There are critical needs for a nationwide compilation of reliable shoreline data. To meet these needs, the USGS has produced a comprehensive database of digital vector shorelines by compiling shoreline positions from pre-existing historical shoreline databases and by generating historical and modern shoreline data. Shorelines are compiled by state and generally correspond to one of four time periods: 1800s, 1920s-1930s, 1970s, and 1998-2002. Each shoreline may represent a compilation of data from one or more sources for one or more dates provided by one or more agencies. Details regarding source are provided in the 'Data Quality Information' section of this metadata report. Shoreline vectors derived from historic sources (first three time periods) represent the high water line at the time of the survey, whereas modern shorelines (final time period) represent the mean high water line.
Historical shoreline change is considered to be a crucial element in studying the vulnerability of the national shoreline. These data are used in a shoreline change analysis for the USGS National Assessment Project.
ground condition
This data set is not to be used for navigational purposes. 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.
400 Natural Bridges Drive
There is significant agreement of linework between adjacent shorelines. Shorelines were checked for accuracy, but no edgematching attempts were made between adjacent shorelines even if slight offsets existed.
This shoreline data adequately represented the shoreline at the time of the survey. Remaining gaps in this data, if applicable, are a consequence of non-existing data or existing data that did not meet quality assurance standards.
The maximum estimated positional error for this shoreline is 13.9 meters. Please visit our full report on shoreline change in the Coastline of California (http://pubs.usgs.gov/of/2006/1219/), under the heading 'Uncertainties and Errors', for a complete explanation of the measurement error.
NOAA NOS Topographic Sheets (t-sheet or tp-sheet maps)
Shorelines from one or more sources were sought in an effort to develop a single shoreline for each time period. Digital shorelines, if available from another agency, were acquired. If no digital shorelines were available or if a data set was incomplete, T-sheets were requested from NOAA and received as scanned raster images. T-sheets were geo-registered using ERDAS Imagine geographic imaging software by placing 6-10 well-spaced ground control points at gridline intersections. Some T-sheets may have required additional coordinate transformation information from NOAA to account for datum offsets between historical datums (USSD) and modern datums (NAD27 or NAD83). Datum transformations were applied to GCP coordinates prior to registration. Total RMS error for the rectification process was maintained below 1 pixel, which translates to approximately 4m at a scale of 1:20,000 and 1.5m at a scale of 1:10,000. Geo-registered T-sheets were loaded in ArcView and vector shorelines were digitized. Quality assessments were performed and shorelines were edited to remove any overlap between adjacent shorelines. No edgematching between adjacent shorelines was attempted. Finally, shorelines from all sources were merged to produce a single shoreline for the period. The final shoreline was coded with 6 attribute fields (ID, Type, Date, Descr, Source, and Accuracy) required for the Digital Shoreline Analysis System (DSAS), which was used to calculate shoreline change rates. The attributes reflect the source of the data and the original survey year.
400 Natural Bridges Drive
Data were projected from UTM zone 10 to geographic with a datum shift from NAD27 to NAD83 Tool: ArcGIS > ArcToolbox > Toolboxes > Data Management Tools > Project Command issued: GEOGCS['GCS_North_American_1983',DATUM['D_North_American_1983',SPHEROID['GRS_1980',6378137.0,298.257222101]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]] # NAD_1927_To_NAD_1983_NADCON
384 Woods Hole Road
Internal feature number.
ESRI
Feature geometry.
ESRI
Feature number.
U.S. Geological Survey
Type of feature.
U.S. Geological Survey
Vector shoreline.
U.S. Geological Survey
Detailed description of the feature.
U.S. Geological Survey
Agency that provided feature or data used to create feature.
U.S. Geological Survey
NOAA
U.S. Geological Survey
Position accuracy of feature.
U.S. Geological Survey
Date of Shoreline Segment
USGS
NOS T-Sheet Dates
NOAA NOS T-Sheets
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
Seven files comprise the ArcView shapefile: <filename>.dbf, <filename>.shp, <filename>.shx, <filename>.prj, <filename>.avl, <filename>.sbx, <filename>.sbn
400 Natural Bridges Drive