SOCAL_BIASVALUES - Southern California Shoreline Bias Values

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Frequently anticipated questions:


What does this data set describe?

Title: SOCAL_BIASVALUES - Southern California Shoreline Bias Values
Abstract:
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. These shorelines were used to calculate long-term and short-term change rates 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. Shoreline vectors derived from historic sources (first three time periods) represent the high water line (HWL) at the time of the survey, whereas modern shorelines (final time period) represent the mean high water line (MHW). Changing the shoreline definition from a proxy-based physical feature that is uncontrolled in terms of an elevation datum (HWL) to a datum-based shoreline defined by an elevation contour (MHW) has important implications with regard to inferred changes in shoreline position and calculated rates of change. This proxy-datum offset is particularly important when averaging shoreline change rates alongshore. Since the proxy-datum offset is a bias, virtually always acting in the same direction, the error associated with the apparent shoreline change rate shift does not cancel during averaging and it is important to quantify the bias in order to account for the rate shift. The shoreline change rates presented in this report have been calculated by accounting for the proxy-datum bias.
  1. How might this data set be cited?
    Hapke, Cheryl, and Reid, David, 2006, SOCAL_BIASVALUES - Southern California Shoreline Bias Values: Open-File Report 2006-1251, U.S. Geological Survey, Coastal and Marine Geology Program, Pacific Science Center, Santa Cruz, CA.

    Online Links:

    This is part of the following larger work.

    Hapke, Cheryl, and Reid, David, 2006, National Assessment of Shoreline Change: A GIS Compilation of Vector Shorelines and Associated Shoreline Change Data for the Sandy Shorelines of the California Coast: Open-File Report 2006-1251, U.S. Geological Survey, Coastal and Marine Geology Program, Pacific Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -119.998365
    East_Bounding_Coordinate: -117.131602
    North_Bounding_Coordinate: 34.456515
    South_Bounding_Coordinate: 32.576153
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2006
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • String (15527)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000000. Longitudes are given to the nearest 0.000000. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.
  7. How does the data set describe geographic features?
    Socal_BiasValues
    Bias Uncertainty Values (Source: USGS)
    FID
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: ESRI) Coordinates defining the features.
    ID
    Feature number. (Source: U.S. Geological Survey) Sequential Numbers defining the features.
    DESCR
    Detailed description of the feature. (Source: U.S. Geological Survey) Describes additional characteristics of feature.
    BIAS
    Shoreline Bias Value (Source: USGS)
    Range of values
    Minimum:10.1
    Maximum:24.2
    Units:meters
    Resolution:0.1
    LT_MAXMIN
    ST_MAXMIN
    LT_MaxMin
    Long-Term Bias Uncertainty (Source: USGS)
    Range of values
    Minimum:5.7
    Maximum:15.9
    Units:meters
    Resolution:0.1
    ST_MaxMin
    Short Term Bias Uncertainty (Source: USGS)
    Range of values
    Minimum:9.9
    Maximum:27.5
    Units:meters
    Resolution:0.1

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Cheryl Hapke
    • David Reid
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Science Center
    400 Natural Briges Drive
    Santa Cruz, Ca
    USA

    (831) 427-4450 (voice)
    (831) 427-4748 (FAX)
    Hours_of_Service: Monday through Friday, 8 a.m. to 5 p.m., Eastern Standard Time

Why was the data set created?

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.

How was the data set created?

  1. From what previous works were the data drawn?
    (source 1 of 1)
    ,.

    This is part of the following larger work.

    ,.

  2. How were the data generated, processed, and modified?
    (process 1 of 4)
    In order to calculate the bias, as well as the bias uncertainty, for this regional shoreline change analysis, long-term best estimates and measures of uncertainty are derived for beach slope, wave height, wave length, and tide level. The best estimate for beach slope was derived by averaging individual lidar transect slope estimates within 1-km blocks along the coast. We take the long-term mean wave height and length to be the best estimate to use in the bias calculation. The long-term mean wave height is derived from USACOE Wave Information Studies (WIS) hindcasts while the long-term mean wave length is derived from long-term buoy records (NDBC and CDIP) along the California Coast. Finally, the best estimate of the tide level responsible for generating HWL shorelines is taken as the elevation of MHW. The measures of uncertainty for the beach slope, wave height, and wave length are estimated as the difference between the 95% exceedance statistic and the 50% exceedance statistic of the cumulative distributions. This gives a 90% confidence interval on each of the cumulative distributions. The uncertainty of assuming that the tide responsible for leaving HWL-type shorelines was at MHW is calculated simply by MHHW-MHW. The proxy-datum bias, and the associated uncertainty, is calculated at each of the 1-km blocks in which the average beach slope has been calculated. The nearest WIS station, wave buoy, and tide gage to each individual 1-km block were used in the application of Equation 1. Once the bias was calculated, it was incorporated into DSAS and applied on a transect-by-transect basis, so that the estimated bias is removed from the final long- and short-term shoreline change rates. The bias, averaged over 815 1-km sections of the California coast, was approximately 18 m with an average uncertainty of approximately 8.7m. Please See Below References for More information about the procedure:
    Ruggiero, P., Kaminsky, G.M., and Gelfenbaum, G., 2003, Linking proxy-based and datum-based shorelines on a high-energy coastline: Implications for shoreline change analyses: Journal of Coastal Research Special Issue 38, p. 57-82.
    Moore, L.J., Ruggiero, P.R. and List, J., 2006. Comparing high water line and datum-based shorelines: Implications for shoreline change. Journal of Coastal Research, v.22, n.4, pp. 894-905. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Bruce Richmond
    400 Natural Bridges Drive
    Santa Cruz, Ca
    USA

    (831) 427-4450 (voice)
    (831) 427-4748 (FAX)
    Hours_of_Service: Monday through Friday, 8 a.m. to 5 p.m., Pacific Standard Time
    Date: 15-Feb-2007 (process 2 of 4)
    Data were projected from UTM zone 10 to geographic with Datum shift from NAD27 to NAD83_6
    Tool: ArcGIS > ArcToolbox > Toolboxes > Data Management Tools > Project
    Command issued:
    ['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_6 Person who carried out this activity:
    Emily Himmelstoss
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2262 (voice)
    (508) 457-2310 (FAX)
    ehimmelstoss@usgs.gov
    Date: 07-Feb-2017 (process 3 of 4)
    Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
    Date: 26-Apr-2018 (process 4 of 4)
    Added keywords from Coastal and Marine Ecological Classification Standard (CMECS) to metadata. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
  3. What similar or related data should the user be aware of?
    Hapke, Cheryl J., Reid, David, Richmond, Bruce M., Ruggiero, Peter, and List, Jeff, 2006, National Assessment of Shoreline Change Part 3: Historical Shoreline Change and Associated Coastal Land Loss Along Sandy Shorelines of the California Coast: Open-File Report 2006-1219, U.S. Geological Survey, Coastal and Marine Geology Program, Pacific Science Center, Santa Cruz, CA.

    Online Links:

    Thieler, E. Robert, Himmelstoss, Emily A., Zichichi, Jessica L., and Miller, Tara L., 2005, The Digital Shoreline Analysis System (DSAS) version 3.0, an ArcGIS Extension for Calculating Historic Shoreline Change: Open-File Report 2005-1304, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Moore, Laura, Ruggiero, Peter, and List, Jeff, 2006, Comparing mean high water and high water line shorelines: Should proxy-datum offsets be incorporated in shoreline change analysis.: Journal of Coastal Research v.22, n.4, pp. 894-905, Coastal Education and Research Foundation, Royal Palm Beach, FL.


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    The bias uncertainty, averaged over 815 1-km sections of the California coast, was approximately 18 m with an average uncertainty of approximately 8.7m. Please see the Open File Report for more information (http://pubs.usgs.gov/of/2006/1219/)
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    The bias, averaged over 815 1-km sections of the California coast, was approximately 18 m with an average uncertainty of approximately 8.7m.
  5. How consistent are the relationships among the observations, including topology?
    The proxy-datum bias, and the associated uncertainty, is calculated at each of the 1-km blocks in which the average beach slope has been calculated. The nearest WIS station, wave buoy, and tide gage to each individual 1-km block were used in the application of Equation 1. Once the bias was calculated, it was incorporated into DSAS and applied on a transect-by-transect basis, so that the estimated bias is removed from the final long- and short-term shoreline change rates.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
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.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Pacific Science Center
    Santa Cruz, Ca
    USA

    (831) 427-4450 (voice)
    (831) 427-4748 (FAX)
    Hours_of_Service: Monday through Friday, 8 a.m. to 5 p.m., Eastern Standard Time
  2. What's the catalog number I need to order this data set? Downloadable Data: USGS Open-File Report 2006-1251
  3. What legal disclaimers am I supposed to read?
    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.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data are available in Environmental Systems Research Institute (ESRI) shapefile format. The user must have ArcGIS or ArcView 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing the data. A free data viewer, ArcExplorer, capable of displaying the data is available from ESRI at www.esri.com.

Who wrote the metadata?

Dates:
Last modified: 26-Apr-2018
Metadata author:
U.S. Geological Survey
Pacific Science Center
Santa Cruz, Ca
USA

(831) 427-4450 (voice)
(831) 427-4748 (FAX)
Hours_of_Service: Monday through Friday, 8 a.m. to 5 p.m., Eastern Standard Time
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/westcoast/shoreline_change/ca_coast/socal_biasvalues.shp.faq.html>
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