There are critical needs for a nationwide compilation of reliable shoreline data. To meet these needs, the U.S. Geological Survey (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.
ground condition
Vector Shoreline from Lidar Overflight(Source:
USGS)
Internal feature number.(Source:
ESRI)
Position accuracy of feature.(Source:
U.S. Geological Survey)
| Value | Definition |
|---|---|
| 0 |
The accuracy is not given or is not known. |
Feature geometry.(Source:
ESRI)
Feature number.(Source:
U.S. Geological Survey)
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 40677 |
Type of feature.(Source:
U.S. Geological Survey)
| Value | Definition |
|---|---|
| Shoreline |
Vector shoreline. |
Detailed description of the feature.(Source:
U.S. Geological Survey)
Agency that provided feature or data used to create feature.(Source:
U.S. Geological Survey)
Date of Lidar Over Flight(Source:
USGS)
Pacific Science Center
400 Natural Bridges Drive
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 U.S. Geological Survey (USGS) National Assessment Project.
USGS/NASA Airborne Topographic Mapper
The USGS in collaboration with NASA, used the NASA Airborne Topographic Mapper (ATM II and III) mounted on a Twin Otter Aircraft to map coastal beaches. The raw data was georeferenced at elevation points every few square meters. The original data from ATM was collected in WGS 84, ITRF 97, in a geographic (lat/long) coordinate system with irregular spacing. The data was then converted to NAD 83 and NAVD 88. The shoreline generation involved an analysis of shore-normal profiles at 20m intervals alongshore. First, a shore-parallel reference line was digitized as a permanent baseline for any future shoreline generation. Profiles were assessed at 20m intervals perpendicular to the reference line. Each profile consisted of a 4m wide swath of data points. An algorithm determined the shoreline position for each profile based on a regression fit through the foreshore of the profile. The function was evaluated at the mean high water (mhw) level to identify the horizontal position of the shoreline. Results were only accepted if the R-squared value of the regression was significant to the 95% confidence level. The shoreline point solutions were then quality checked in ArcView GIS software against a gray scale elevation grid of the same data. Point solutions were connected to produce a continuous vector shoreline in shapefile format.
Pacific Science Center
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
The maximum positional error for this shoreline, considered independently, is 1.5m. However, if the lidar mean high water shoreline (mhwl) is used for comparison with other high water shorelines (hwl), an additional shoreline proxy offset must be considered. When the offset error is considered, as it pertains to lidar shorelines of the coastline of California, it varies based on beach slope, wave height, wave length, and tide level. Calculations of these parameters along the open coastline of California were made in order to quantify this bias offset. Please visit our full report on shoreline change along the sandy shoreline of the coast of California (http://pubs.usgs.gov/of/2006/1219/), under the heading 'Uncertainties and Errors', for a complete explanation of the measurement error.
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.
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 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.
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.
Data format: |
in format SHP
(version 20060901) Seven files comprise the ArcView shapefile: <filename>.dbf, <filename>.shp, <filename>.shx, <filename>.prj, <filename>.avl, <filename>.sbx, <filename>.sbnSize: 0.678 |
|---|---|
Network links: |
http://pubs.usgs.gov/of/2006/1251/NCal.zip
http://pubs.usgs.gov/of/2006/1251/#gis |
Pacific Science Center
400 Natural Bridges Drive