Beach foreshore slope for the West Coast of the United States

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Frequently anticipated questions:

What does this data set describe?

Title: Beach foreshore slope for the West Coast of the United States
Abstract:
This data release contains foreshore slopes for primarily open-ocean sandy beaches along the west coast of the United States (California, Oregon and Washington). The slopes were calculated while extracting shoreline position from lidar point cloud data collected between 2002 and 2011. The shoreline positions have been previously published, but the slopes have not. A reference baseline was defined and then evenly-spaced cross-shore beach transects were created. Then all data points within 1 meter of each transect were associated with each transect. Next, it was determined which points were one the foreshore, and then a linear regression was fit through the foreshore points. Beach slope was defined as the slope of the regression. Finally, the regression was evaluated at the elevation of Mean High Water (MHW) to yield the location of the shoreline. In some areas there was more than one lidar survey available; in these areas the slopes from each survey are provided. While most of the slopes are for sandy beaches, there is some slope data from rocky headlands and other steeper beaches. These data files (slopeData_WestCoast.csv and slopeData_WestCoast.shp) contain beach slope, the location the beach slope data was calculated (the shoreline position), and the estimated uncertainty of the shoreline position. The accompanying data files (referenceLine_WestCoast.csv and referenceLine_WestCoast.shp) contain information about the reference baseline, the cross shore transects, and the MHW values used to estimate the shoreline location. The csv and shapefiles contain the same information, both file types are provided as a convenience to the user.
Supplemental_Information:
The shorelines that were derived when these slopes were calculated can be accessed through the USGS National Shoreline Change Data Catalog: https://www.sciencebase.gov/catalog/item/5b97f1b4e4b0702d0e842183 Note that the transect number used in these publications are different that the transect numbers used here.
  1. How might this data set be cited?
    Farris, Amy S., and Weber, Kathryn M., 20240410, Beach foreshore slope for the West Coast of the United States: data release doi:10.5066/P137S83C, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Farris, Amy S., and Weber, Kathryn M., 2024, Beach foreshore slope for the West Coast of the United States: data release doi:10.5066/P137S83C, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Other_Citation_Details:
    Suggested citation:Farris, A.S., and Weber, K.M., 2024, Beach Foreshore slope for the West Coast of the United States: U.S. Geological Survey data release, https://doi.org/10.5066/P137S83C
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -124.7400
    East_Bounding_Coordinate: -117.1200
    North_Bounding_Coordinate: 48.3500
    South_Bounding_Coordinate: 32.5300
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/65a0296bd34e5af967a3841d?name=slope_BrowseGraphic.png (PNG)
    Small section of data showing refrence baseline and slope data
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 01-Sep-2002
    Ending_Date: 30-Jul-2011
    Currentness_Reference:
    ground condition
  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 Point data set. It contains the following vector data types (SDTS terminology):
      • Point
    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 0.0197394080. Longitudes are given to the nearest 0.0264580536. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is WGS_1984.
      The ellipsoid used is WGS_84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    slopeData_WestCoast.csv and slopeData_WestCoast.shp
    The point shapefile file includes foreshore beach slopes for the sandy beaches of California, Oregon and Washington. A .csv file containing the same fields (except for "FID" and "Shape") is also included. Point object count: 98,232. (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.
    State
    Two letter state designation (Source: USGS)
    ValueDefinition
    CACalifornia
    OROregon
    WAWashington
    Region
    Two letter region designation. Oregon and Washington don't have regions. (Source: USGS)
    ValueDefinition
    soSouthern California
    ceCentral California
    noNorthern California
    nano regions for this state
    Year
    Year of data collection, as YYYY (Source: USGS)
    Range of values
    Minimum:2002
    Maximum:2011
    Units:years
    Month
    Approximate month of data collection; as MM. Occasionally, some lidar surveys extended over multiple months. In these cases the month with the most data was listed. (Source: USGS)
    Range of values
    Minimum:5
    Maximum:10
    Units:number of month
    TransNum
    Transect number. Transect numbers are unique for each state, or if the state is divided into regions, for each region. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:79665
    Latitude
    Latitude of calculated shoreline position. This is the location at which beach slope was estimated. WGS84 (Source: USGS)
    Range of values
    Minimum:32.5345696845241
    Maximum:48.3425714475071
    Units:decimal degrees
    Longitude
    Longitude of calculated shoreline position. This is the location at which beach slope was estimated. Negative indicates west longitude. WGS84 (Source: USGS)
    Range of values
    Minimum:-124.731893662584
    Maximum:-117.124253831717
    Units:decimal degrees
    Slope
    Slope of the beach foreshore (Source: USGS)
    Range of values
    Minimum:0.247
    Maximum:33.809
    Units:degrees
    ShoreDist
    Distance between the calculated shoreline position and transect origin (at the reference baseline). Positive values are seaward of the baseline, negative values are landward of the baseline. (Source: USGS)
    Range of values
    Minimum:-1437.0327
    Maximum:715.671
    Units:meters
    ShoreUncy
    Estimated uncertainty of the shoreline position. (Source: USGS)
    Range of values
    Minimum:0.279
    Maximum:41.520
    Units:meters
    Entity_and_Attribute_Overview:
    This section describes the tabular data associated with the shapefile and the corresponding csv file “slopeData_WestCoast (.shp/.csv)”. The tabular .csv data does not have the attributes "FID" or "Shape". The shapefile is projected in GCS_WGS_1984.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey - ScienceBase

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Amy S. Farris
    • Kathryn M. Weber
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Amy Farris
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole Road, MA
    USA

    508-548-8700 x2344 (voice)
    508-547-2310 (FAX)
    afarris@usgs.gov

Why was the data set created?

Beach slope is a critical metric for coastal hazards science and is also necessary for extracting shorelines from satellite imagery. Shorelines derived from satellite data must be tidally-corrected to a reference elevation using the slope of the beach. The beach slope data presented here will be beneficial for advancing our understanding of coastal processes and for quantifying and predicting shoreline change and storm impacts along the Pacific coast.

How was the data set created?

  1. From what previous works were the data drawn?
    2009 California (source 1 of 6)
    NOAA Office for Coastal Management (NOAA/OCM), 20150313, 2009 USACE NCMP Topobathy Lidar: California: NOAA Office for Coastal Management (NOAA/OCM), Charleston, SC.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The bare-earth lidar point cloud data in LAS format were used to calculate beach slope using methods described in the process steps. The point data were downloaded using the cart feature in the appropriate UTM Zone projection with NAD83 horizontal datum and NAVD88 vertical datum (meters).
    2010 California (source 2 of 6)
    NOAA Office for Coastal Management (NOAA/OCM), 20150313, 2010 USACE NCMP Topobathy Lidar: California: NOAA Office for Coastal Management (NOAA/OCM), Charleston, SC.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The bare-earth lidar point cloud data in LAS format were used to calculate beach slope using methods described in the process steps. The point data were downloaded using the cart feature in the appropriate UTM Zone projection with NAD83 horizontal datum and NAVD88 vertical datum (meters).
    2011 California (source 3 of 6)
    NOAA Office for Coastal Management (NOAA/OCM), 20150414, 2011 USACE NCMP Topobathy Lidar: California: NOAA Office for Coastal Management (NOAA/OCM), Charleston, SC.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The bare-earth lidar point cloud data in LAS format were used to calculate beach slope using methods described in the process steps. The point data were downloaded using the cart feature in the appropriate UTM Zone projection with NAD83 horizontal datum and NAVD88 vertical datum (meters).
    2010 OR and WA (source 4 of 6)
    NOAA Office for Coastal Management (NOAA/OCM), 20100101, 2010 USACE NCMP Topobathy Lidar: Oregon and Washington: NOAA Office for Coastal Management (NOAA/OCM), Charleston, SC.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The bare-earth lidar point cloud data in LAS format were used to calculate beach slope using methods described in the process steps. The point data were downloaded using the cart feature in the appropriate UTM Zone projection with NAD83 horizontal datum and NAVD88 vertical datum (meters).
    2009 OR (source 5 of 6)
    NOAA Office for Coastal Management (NOAA/OCM), 20110401, 2009 Oregon Department of Geology and Mineral Industries (DOGAMI) Oregon Lidar: North Coast: NOAA Office for Coastal Management (NOAA/OCM), Charleston, SC.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The bare-earth lidar point cloud data in LAS format were used to calculate beach slope using methods described in the process steps. The point data were downloaded using the cart feature in the appropriate UTM Zone projection with NAD83 horizontal datum and NAVD88 vertical datum (meters).
    2002 OR and WA (source 6 of 6)
    NOAA Office for Coastal Management (NOAA/OCM), 20160523, 2002 NASA/USGS Airborne LiDAR Assessment of Coastal Erosion (ALACE) Project for California, Oregon, and Washington Coastlines: NOAA Office for Coastal Management (NOAA/OCM), Charleston, SC.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The bare-earth lidar point cloud data in LAS format were used to calculate beach slope using methods described in the process steps. The point data were downloaded using the cart feature in the appropriate UTM Zone projection with NAD83 horizontal datum and NAVD88 vertical datum (meters).
  2. How were the data generated, processed, and modified?
    Date: 25-Jan-2019 (process 1 of 2)
    A transect-based method described in Farris and others (2018) was used to estimate the slope of the foreshore of the beach using Matlab (version 2019b). This method utilized 20 meter spaced transects oriented perpendicular to a coast-following reference line. All lidar data points within 1 meter of each transect were associated with that transect. All processing was done on the 2 meter wide transects, working on a single transect at a time. For each transect, points on the foreshore were identified and a linear regression was fit through them. Foreshore beach slope was defined as the slope of the regression line. The regression was evaluated at the elevation of Mean High Water (MHW) to yield the location of the shoreline.
    The height of Mean High Water was determined from Weber and others (2005).
    The shoreline position on each transect has an estimated uncertainty associated with it. This uncertainty includes four components: 1) the 95% confidence interval on the linear regression estimate of the shoreline position; 2) the vertical error of the raw lidar data as reported in the lidar data’s metadata; 3) a 15 cm vertical error in our chosen value of MHW, and; 4) the uncertainty due to extrapolation (if the shoreline was determined using extrapolation). These four components of uncertainty were added in quadrature to yield a total error for each shoreline point.
    The accompanying data files (referenceLine_WestCoast.csv and referenceLine_WestCoast.shp) contain information about the reference baseline, transects and the MHW values used to estimate the shoreline location. This step was completed by several people: Dave Reid, Kathryn M. Weber and Amy S. Farris.
    Farris, A.S., Weber, K.M., Doran, K.S., and List, J.H., 2018, Comparing methods used by the U.S. Geological Survey Coastal and Marine Geology Program for deriving shoreline position from lidar data: U.S. Geological Survey Open-File Report 2018–1121, 13 p., https://doi.org/10.3133/ofr20181121 Person who carried out this activity:
    Amy S. Farris
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2344 (voice)
    508-457-2310 (FAX)
    afarris@usgs.gov
    Data sources used in this process:
    • 2009 California
    • 2010 California
    • 2011 California
    • 2010 OR and WA
    • 2009 OR
    • 2002 OR and WA
    Date: 05-Jun-2023 (process 2 of 2)
    The slope data for all surveys for all states were merged into a single data matrix in Matlab (ver 2023a). For each transect in each survey the following data were preserved and added as a row to the matrix of all of the data: transect number, state, region, year and month of survey, latitude and longitude of shoreline position, beach slope, distance from shoreline to transect origin, and shoreline uncertainty. A csv file of this matrix was written. A shapefile was also created. This step was completed by Amy S. Farris.
  3. What similar or related data should the user be aware of?
    Farris, Amy S., Weber, Kathryn M., Doran, Kara S., and List, Jeffrey H., 2018, Comparing methods used by the U.S. Geological Survey Coastal and Marine Geology Program for deriving shoreline position from lidar data: Open-File Report 2018-1121, US Geological Survey, Reston, VA.

    Online Links:

    Weber, Kathryn M., List, Jeffrey H., and Morgan, Karen L.M., 2005, An operational mean high water datum for determination of shoreline position from topographic lidar data: Open-File Report 2005-1027, U.S. Geological Survey, Reston, VA.

    Online Links:

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

  1. How well have the observations been checked?
    The data provided here consist of estimates of the foreshore slopes of primarily sandy beaches along the U.S. Pacific coastline. The beach slopes were calculated using 6 different lidar surveys conducted from 2002 to 2011. The accuracy of the lidar point cloud elevation data from these surveys varies, with the oldest surveys being the least accurate. There are several factors that affect the accuracy of the beach slopes. These vary by survey and include: the accuracy of the lidar data, the scatter in the lidar data, the density of lidar data on the foreshore, the width of the foreshore, and the slope of the foreshore. In addition, this methodology assumes that the slope of the foreshore is constant along the transect from the water to the berm. While this assumption is usually valid, we do not know how valid it is at any individual transect. The best way to assess the accuracy of a given slope value is to compare it to adjacent values in both space and time.
  2. How accurate are the geographic locations?
    Since the data are beach slope, there is no horizontal component of accuracy. There is horizontal accuracy associated with each lidar dataset from which these data were estimated. This accuracy varies by data set, see lidar metadata. The foreshore beach slope values are provided at our estimate of shoreline position. Our estimated horizontal accuracy of shoreline position is provided with the data, see the attribute "ShoreUncy". See process step for details about how this value was calculated.
  3. How accurate are the heights or depths?
    Since the data are beach slope, there is no vertical component of accuracy. There is vertical accuracy associated with each lidar dataset from which these data were estimated. This accuracy varies by data set, see lidar metadata.
  4. Where are the gaps in the data? What is missing?
    Beach slopes were calculated primarily on open-ocean, sandy beaches. Some slopes on non-sandy beaches and rocky headlands are included. There are some large gaps in the slope data. These are due to gaps in the lidar data. Additional small gaps were created when data that didn’t pass our QA/QC procedures were removed.
  5. How consistent are the relationships among the observations, including topology?
    Beach slopes were automatically calculated for each transect during the shoreline extraction process. If no shoreline point was found on a transect or the shoreline point did not pass QA/QC procedures, that transect will not have a value for slope. There was more than one lidar survey available for many transects. Shorelines and slopes were calculated for each lidar survey. The beach slopes vary due to both measurement error and natural variability of the system.

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 as the originator of the dataset.
  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
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The dataset contains the point shapefile and the tabular data for the foreshore beach slope, (slopeData_WestCoast.shp and slopeData_WestCoast.csv), browse graphic (slope_BrowseGraphic.png), and the FGDC CSDGM metadata in XML format.
  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 for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
  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 a point shapefile format. The user must have software to read and process the data components of a shapefile.

Who wrote the metadata?

Dates:
Last modified: 10-Apr-2024
Metadata author:
Amy S. Farris
U.S. Geological Survey
384 Woods Hole Road
Woods Hole, MA
USA

508-548-8700 (voice)
508-548-8700 x2306 (FAX)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS.
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P137S83C/slopeData_WestCoast_Metadata.faq.html>
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