Baseline for the Virginia coastal region, generated to calculate shoreline change rates using the Digital Shoreline Analysis System version 5.1
The U.S. Geological Survey (USGS) has compiled national shoreline data for more than 20 years to document coastal change and serve the needs of research, management, and the public. Maintaining a record of historical shoreline positions is an effective method to monitor national shoreline evolution over time, enabling scientists to identify areas most susceptible to erosion or accretion. These data can help coastal managers and planners understand which areas of the coast are vulnerable to change.
This data release includes a compilation of previously published historical shoreline positions for Virginia spanning 148 years (1849-1997), and two new mean high water (MHW) shorelines extracted from lidar data collected in 2010 and 2017. These data provide a standardized shoreline database for the state. This release includes both long-term (up to 168 years) and short term (~20 years) rates. Files associated with the long-term and short-term rates are appended with "LT" and "ST", respectively. A proxy-datum bias reference line that accounts for the positional difference in a proxy shoreline (e.g. High Water Line (HWL) shoreline) and a datum shoreline (e.g. MHW shoreline) is also included in this release.
Bartlett, Marie K., 20230526, Baseline for the Virginia coastal region, generated to calculate shoreline change rates using the Digital Shoreline Analysis System version 5.1: data release DOI:10.5066/P9DHOFXU, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.
Bartlett, Marie K., Henderson, Rachel E., and Farris, Amy S., 2023, USGS National Shoreline Change — A GIS Compilation of Vector Shorelines and Associated Shoreline Change Data for Coastal Virginia from the 1840s to 2010s: data release DOI:10.5066/P9DHOFXU, U.S. Geological Survey, Reston, VA.
Bartlett, M.K., Henderson R.E., and Farris, A.S., 2023, USGS National Shoreline Change - A GIS compilation of vector shorelines and associated shoreline change data for coastal Virginia from the 1840s to 2010s: U.S. Geological Survey data release, https://doi.org/10.5066/P9DHOFXU.
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest 0.6096
Ordinates (y-coordinates) are specified to the nearest 0.6096
Planar coordinates are specified in meters
The horizontal datum used is WGS_1984.
The ellipsoid used is WGS_84.
The semi-major axis of the ellipsoid used is 6378137.0.
The flattening of the ellipsoid used is 1/298.257223563.
Reference baseline used by the Digital Shoreline Analysis System (DSAS) to calculate rate-of-change statistics.
(Source: U.S. Geological Survey (USGS))
Internal feature number.
Sequential unique whole numbers that are automatically generated.
Feature geometry. The baseline is a polyline shapefile.
Field required by the Digital Shoreline Analysis System (DSAS) software. This field is manually edited to ensure baseline segment numbers occur in sequential order alongshore. DSAS uses this value to determine the ordering sequence of transects when the baseline feature contains multiple segments.
Range of values
This optional field is a way to aggregate baseline segments on the basis of physical variations alongshore (for example, tidal inlets, change in coastal type, or hard stabilization features). Baseline segments are sorted into groups and the groups are assigned an ID value. Statistics are reported by group in the DSAS summary text file once rates are calculated.
Range of values
The search distance field is an optional field that represents the (user defined) distance, in meters, that DSAS will use to search for shorelines, extending out from either side of the baseline. The distance value can be unique for each baseline segment depending on the organization of shorelines with respect to the baseline. Values populated in this field will override the "Maximum Search Distance From Baseline" value entered in Cast Transects settings.
Range of values
Length of feature in meter units.
Range of values
The entity and attribute information provided here describes the tabular data associated with the dataset. Please review the individual attribute descriptions for detailed information.
This dataset includes a reference baseline used by the Digital Shoreline Analysis System (DSAS) to calculate rate-of-change statistics. This baseline layer serves as the starting point for orthogonally-oriented transects generated by the DSAS application. The transects intersect each shoreline and establish measurement points used to calculate shoreline change rates.
A polyline, midshore baseline was constructed using standard feature creation tools in Esri's ArcMap v10.7.1. The baseline was positioned to follow the overall orientation of the shorelines alongshore. This was done so that the transects, which are generated by the DSAS software and extend from the baseline, would intersect roughly perpendicular to the general trend of the shorelines. The baseline was constructed in UTM Zone 18N (WGS 84) coordinate system. This process step and all subsequent process steps were performed by the same person - Marie K. Bartlett
Person who carried out this activity:
Marie K. Bartlett
U.S. Geological Survey
384 Woods Hole Road
Woods Hole, MA
508-548-8700 x 2306 (voice)
Date: 2022 (process 2 of 4)
The baseline feature class was imported into a personal geodatabase in ArcCatalog v10.7.1 by right-clicking on the geodatabase > Import for use as the input within the Digital Shoreline Analysis System (DSAS) v.5.1 software to generate transects and perform rate calculations.
Date: 2022 (process 3 of 4)
Required fields for DSAS were added using the DSAS Attribute Automator tool. These fields include ID, and DSAS_group. The baseline feature class was used along with the shorelines file (see larger work citation, VA_Shorelines.shp) as the input within the Digital Shoreline Analysis System (DSAS) software to generate transects and perform rate calculations.
Date: 2022 (process 4 of 4)
The baseline feature class was exported from a personal geodatabase to a shapefile in ArcCatalog v10.7.1 for publication by right-clicking on the data layer > Export > To shapefile (single).
Himmelstoss, Emily A., Farris, Amy S., Henderson, Rachel E., Kratzmann, Meredith G., Ergul, Ayhan, Zhang, Ouya, Zichichi, Jessica L., and Thieler, E. Robert, 2018, Digital Shoreline Analysis System (version 5.1): U.S. Geological Survey Software: software release version 5.1, U.S. Geological Survey, Reston, VA.
Use the first two links to access the software. The third link directs to the DSAS project page. Current software at time of use was 5.1.
Himmelstoss, Emily A., Henderson, Rachel E., Kratzmann, Meredith G., and Farris, Amy S., 20211019, Digital Shoreline Analysis System (version 5.1) User Guide: Open-File Report 2021-1091, U.S. Geological Survey, Reston, VA.
Use the first two access the user guide. The third link directs to the DSAS project page.
Ruggiero, Peter, and List, Jeffrey H., 200909, Improving Accuracy and Statistical Reliability of Shoreline Position and Change Rate Estimates: Journal of Coastal Research vol. 255, Coastal Education and Research Foundation, n/a.
How accurate are the geographic locations?
The baseline serves as a reference point for transects cast by the Digital Shoreline Analysis System (DSAS) software. It does not correspond to any real-world feature.
Where are the gaps in the data? What is missing?
This baseline file is complete and contains the baseline segment(s) used to cast transects along sections of the coastal region where shoreline position data were available to calculate either a short- or long-term rate.
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset. These data are not to be used for navigation.
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.
These files (.cpg, .dbf, .prj, .sbn, .sbx, .shp, and .shx) are a collection of files with a common filename prefix and must be downloaded and stored in the same directory. Together they are the components of the shapefile. Additional files of the same name included are FGDC CSDGM-compliant metadata in XML format.
in format Shapefile
(version ArcGIS 10.7.1)
Esri polyline shapefile