was first identified in.
- Year_Defunct: The year of imagery a structure was noted to have disappeared.
- X: The longitude of the point (NAD 1983 geographic coordinate system).
- Y: The latitutde of the point (NAD 1983 geographic coordinate system).
- OBJECTID: ID value automatically generated by ArcGIS Pro (unused).
Sharing/access Information
All data contained therein are publishable under CC0 license. Additional pre-1990 aerial photography is owned by the University of South Carolina library. Those wishing to view these original images need to contact Bill Sudduth (sudduthw@mailbox.sc.edu) with a request.
Methods
Dock data was collected via historic aerial imagery of the South Carolina coast. Pre-1990 imagery was obtained from the University of South Carolina library, 1994 and 1999 imagery was obtained from the South Carolina Department of Natural Resources, and 2011 imagery was obtained from the US Department of Agriculture National Agriculture Imagery Program’s Geospatial Data Gateway (https://nrcs.app.box.com/v/gateway/folder/19350726983). Census data was obtained from the NHGIS and Historical Housing Unit and Urbanization Database at the tract level using their crosswalk files to interpolate 1990 and 2000 data to 2010 tract geographies.
Docks were tracked across decades in ArcGIS Pro and statistical models were run using R. Greater methodological detail is provided in the "Historic Infrastructure Methodology" file in the "Historic_Dock_Supplemental" folder on Zenodo. All pre-1990 images therein are reproduced with permission of the University of South Carolina library.
Usage notes
R, ArcGIS Pro Version 2.9 or greater.