Rates of cliff erosion were generated in a GIS using the Digital Shoreline Analysis System (DSAS) version 3.0; An ArcGIS extension for calculating shoreline change: U.S. Geological Survey Open-File Report 2005-1304, Thieler, E.R., Himmelstoss, E.A., Zichichi, J.L., and Miller, T.M. The extension is designed to efficiently lead a user through the major steps of shoreline change analysis. This extension to ArcGIS contains three main components that define a baseline, generate orthogonal transects at a user-defined separation along the coast, and calculate rates of change (linear regression, endpoint rate, average of rates, average of endpoints, jackknife).
Historical cliff erosion is considered to be a crucial element in studying the vulnerability of the national coastline. These data are used in a cliff erosion analysis for the USGS National Assessment Project.
publication date
Public domain data from the U.S. government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
USGS Patuxent Wildlife Research Center
University of Rhode Island
317 Woodward Hall, Dept. of Geosciences
The attributes in this dataset are based on the Digital Shoreline Analysis System (DSAS) version 3.2; An ArcGIS extension for calculating shoreline change (Thieler, E.R., Himmelstoss, E.A., Zichichi, J.L., and Miller, T.M. 2005. U.S. Geological Survey Open-File Report 2005-1304). The data has gone through a series of QA/QC procedures, and is therefore believed to accurately reflect the data gathered as part of the National Assessment of Shoreline Change Study.
Transect generation was made as part of the calculation process for the Digital Shoreline Analysis System an Extension for ArcGIS (http://pubs.usgs.gov/of/2005/1304/). No additional checks for topological consistency were performed on the data.
This cliff edge-transect data adequately represented the intersect at the time of the analysis. Remaining gaps in this data, if applicable, are a consequence of non-existing data, transects crossing man-made features or existing data that did not meet quality assurance standards.
Postional Accuracy is based on position of shoreline with respect to the transect.
A baseline was manually constructed seaward of, and parallel to, the trend of shorelines representing four general time periods (1800s, 1920s-1930s, 1970s, and 1998-2002). Using DSAS an Extension for ArcGIS (http://pubs.usgs.gov/of/2005/1304/), transects were generated with a spacing of 50m and transect-shoreline intersection points were saved to a separate layer. Transects were manually eliminated to prevent calculation of rates in areas where less than four shorelines were intersected. Long-term rates of shoreline change, in units of m/yr, were calculated at each transect using linear regression applied to all four shoreline positions from the earliest (1800s) to the most recent (derived from lidar). Linear regression was selected because it has been shown to be the most statistically robust quantitative method when a limited number of shorelines are available and it is the most commonly applied statistical technique for expressing shoreline movement and estimating rates of change. Uncertainties for the long-term rates are also reported in units of m/yr and represent a 90% confidence interval for the slope of the regression line. This means with 90% statistical confidence that the true rate of shoreline change falls within the range defined by the reported value plus or minus the error value. The variability around the trend reflects both measurement and sampling errors. Short-term rates of shoreline change, in units of m/yr, were calculated using the endpoint method comparing the 1970s and most recent shoreline positions.
USGS Patuxent Wildlife Research Center
University of Rhode Island
Coastal Field Station
317 Woodward Hall, Dept. of Geosciences
Data were projected from UTM zone 10 to geographic Tool: ArcGIS > ArcToolbox > Toolboxes > Data Management Tools > Project Command issued: ['GCS_North_American_1983',DATUM['D_North_American_1983',SHPERIOD['GRS_1980',6378137.0,298.25722101]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]
384 Woods Hole Road
Internal feature number
ESRI
Feature geometry
U.S. Geological Survey
The object identifier value of the transect in the transect attribute table, identifies transect with which the intersection points are associated.
U.S. Geological Survey
Identifies which baseline the transect was cast from based on the baseline ID field. Useful when multiple baseline segments exist, baseline ID used by Transect.
U.S. Geological Survey
Identifies which shoreline the transect is intersecting.
U.S. Geological Survey
The transect length betwee the identified baseline and shoreline, distance from Baseline to Shoreline-Transect Intersect
U.S. Geological Survey
The y-coordinate for the location point of the shoreline/transect intersection.
U.S. Geological Survey
The x-coordinate for the location point of the shoreline/transect intersection.
U.S. Geological Survey
Pacific Science Center
400 Natural Bridges Drive
Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, these data and information are provided with the understanding that they are not guaranteed to be usable, timely, accurate, or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user. Neither the U.S. Government nor any agency thereof, 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 data, software, information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. Trade, firm, or product names and other references to non-USGS products and services are provided for information only and do not constitute endorsement or warranty, express or implied, by the USGS, USDOI, or U.S. Government, as to their suitability, content, usefulness, functioning, completeness, or accuracy.
ESRI Polyline Shapefile. The DBF file contains the attribute data in dBASE format. The PRJ file contains the coordinate system information. The SBN and SBX files contain the spatial index of the geospatial data. The SHP file contains the geospatial data. The SHX file contains the index of the geospatial data. The XML file contains the metadata describing the data set.
USGS Patuxent Wildlife Research Center
University of Rhode Island
Coastal Field Station
317 Woodward Hall, Dept. of Geosciences