First Infrastructure Line Vector, North Carolina (2018-2021)

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Metadata:

Identification_Information
Data_Quality_Information
Spatial_Data_Organization_Information
Spatial_Reference_Information
Entity_and_Attribute_Information
Distribution_Information
Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: Alexander C. Seymour
Originator: Kara S. Doran
Originator: Margaret L. Palmsten
Publication_Date: 20260310
Title: First Infrastructure Line Vector, North Carolina (2018-2021)
Edition: 1.0
Geospatial_Data_Presentation_Form: vector digital data
Larger_Work_Citation:

Citation_Information:

Originator: Alexander C. Seymour
Originator: Kara S. Doran
Originator: Margaret L. Palmsten
Publication_Date: 20260310
Title: First Infrastructure Line Vector, North Carolina
Series_Information:

Series_Name: U.S. Geological Survey data release
Issue_Identification: doi:10.5066/P9GL68X8

Publication_Information:

Publication_Place: St. Petersburg, FL
Publisher:

U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

Other_Citation_Details: 2026a
Online_Linkage: https://doi.org/10.5066/P9GL68X8

Description:

Abstract:

The U.S. Geological Survey (USGS) supports multiple efforts to understand and predict storm impacts to our nation's coastlines. The first infrastructure line is defined as the seaward boundary of the first row of structures or roads in a coastal area and can be used to assess coastal vulnerability. The first infrastructure line as defined in this dataset represents a cross shore boundary where the most intense hold-the-line management actions are likely to be taken to prevent further landward transgression of the foredune. Certain built features, which often extend far seaward from primary residences and commercial buildings, including boardwalks, swimming pools, gazebos, and sheds, are not included in this first infrastructure line. This dataset is optimized for use in measuring the distance between the first infrastructure line and seaward protective features, particularly coastal dunes. The first infrastructure line in North Carolina (NC) was digitized along the developed ocean-fronting portion of the coastline using imagery/orthomosaics collected by the National Agriculture Imagery Program (NAIP), National Geodetic Survey (NGS), and the Environmental Systems Research Institute (Esri)between 8/26/2018 and 7/16/2021.

Purpose:

To provide the seaward boundary of the first infrastructure line as a vector shapefile (.shp). The methods used to digitize these data are described in "Decadal-scale characteristics of natural and anthropogenic dune morphology along North Carolina barrier islands (SE Atlantic coast)" by Seymour and others (2026b) and are also described in the process steps of this metadata record.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20180826
Ending_Date: 20210913

Currentness_Reference: ground condition

Status:

Progress: Complete
Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -78.516845
East_Bounding_Coordinate: -75.461508
North_Bounding_Coordinate: 36.5496588
South_Bounding_Coordinate: 33.843362

Keywords:

Theme:

Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:daf5f6fc-198c-4bab-b400-3d868789b833

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificInformation
Theme_Keyword: oceans
Theme_Keyword: environment
Theme_Keyword: structure

Theme:

Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: hazards
Theme_Keyword: marine geology
Theme_Keyword: ocean sciences
Theme_Keyword: coastal processes
Theme_Keyword: erosion
Theme_Keyword: floods
Theme_Keyword: geospatial datasets

Theme:

Theme_Keyword_Thesaurus: None
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: St. Petersburg Coastal and Marine Science Center
Theme_Keyword: SPCMSC
Theme_Keyword: Coastal and Marine Hazards and Resources Program
Theme_Keyword: CMHRP
Theme_Keyword: Coastal Change Hazards
Theme_Keyword: CCH

Place:

Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: North Carolina
Place_Keyword: Atlantic Ocean

Access_Constraints: None
Use_Constraints:

Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originators of the data in future products or derivative research.

Point_of_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

Contact_Person: Kara S. Doran

Contact_Address:

Address_Type: mailing and physical
Address: 600 4th Street South
City: Saint Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: United States

Contact_Voice_Telephone: 727-502-8117
Contact_Facsimile_Telephone: 727-502-8001
Contact_Electronic_Mail_Address: kdoran@usgs.gov

Native_Data_Set_Environment:

Windows 10 Enterprise 21H2 (Build 19044.1826); Esri ArcGIS Pro 2.7.1

Cross_Reference:

Citation_Information:

Originator: Alexander C. Seymour
Originator: Daniel J. Ciarletta
Originator: Kara S. Doran
Originator: Margaret L. Palmsten
Publication_Date: 20260305
Title:

Decadal-scale characteristics of natural and anthropogenic dune morphology along North Carolina barrier islands (SE Atlantic coast)

Series_Information:

Series_Name: Journal of Coastal Research
Issue_Identification: Unknown

Other_Citation_Details: 2026b
Online_Linkage: https://doi.org/10.2112/JCOASTRES-D-25-00053.1

Cross_Reference:

Citation_Information:

Originator: Chelsea A. Stalk
Originator: Karen L.M. Morgan
Originator: Jenna A. Brown
Originator: Christopher R. Sherwood
Publication_Date: 20200408
Title:

Ground Control Point Locations, Elevations and Photographs From North Topsail Beach and Camp Lejeune, North Carolina, June 2019

Series_Information:

Series_Name: U.S. Geological Survey data release
Issue_Identification: doi:10.5066/P9R9DPFS

Publication_Information:

Publication_Place: St. Petersburg, Florida
Publisher:

U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

Online_Linkage: https://doi.org/10.5066/P9R9DPFS

Cross_Reference:

Citation_Information:

Originator: Jenna A. Brown
Originator: Christopher R. Sherwood
Originator: Marinna Martini
Originator: Christine J. Kranenburg
Originator: Jin-Si R. Over
Publication_Date: 20210408
Title:

Ground Control Point Data from the Outer Banks, North Carolina, post-Hurricane Dorian, September 2019

Series_Information:

Series_Name: U.S. Geological Survey data release
Issue_Identification: doi:10.5066/P9DVZC23

Publication_Information:

Publication_Place: St. Petersburg, Florida
Publisher:

U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

Online_Linkage: https://doi.org/10.5066/P9DVZC23

Cross_Reference:

Citation_Information:

Originator: North Carolina Department of Environmental Quality
Publication_Date: 1974
Title: North Carolina Coastal Area Management Act of 1974
Publication_Information:

Publication_Place: Raleigh, NC
Publisher: North Carolina Department of Environmental Quality

Online_Linkage:

https://deq.nc.gov/about/divisions/coastal-management/coastal-management-rules-regulations/coastal-area-management-act

Data_Quality_Information:

Logical_Consistency_Report: No formal logical accuracy tests were conducted.
Completeness_Report:

This dataset is considered complete for the information presented, as described in the abstract section. Alongshore gaps are present in the first infrastructure line vector where no infrastructure exits within 500 m of the shoreline. Users are advised to read the rest of the metadata record carefully for additional details.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Cumulative cross shore positional uncertainties of the first infrastructure line are provided for each segment. In this study, cumulative uncertainty is the summation of the georeferencing error of the utilized source imagery, one half of the pixel resolution of the source imagery, and the digitizing error. The National Oceanic Atmospheric Administration (NOAA) NGS imagery georeferencing error is represented by the horizontal error published with the source imagery. The Esri basemap imagery (collected by the North Carolina CGIA) georeferencing error was derived from 11 checkpoints in Onslow Bay, NC and 16 checkpoints in the Northern Outer Banks, NC that were recorded in 2019 and published in two different surveys: Stalk and others (2020); Brown and others (2021). The United States Department of Agriculture (USDA) NAIP imagery georeferencing errors were derived by comparing the positional offset of recognizable and discrete marks (such as tennis court, parking space, and crosswalks) on the ground between the Esri basemap (treated as a control) and NAIP imagery. Twenty-seven marks in Onslow Bay and 15 in the Northern Outer Banks were used for this purpose. NAIP imagery georeferencing errors are the positional offsets from the marks on the control, plus the georeferencing error of the Esri basemap imagery from the respective Onslow Bay or Northern Outer Banks region. The control points recorded in 2019 could not be used to measure the error of the NAIP imagery because not enough control points from the survey were visible in the NAIP imagery. Digitizing errors were derived by re-digitizing an additional first infrastructure line across 20.4 kilometers (km) on Oak Island, NC. The cross-shore distance between the original infrastructure line and the second infrastructure line was recorded at 10 meters (m) alongshore intervals. The digitizing error is the mean of the cross-shore distances recorded on these transects (0.99 m). All editing and calculations were conducted in ArcGIS Pro version 2.7. The final dataset is projected to the North American Datum of 1983 (NAD 1983) National Spatial Reference System (NSRS2007) Universal Transverse Mercator Zone 18 North (UTM 18N) coordinate system.

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Originator: North Carolina Center for Geographic Information and Analysis
Publication_Date: 20151113
Title: Imagery Hybrid
Publication_Information:

Publication_Place: ArcGIS Online
Publisher: Esri

Online_Linkage:

https://www.arcgis.com/home/item.html?id=28f49811a6974659988fd279de5ce39f

Type_of_Source_Media: raster digital data
Source_Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20200115
Ending_Date: 20210913

Source_Currentness_Reference: ground condition

Source_Citation_Abbreviation: Esri basemap
Source_Contribution:

Orthomosaics were used to reference the seaward boundary of the first infrastructure line during manual digitization, and to identify qualifying and non-qualifying structures.

Source_Information:

Source_Citation:

Citation_Information:

Originator:

United States Department of Agriculture National Agriculture Imagery Program

Publication_Date: 20191226
Title: 2018 North Carolina NAIP Digital Ortho Photo Imagery
Publication_Information:

Publication_Place: Charleston, SC
Publisher: NOAA

Online_Linkage: https://www.fisheries.noaa.gov/inport/item/58387

Type_of_Source_Media: raster digital data
Source_Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20180826
Ending_Date: 20181222

Source_Currentness_Reference: ground condition

Source_Citation_Abbreviation: USDA NAIP imagery
Source_Contribution:

Orthomosaics were used to reference the seaward boundary of the first infrastructure line during manual digitization, and to identify qualifying and non-qualifying structures.

Source_Information:

Source_Citation:

Citation_Information:

Originator:

National Oceanic and Atmospheric Administration National Geodetic Survey

Publication_Date: 202203
Title:

2020 NOAA NGS Ortho-rectified Color Mosaic Hurricane Florence: NC, SC, and VA

Publication_Information:

Publication_Place: Charleston, SC
Publisher: NOAA Office for Coastal Management, National Geodetic Survey

Online_Linkage: https://www.fisheries.noaa.gov/inport/item/66699

Type_of_Source_Media: raster digital data
Source_Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20200105
Ending_Date: 20200417

Source_Currentness_Reference: ground condition

Source_Citation_Abbreviation: NOAA NGS imagery
Source_Contribution:

Orthomosaics were used to reference the seaward boundary of the first infrastructure line during manual digitization, and to identify qualifying and non-qualifying structures.

Process_Step:

Process_Description:

Several sets of aerial and satellite imagery were used as a reference for this digitizing project, including imagery/orthomosaics from Esri, USDA NAIP, and NOAA NGS. Survey dates for the reference imagery range from 8/26/2018 to 9/13/2021. The imagery set used for a given reach of coast was determined by the available imageries’ perspective, published error, and pixel resolution. A purely nadir perspective (viewing angle directly perpendicular to the earth’s surface) of buildings, or an off-nadir viewing angle that allowed for the seaward facing side of a structure to be visible was required for an image to be used for digitization. Among images that satisfied this perspective requirement, imagery with more constrained horizontal errors and finer pixel resolutions were preferred.

Source_Used_Citation_Abbreviation: Esri basemap
Source_Used_Citation_Abbreviation: USDA NAIP imagery
Source_Used_Citation_Abbreviation: NOAA NGS imagery
Process_Date: 20211101
Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Alexander C. Seymour
Contact_Organization:

U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

Contact_Position: Physical Scientist
Contact_Address:

Address_Type: mailing and physical
Address: 600 4th Street South
City: Saint Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: United States

Contact_Voice_Telephone: 727-502-8122
Contact_Facsimile_Telephone: 727-502-8001
Contact_Electronic_Mail_Address: aseymour@usgs.gov

Process_Step:

Process_Description:

Digitization was conducted by a single researcher at 1:1,300 – 1:550 mapping scales in ArcGIS Pro version 2.7. The ArcGIS Pro editor toolbar was used to draw polylines alongshore. The first infrastructure line as defined in this dataset represents a cross-shore boundary where the most intense hold-the-line management actions are likely to be taken to prevent further landward transgression of the foredune. As such, digitization of this line required basic review of state statutes; in this case, the North Carolina Coastal Area Management Act of 1974 (North Carolina Department of Environmental Quality, 1974). According to North Carolina state statute, certain built structures can be classified as “threatened structures”, which can qualify them for elevated levels of protection including geotextile sandbag armoring. However, certain built features which often extend far seaward from primary residences and commercial buildings cannot be designated as “threatened structures”, including boardwalks, swimming pools, gazebos, and sheds. Thus, the aforementioned built features were ignored during digitization. This product was generated to facilitate calculation of coastal resilience metrics, specifically the distance between the dune crest and first infrastructure line. In some circumstances, limited, intermittent coastal retreat can occur among the line of first infrastructure, resulting in isolated clusters of buildings with more seaward positions than immediately adjacent dune crests. To ensure that dune crest/infrastructure distances derived from this data can be sensitive to this condition, we connected alongshore gaps in the first infrastructure line less than 200 m long. This produced negative infrastructure/dune crest distances, which may indicate areas where the primary foredune is infiltrating the first infrastructure line. For more information, please refer to Seymour and others (2026b).

Process_Date: 20211101
Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Alexander C. Seymour
Contact_Organization:

U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

Contact_Position: Physical Scientist
Contact_Address:

Address_Type: mailing and physical
Address: 600 4th Street South
City: Saint Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: United States

Contact_Voice_Telephone: 727-502-8122
Contact_Facsimile_Telephone: 727-502-8001
Contact_Electronic_Mail_Address: aseymour@usgs.gov

Process_Step:

Process_Description:

Uncertainty, source imagery, and state attributes were added to the attribute table of the digitized first infrastructure line segments using ArcGIS Pro's "Add Field" function and manual entry of values. ArcGIS Pro version 2.7 was used for these processes.

Process_Date: 20221219
Source_Produced_Citation_Abbreviation: NC_First_Infrastructure_Line.shp
Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Alexander C. Seymour
Contact_Organization:

U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

Contact_Position: Physical Scientist
Contact_Address:

Address_Type: mailing and physical
Address: 600 4th Street South
City: Saint Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: United States

Contact_Voice_Telephone: 727-502-8122
Contact_Facsimile_Telephone: 727-502-8001
Contact_Electronic_Mail_Address: aseymour@usgs.gov

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Vector
Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type: String
Point_and_Vector_Object_Count: 44

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Grid_Coordinate_System:

Grid_Coordinate_System_Name: Universal Transverse Mercator
Universal_Transverse_Mercator:

UTM_Zone_Number: 18N
Transverse_Mercator:

Scale_Factor_at_Central_Meridian: 0.9996
Longitude_of_Central_Meridian: -75.0
Latitude_of_Projection_Origin: 0.0
False_Easting: 500000.0
False_Northing: 0.0

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:

Abscissa_Resolution: 0.001
Ordinate_Resolution: 0.001

Planar_Distance_Units: meters

Geodetic_Model:

Horizontal_Datum_Name: NAD 1983 (NSRS2007)
Ellipsoid_Name: GRS 1980
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257222101

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: NC_First_Infrastructure_Line.shp
Entity_Type_Definition:

Polyline shapefile of the first infrastructure line for North Carolina.

Entity_Type_Definition_Source: USGS

Attribute:

Attribute_Label: FID
Attribute_Definition: Internal feature number.
Attribute_Definition_Source: Esri
Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: Shape
Attribute_Definition: Feature geometry.
Attribute_Definition_Source: Esri
Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: Shape_Leng
Attribute_Definition: Length of line segment, in meters.
Attribute_Definition_Source: Esri
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 155.610335
Range_Domain_Maximum: 45904.093541

Attribute:

Attribute_Label: Segment
Attribute_Definition:

First infrastructure line segment identification number, ordered from north to south.

Attribute_Definition_Source: USGS
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 44

Attribute:

Attribute_Label: Source_Img
Attribute_Definition:

Character string representing the publisher of the imagery sources used to digitize the first infrastructure line on a given segment. If multiple sources were used, each were separated by a comma.

Attribute_Definition_Source: USGS
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: ESRI
Enumerated_Domain_Value_Definition:

Esri basemap imagery was used to digitize the first infrastructure line segment.

Enumerated_Domain_Value_Definition_Source: USGS

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: USDA
Enumerated_Domain_Value_Definition:

USDA NAIP imagery was used to digitize the first infrastructure line segment.

Enumerated_Domain_Value_Definition_Source: USGS

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: NGS
Enumerated_Domain_Value_Definition:

NOAA NGS imagery used to digitize the first infrastructure line segment.

Enumerated_Domain_Value_Definition_Source: USGS

Attribute:

Attribute_Label: State
Attribute_Definition:

Character string representing the state where the segment is found.

Attribute_Definition_Source: USGS
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: North Carolina
Enumerated_Domain_Value_Definition: The state where the segment is located.
Enumerated_Domain_Value_Definition_Source: USGS

Attribute:

Attribute_Label: Uncy
Attribute_Definition:

A string representing the cross-shore positional uncertainty of the first infrastructure line, in meters. An uncertainty is provided for each imagery source used on a given segment.

Attribute_Definition_Source: USGS
Attribute_Domain_Values:

Unrepresentable_Domain:

The uncertainty for each source image used separated by a comma. The order of the provided uncertainties follows the order of the source images listed in the Source_Img attribute.

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center

Contact_Person: USGS SPCMSC Data Management

Contact_Address:

Address_Type: mailing and physical
Address: 600 4th Street South
City: Saint Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: United States

Contact_Voice_Telephone: 727-502-8000
Contact_Electronic_Mail_Address: gs-g-spcmsc_data_inquiries@usgs.gov

Resource_Description: NC_First_Infrastructure_Line.shp
Distribution_Liability:

Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), and have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: shapefile
File_Decompression_Technique:

The data download file is compressed and must be unzipped using software such as WinZip, 7Zip, etc. before use.

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name:

https://coastal.er.usgs.gov/data-release/doi-P9GL68X8/data/NC_First_Infrastructure_Line.zip

Access_Instructions: None

Fees: None

Metadata_Reference_Information:

Metadata_Date: 20260310
Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center

Contact_Person: USGS SPCMSC Data Management

Contact_Address:

Address_Type: mailing and physical
Address: 600 4th Street South
City: Saint Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: United States

Contact_Voice_Telephone: 727-502-8000
Contact_Electronic_Mail_Address: gs-g-spcmsc_data_inquiries@usgs.gov

Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time

This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/NC_First_Infrastructure_Line_metadata.html>