Beach foreshore slope for the East Coast of the United States

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Frequently anticipated questions:

What does this data set describe?

Title: Beach foreshore slope for the East Coast of the United States
Abstract:
This data release contains foreshore slopes for primarily open-ocean sandy beaches along the East Coast of the United States (Maine through Florida). The slopes were calculated while extracting shoreline position from lidar point cloud data collected between 1997 and 2018. The shoreline positions have been previously published, but the slopes have not. An along-shore reference baseline was defined, and then 20-meter spaced cross-shore beach transects were created perpendicular to the baseline. All data points within 1 meter (along-shore) of each transect were associated with that transect. For each transect, the points on the foreshore were identified, and a linear regression was fit through the foreshore points. Beach slope was defined as the slope of the regression. The regression was evaluated at the elevation of mean high water (MHW) to yield the cross-shore location of the shoreline. In areas where more than one lidar survey is available, the slopes from each survey are provided. While most of the slopes are for sandy beaches, there are some slope data from rocky headlands and other steeper beaches. The slope data files (slopeData_EastCoast.csv and slopeData_EastCoast.shp) contain beach slope, the location at which the beach slope data was calculated (the shoreline position), and the estimated uncertainty of the shoreline position. The reference line data files (referenceLine_EastCoast.csv and referenceLine_EastCoast.shp) contain information about the reference baseline, the cross-shore transects, and the MHW values used to estimate the shoreline location. Both file types *.csv (ascii files containing comma separated values) and *.shp (binary files supported by Esri known as 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 numbers used in those publications are different that the transect numbers used here.
  1. How might this data set be cited?
    Farris, Amy S., and Weber, Kathryn M., 20240712, Beach foreshore slope for the East Coast of the United States: data release doi:10.5066/P13FC6SW, 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 East Coast of the United States: U.S. Geological Survey data release, https://doi.org/10.5066/P13FC6SW
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -81.4593
    East_Bounding_Coordinate: -69.7199
    North_Bounding_Coordinate: 43.7869
    South_Bounding_Coordinate: 25.6654
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/663d18a6d34e77890839e46f?name=browseGraphicEastCoast.jpg&allowOpen=true (JPG)
    Small section of data showing reference baseline and slope data
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 15-Sep-1997
    Ending_Date: 07-Aug-2018
    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 Vector data set. It contains the following vector data types (SDTS terminology):
      • point (333709)
    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 0.0197704219. Longitudes are given to the nearest 0.0239377492. Latitude and longitude values are specified in Decimal seconds. The horizontal datum used is North_American_Datum_1983.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    slopeData_EastCoast.shp Attribute Table
    The point shapefile file contains estimates of the foreshore beach slope at the shoreline position along the cross-shore transects. A .csv file containing the same fields (except for "FID" and "Shape") is also provided. (Source: USGS)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Shape type.
    State
    Two letter state designation (Source: USGS)
    ValueDefinition
    MEMaine
    NHNew Hampshire
    MAMassachusetts
    RIRhode Island
    NYNew York
    NJNew Jersey
    DEDelaware
    MDMaryland
    VAVirginia
    NCNorth Carolina
    SCSouth Carolina
    GAGeorgia
    FLFlorida
    Region
    Two letter region designation (Source: USGS)
    ValueDefinition
    nano region for this state
    nsNorth Shore of Massachusetts, north of Boston
    ssSouth Shore of Massachusetts, from south of Boston to Sandy Neck Inlet (Barnstable)
    icInner Cape, inner part of Cape Cod Bay Massachusetts, from Sandy Neck Inlet (Barnstable) to Provincetown
    ocOuter Cape, primarily east-facing coast of Cape Cod Massachusetts from Provincetown to Monomoy Island
    scSouth Cape, south-facing coast of Cape Cod, Massachusetts
    nkNantucket, Massachusetts, south- and east- facing coasts
    nbNantucket, Massachusetts, north- and west- facing coasts
    mvMartha's Vineyard, Massachusetts, south-facing coast
    mbMartha's Vineyard, Massachusetts, north-facing coast
    wcThe coast of Massachusetts west of Buzzards Bay. Also the western coast of Rhode Island from Narragansett to Westerly
    ecThe eastern coast of Rhode Island from Newport to the Massachusetts border.
    Year
    year of data collection, as YYYY (Source: USGS)
    Range of values
    Minimum:1997
    Maximum:2018
    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:1
    Maximum:12
    TransNum
    Transect number. Transect numbers are not unique. They restart from 0 for each state, or if the state is divided into regions, for each region. Numbers increase roughly from south to north and/or west to east. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:30057
    Units:none
    Latitude
    Latitude of calculated shoreline position. This is the location at which beach slope was estimated. (Source: USGS)
    Range of values
    Minimum:25.665433
    Maximum:43.786897
    Units:degrees
    Longitude
    Longitude of calculated shoreline position. This is the location at which beach slope was estimated. All longitude values are west. (Source: USGS)
    Range of values
    Minimum:-81.459293
    Maximum:-69.719857
    Units:degrees
    Slope
    Slope of the beach foreshore (Source: USGS)
    Range of values
    Minimum:0.289
    Maximum:33.978
    Units:degrees
    ShoreDist
    Distance between the calculated shoreline position and transect origin (at the reference baseline). Positive values denote a shoreline position seaward of the baseline, negative values denote a position landward of the baseline. (Source: USGS)
    Range of values
    Minimum:-6641.027
    Maximum:8513.614
    Units:meters
    ShoreUncy
    Estimated uncertainty of the shoreline position. (Source: USGS)
    Range of values
    Minimum:0.258
    Maximum:29.755
    Units:meters
    referenceLine_EastCoast.shp Attribute Table
    The point shapefile file includes information about the reference baseline, cross-shore transects, and mean high water (MHW) values used to calculate shorelines for the East Coast of the United States. A .csv file containing the same fields (except for "FID" and "Shape") is also included. (Source: USGS)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Shape type.
    State
    Two letter state abbreviation (Source: USGS)
    ValueDefinition
    MEMaine
    NHNew Hampshire
    MAMassachusetts
    RIRhode Island
    NYNew York
    NJNew Jersey
    DEDelaware
    MDMaryland
    VAVirginia
    NCNorth Carolina
    SCSouth Carolina
    GAGeorgia
    FLFlorida
    Region
    Two letter region designation (Source: USGS)
    ValueDefinition
    nano region for this state
    nsNorth Shore of Massachusetts, north of Boston
    ssSouth Shore of Massachusetts, from south of Boston to Sandy Neck Inlet (Barnstable)
    icInner Cape, inner part of Cape Cod Bay Massachusetts, from Sandy Neck Inlet (Barnstable) to Provincetown
    ocOuter Cape, primarily east-facing coast of Cape Cod Massachusetts from Provincetown to Monomoy Island
    scSouth Cape, south-facing coast of Cape Cod, Massachusetts
    nkNantucket, Massachusetts, south- and east-facing coasts
    nbNantucket, Massachusetts, north- and west-facing coasts
    mvMartha's Vineyard, Massachusetts, south-facing coast
    mbMartha's Vineyard, Massachusetts, north-facing coast
    wcThe coast of Massachusetts west of Buzzards Bay. Also Rhode Island from Westerly to Narragansett.
    ecThe eastern coast of Rhode Island from Newport to the Massachusetts border.
    TransNum
    Transect number. Transect numbers are not unique. They restart from 0 for each state, or if the state is divided into regions, for each region. Numbers increase roughly from south to north and/or west to east. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:30099
    Latitude
    Latitude of transect origin. (NAD83) (Source: USGS)
    Range of values
    Minimum:25.644663
    Maximum:43.783
    Longitude
    Longitude of transect origin. Negative indicates west longitude. (NAD83) (Source: USGS)
    Range of values
    Minimum:-81.45944
    Maximum:-69.698381
    X_UTM
    Easting of transect origin (UTM, NAD83, meters) (Source: USGS)
    Range of values
    Minimum:222457.60
    Maximum:777536.86
    Y_UTM
    Northing of transect origin (UTM, NAD83, meters) (Source: USGS)
    Range of values
    Minimum:2836601.83
    Maximum:4848008.59
    TransSlope
    Slope of the transect line, unitless. Defined using the formula y= m*x+b, where m is the slope, x is the easting of the transect origin, y is the northing of the transect origin and b is the y-intercept. (Source: USGS)
    Range of values
    Minimum:-211.61
    Maximum:661.87
    Y_intercept
    Y-intercept of the transect line, defined using the formula y= m*x+b, where b is the y-intercept, m is the slope, x is the easting of the transect origin, and y is the northing of the transect origin. (Source: USGS)
    Range of values
    Minimum:-266810276.46
    Maximum:92936374.94
    MHW
    The elevation of mean high water (relative to NAVD88) used to calculate the location of the shoreline. (Source: USGS)
    Range of values
    Minimum:0.0
    Maximum:1.44
    Units:meters
    UTMzone
    UTM zone in which the transect is located (Source: USGS)
    Range of values
    Minimum:17
    Maximum:19

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 S. Farris
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 (voice)
    508-457-2310 (FAX)
    afarris@usgs.gov

Why was the data set created?

Beach slope is a critical metric for coastal hazards science and is also necessary when 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 East Coast of the US.

How was the data set created?

  1. From what previous works were the data drawn?
    2000_MD_ME (source 1 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20000101, 2000 Fall East Coast NOAA/USGS/NASA Airborne LiDAR: 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), in the most recent Geoid.
    2010_RI_ME (source 2 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20200101, 2010 USACE NCMP Topobathy Lidar DEM: Northeast Atlantic Coast (CT, MA, ME, NH, RI): 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), in the most recent Geoid.
    2013-2014-MA (source 3 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20150615, 2013-2014 U.S. Geological Survey CMGP LiDAR: Post Sandy (MA, NH, RI): 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), in the most recent Geoid.
    2018_SC_MA (source 4 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20181108, 2018 USACE NCMP Topobathy Lidar: East Coast (CT, MA, ME, NC, NH, RI, SC): 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), in the most recent Geoid.
    2011_MA (source 5 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20130801, 2011 U.S. Geological Survey Topographic LiDAR: LiDAR for the North East: 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), in the most recent Geoid.
    2012_MA (source 6 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20220809, 2012 USACE Post Sandy Topographic LiDAR: Rhode Island and Massachusetts 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), in the most recent Geoid.
    2010_NY (source 7 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20231017, 2010 USACE NCMP Topobathy Lidar: New York: 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), in the most recent Geoid.
    2010_NJ (source 8 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20231030, 2010 USACE NCMP Topobathy Lidar: Atlantic Coast (NJ): 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), in the most recent Geoid.
    2010_DE (source 9 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20231017, 2010 USACE NCMP Topobathy Lidar: Atlantic Coast (DE): 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), in the most recent Geoid.
    2010_MD (source 10 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20231017, 2010 USACE NCMP Topobathy Lidar: Maryland (Post-Hurricane Earl): 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), in the most recent Geoid.
    1997_SC_DE (source 11 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20231017, 1997 Fall East Coast NOAA/USGS/NASA Airborne LiDAR: 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), in the most recent Geoid.
    2010_VA (source 12 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20231017, 2010 USACE NCMP Topobathy Lidar: Atlantic Coast (VA): 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), in the most recent Geoid.
    2017_SC_VA (source 13 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20230815, 2017 USACE NCMP Topobathy Lidar: East Coast (NY, NJ, DE, MD, VA, NC, SC, GA): 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), in the most recent Geoid.
    2010_FL_NC (source 14 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20231017, 2010 USACE NCMP Topobathy Lidar: Atlantic Coast (NC, SC, GA, FL): 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), in the most recent Geoid.
    2006_FL_GA (source 15 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20220809, 2006 US Army Corps of Engineers (USACE) East Coast Topo/Bathy Mapping Project for Florida, Georgia and South Carolina: 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), in the most recent Geoid.
    2016_FL_GA (source 16 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20330809, 2016 USACE Post-Matthew Topobathy Lidar: Southeast 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).
    2009_FL (source 17 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20231017, 2009 USACE NCMP Topobathy Lidar: Atlantic Coast, FL: 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), in the most recent Geoid.
    2017_FL (source 18 of 18)
    NOAA Office for Coastal Management (NOAA/OCM), 20220809, 2017 USACE FEMA Topobathy Lidar: Florida East 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), in the most recent Geoid.
  2. How were the data generated, processed, and modified?
    Date: 2007 (process 1 of 4)
    For each state/region, a coast-following reference baseline was digitized in UTM using Google Earth. The baselines sometimes continued across inlets, rocky headlands, or other areas where shorelines were not extracted. These baselines were loaded into Matlab (version R2007a) and equally-spaced points were defined along the lines at a 20-meter spacing. Transect lines perpendicular the baselines were calculated at each of these points. The transects are defined by their origin point (the point on the baseline), their slope, and the y-intercept using the formula: y = m*x + b, where m is the slope, b is the y intercept, x is the easting of the transect origin and y is the northing of the transect origin. This Process step was completed by Amy S. Farris. Person who carried out this activity:
    Amy S. Farris
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 (voice)
    508-457-2310 (FAX)
    afarris@usgs.gov
    Date: 2023 (process 2 of 4)
    The reference baseline and transects were merged for all states/regions. The transect origins were converted to a geographic coordinate system. However, since the transect lines are defined in UTM (NAD83) and cannot be expressed in geographic, the transect origins are also provided in UTM. The final reference line data matrix has one row for each transect and each row contains the following information: state, region, transect number, latitude and longitude of the transect origin, easting and northing of the transect origin, slope of the transect (m in the formula y=m*x+b) , y-intercept (b in the formula y=m*x+b), mean high water (MHW) elevation (meters above NAVD88), UTM zone. The height of mean high water was determined from Weber and others (2005). We do not use a continuously varying MHW, but rather use one number for a long section of coast. This value is within 15 cm of the 'true' value of MHW. The final reference line data matrix was output as both a .csv and a shapefile. All points on the baseline are given, even if no shorelines were found on the transect associated with that point. All work was done in Matlab (version R2023a) by Amy S. Farris.
    Date: 2023 (process 3 of 4)
    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 R2023a). This method utilized the transects created in the first Process Step. All lidar data points within 1 meter (in the alongshore direction) of each transect were associated with that transect. All processing was done on each 2-meter wide transect, 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. See second Process Step for information about how the height of mean high water was determined. The shoreline position on each transect has an estimated horizontal 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. This step was completed by several people: Kathryn M. Weber, Marie K. Bartlett and Amy S. Farris.
    Date: 2023 (process 4 of 4)
    The slope data for all surveys for all states were merged into a single data matrix in Matlab (version R2023a). For each survey, the following data were preserved for each transect and added as a row to the matrix of the data: state, region, year and month of survey, transect number, latitude and longitude of shoreline position, foreshore beach slope, distance from shoreline to transect origin, and shoreline uncertainty. The final slope data matrix was output as both a .csv file and a shapefile. This step was completed by Amy S. Farris.
  3. What similar or related data should the user be aware of?
    Farris, Amy S., and Weber, Kathryn M., 2024, Beach foreshore slope for the West Coast of the United States: data release 2024, U.S. Geological Survey, Reston, VA.

    Online Links:

    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, U.S. 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. East Coast. The beach slopes were calculated using many different lidar surveys conducted from 1997 to 2018. 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?
    There is no horizontal component of accuracy associated with beach slope. There is horizontal accuracy associated with each lidar dataset from which these data were estimated. This accuracy varies by data set, see the lidar survey metadata. The foreshore beach slope values are provided at our estimated 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?
    There is no vertical component of accuracy associated with beach slope. There is vertical accuracy associated with each lidar dataset from which these data were estimated. This accuracy varies by data set, see the lidar survey metadata. The reference line data file contains the values of mean high water (MHW) that were used to estimate the shoreline position. There is vertical accuracy associated with these values. These values were taken from Weber and others (2005) and do not vary continuously along the coast, but rather are constant for long stretches of coastline. The value at any particular point is estimated to be within 15 cm of the 'true' value.
  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. Most locations have more than one estimate of beach slope because multiple lidar surveys were conducted and processed. 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 did not pass our QA/QC procedures were removed. The baselines (and transects) sometimes continue across inlets, rocky headlands or other areas where shorelines were not extracted. All transects are listed, even transects for which no shoreline was found.
  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 if 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. Transect numbers are unique for each state, or if the state is divided into regions, for each region.

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_EastCoast.shp and slopeData_EastCoast.csv), the point shapefile and the tabular data for the reference line and transects (referenceLine_EastCoast.shp and referenceLine_EastCoast.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 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: 12-Jul-2024
Metadata author:
Amy S. Farris
U.S. Geological Survey
384 Woods Hole Road
Woods Hole, MA
US

508-548-8700 (voice)
508-457-2310 (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_P13FC6SW/eastCoastMetadata.faq.html>
Generated by mp version 2.9.51 on Thu Jul 18 15:07:16 2024