Mean high water (MHW) shorelines along the coast of California used to calculated shoreline change from 1998 to 2016

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Frequently anticipated questions:

What does this data set describe?

Title:
Mean high water (MHW) shorelines along the coast of California used to calculated shoreline change from 1998 to 2016
Abstract:
This dataset contains mean high water (MHW) shorelines for sandy beaches along the coast of California for the years 1998/2002, 2015, and 2016. The MHW elevation in each analysis region (Northern, Central, and Southern California) maintained consistency with that of the National Assessment of Shoreline Change. The operational MHW line was extracted from Light Detection and Ranging (LiDAR) digital elevation models (DEMs) using the ArcGIS smoothed contour method. The smoothed contour line was then quality controlled to remove artifacts, as well as remove any contour tool interpretation of human-made infrastructure (such as jetties, piers, and sea walls), using satellite imagery from ArcGIS.
Supplemental_Information:
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Barnard, Patrick L., Smith, Schuyler A., and Foxgrover, Amy C., 20201231, Mean high water (MHW) shorelines along the coast of California used to calculated shoreline change from 1998 to 2016: data release DOI:10.5066/P91QSGXF, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Barnard, Patrick L., Smith, Schuyler A., and Foxgrover, Amy C., 2020, California shorelines and shoreline change data, 1998-2016: data release DOI:10.5066/P91QSGXF, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -114.14
    East_Bounding_Coordinate: -124.42
    North_Bounding_Coordinate: 42.00
    South_Bounding_Coordinate: 32.53
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 18-Apr-1998
    Ending_Date: 01-May-2016
    Currentness_Reference:
    Dates of datasets used in the analysis
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: polyline shapefiles
  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.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -123.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 2.000000
      Ordinates (y-coordinates) are specified to the nearest 2.000000
      Planar coordinates are specified in meters
      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?
    California shorelines for the years 1998/2002, 2015, and 2016
    Shapefiles consisting of shoreline position, defined by MHW, for discrete years and regions of the state: Northern California (NorCal), Central California (CenCal), and Southern California (SoCal). (Source: originators at United States Geological Survey, Pacific Coastal and Marine Science Center)
    Date
    Effective date of MHW shoreline location from all contributing data (Source: producer defined)
    Range of values
    Minimum:4/18/98
    Maximum:5/1/16
    Units:month/day/year
    Uncert
    Horizontal uncertainty of shoreline location (Source: producer defined)
    Range of values
    Minimum:0.28
    Maximum:4.35
    Units:meters

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Patrick L. Barnard
    • Schuyler A. Smith
    • Amy C. Foxgrover
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, California
    USA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

This work is one portion of ongoing coastal monitoring efforts for California and the western United States. These data provide an estimate of past shoreline positions and shoreline change throughout California, with the goal of understanding how shorelines change over time and in response to El Nino events. The data are intended for policy makers, resource managers, science researchers, students, and the general public. These data can be used with geographic information systems or other software to identify and assess possible areas of vulnerability. These data are not intended to be used for navigation.

How was the data set created?

  1. From what previous works were the data drawn?
    NOAA LiDAR (source 1 of 2)
    National Oceanic and Atmospheric Administration (NOAA), 2016, NOAA LiDAR surveys of the Central California region 1998-2016: NOAA Digital Coast, online.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    MHW shoreline positions were digitized from multiple LiDAR data sets within the full geographic extent of the study area from 1998 - 2016.
    SoCal LiDAR (source 2 of 2)
    Data from Southern California Coastal Response to 2015-2016 El Nino, 2018, Data from Southern California Coastal Response to the 2015-2016 El Nino: University of California San Diego Library Digital Collection, online.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    Using ArcGIS, MHW shorelines were extracted from these airborne LiDAR datasets collected on 6-October-2015 and 22-March-2016.
  2. How were the data generated, processed, and modified?
    Date: 01-Jul-2017 (process 1 of 4)
    High-accuracy LiDAR data were downloaded from NOAA Digital Coast in the form of digital elevation models (DEMs) for both pre-El Nino (2015) and post-El Nino (2016), as well as 1998/2002 for perspective. Due to sparse LiDAR data coverage in southern California, SoCal LiDAR from UC San Diego Library Collections was used in this region. Data sources used in this process:
    • NOAA LiDAR
    • SoCal LiDAR
    Date: 15-Aug-2017 (process 2 of 4)
    The operational MHW line was extracted using the ArcGIS smoothed contour method with the smoothing tolerance parameter set to 30 m alongshore. The NAVD88 datum was used for the MHW elevation. The mean high water (MHW) shoreline elevation in each analysis region (Northern, Central, and Southern California) maintained consistency with that of the National Assessment of Shoreline Change.
    Date: 01-Apr-2018 (process 3 of 4)
    The smoothed contour line was then quality controlled to remove artifacts, as well as remove any contour tool interpretation of human-made infrastructure (such as jetties, piers, and sea walls), using satellite imagery available in ArcGIS.
    Date: 15-Jun-2018 (process 4 of 4)
    Using the uncertainty values reported in the DEM metadata, the DEM vertical uncertainty was converted to horizontal uncertainty using the slope of the beach at 50-meter points along the MHW line, using the following steps: Slope maps were created from the DEMS within ArcMap using the 3D Analyst Raster Surface Slope tool. Next, the MHW lines were converted to 50-meter-spaced points, at which the slope value of the DEM was extracted. The average of these values for North, Central, and Southern California was used to convert the vertical uncertainty of the DEM to a horizontal uncertainty. Finally, the horizontal uncertainty and converted vertical uncertainty were summed in quadrature to calculate a final uncertainty value associated with each shoreline.
  3. What similar or related data should the user be aware of?
    Smith, Schuyler A., and Barnard, Patrick L., 2020, The impacts of the 2015/2016 El Nino on California’s sandy beaches.

    Online Links:

    Other_Citation_Details:
    Smith, S.A., and Barnard, P.L., 2020, The impacts of the 2015/2016 El Nino on California’s sandy beaches: Geomorphology

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

  1. How well have the observations been checked?
    Estimates of shoreline position accuracy using mean high water lines derived from LiDAR DEMS have been cross checked with satellite-derived shorelines, shorelines derived by the national assessment of shoreline change, and in-situ data collected by GPS surveys. However, lack of alternate data collection methods during this time limits the amount of validation possible for this dataset.
  2. How accurate are the geographic locations?
    A formal accuracy assessment of the shorelines was conducted for each region. The uncertainty associated with each LiDAR-derived shoreline is comprised of the vertical and horizontal uncertainty of the source DEM. Average beach slopes for North, Central, and Southern California were calculated and used to convert the reported vertical uncertainty of the DEM to a horizontal uncertainty. The derived horizontal uncertainty and vertical uncertainty were summed in quadrature to calculate a final uncertainty value associated with each shoreline. The horizontal accuracy (or uncertainty) for each shoreline is included within this geospatial dataset and was determined at the 95 percent confidence level.
  3. How accurate are the heights or depths?
    Although no formal vertical position accuracy assessment was conducted, the uncertainty associated with each LiDAR-derived shoreline is comprised of the vertical (and horizontal) uncertainty of the source DEM. It is assumed that uncertainty associated with the extraction of the MHW line from a DEM is negligible.
  4. Where are the gaps in the data? What is missing?
    These geospatial projections are complete. Any gaps in these data, if applicable, are a consequence of nonexisting data or existing data that did not meet quality assurance standards. Users are advised to read the rest of the metadata record and references carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    Data have undergone QA/QC and fall within expected/reasonable ranges. The MHW elevation in each analysis region (Northern, Central, and Southern California) maintained consistency with that of the National Assessment of Shoreline Change.

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:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    USA

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? These data are available in shapefile format. Each shoreline year (1998/2002, 2015, and 2016) and region (Northern, Central, and Southern California) is available as a separate shapefile. CSDGM FGDC-compliant metadata is zipped with the dataset.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 31-Dec-2020
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, California
USA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P91QSGXF/CA_1998_2016_shorelines_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:17:22 2021