2013-14 Massachusetts Lidar-Derived Dune Toe Point Data

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Frequently anticipated questions:


What does this data set describe?

Title: 2013-14 Massachusetts Lidar-Derived Dune Toe Point Data
Abstract:
This data release of dune metrics for the Massachusetts coast is part of a 2018 update to the Massachusetts Shoreline Change Project. Because of continued coastal population growth and the increased threat of coastal erosion, the Massachusetts Office of Coastal Zone Management (CZM) launched the Shoreline Change Project in 1989 to identify erosion-prone areas of the coast. Maps of historic shoreline locations from the mid-1800s to 1978 were produced from multiple data sources, and in 2001, a 1994 shoreline was added to enable the calculation of long- and short-term shoreline change rates. In 2013, the U.S. Geological Survey (USGS), in cooperation with CZM, delineated an additional oceanfront shoreline using 2007 topographic lidar data and 2008–9 color aerial orthoimagery.
Further cooperation between CZM and the USGS resulted in this 2018 update, intended to increase the understanding of coastal erosion and to support coastal management decision making. This update includes beach shorelines, marsh shorelines, and dune metrics, all of which were derived from topographic lidar data. This data release, which is part of the 2018 update, defines the position and elevation of the most seaward dune crest and toe along the Massachusetts coast as derived from 2013–14 lidar data. In the absence of a dune, the peak of the berm or the seaward edge of a bluff, headland, or hard structure (for example, a seawall, road, or parking lot) was chosen as a proxy for the dune crest. Where possible, the dune toe was placed at the base of the proxy feature.
Supplemental_Information:
The crest of the most seaward sand dune is often the first line of defense for coastal areas during storms. Determining the probability of collision, overwash, or inundation during a storm is just as vital in regions where no dunes are present. Therefore, in the absence of a dune, the peak of the feature that would serve as the first line of defense was chosen as a proxy for the dune crest. This includes the seaward-most edge of a headland, bluff or other hard structure (e.g., seawall, road, parking lot), or the peak of the berm. Where possible, the dune toe was placed at the base of these proxy features. Accompanying dune crest position and elevation data are available from the larger work citation.
  1. How might this data set be cited?
    Weber, Kathryn M., 2018, 2013-14 Massachusetts Lidar-Derived Dune Toe Point Data: data release DOI:10.5066/P970QVB1, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Weber, Kathryn M., 2018, Dune Metrics for the Massachusetts Coast as Derived From 2013-14 Topographic Lidar Data: data release DOI:10.5066/P970QVB1, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Weber, K.M., 2018, Dune metrics for the Massachusetts coast as derived from 2013-14 topographic lidar data: U.S. Geological Survey data release, https://doi.org/10.5066/P970QVB1.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -71.1135
    East_Bounding_Coordinate: -69.9292
    North_Bounding_Coordinate: 42.8746
    South_Bounding_Coordinate: 41.2393
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5bca0f11e4b0fc368ebff85a?name=MA_2013_2014_DuneMetrics_BrowseGraphic.png (PNG)
    Image showing dune crest and toe points atop aerial photography near Chatham, MA, and figure showing the location of the dune crest and toe on a cross-shore beach profile.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 16-Nov-2013
    Ending_Date: 27-Dec-2014
    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):
      • Entity point (24355)
    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 0.0197394137. Longitudes are given to the nearest 0.0264575256. 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?
    MA_2013_2014_DuneToe.shp Attribute Table
    Massachusetts dune toe position and elevation. (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.
    Region
    Region of Massachusetts. (Source: USGS)
    ValueDefinition
    Cape Cod BayInner Cape region along Cape Cod Bay from Long Point to Yarmouth.
    Martha's Vineyard SoundsideCoastline of Martha's Vineyard facing Vineyard Sound.
    Martha's VineyardMartha's Vineyard's southwestern, southern, and eastern coastlines.
    Nantucket SoundsideCoastlines of Muskeget, Tuckernuck, and Nantucket Islands facing Nantucket Sound.
    NantucketCoastlines of Muskeget, Tuckernuck, and Nantucket Islands facing the Atlantic Ocean.
    North ShoreNorth Shore region of Massachusetts from the New Hampshire border to Revere, MA.
    Outer CapeOuter Cape Cod from Long Point to Monomoy Island.
    South CapeSouthern region of Cape Cod from Woods Hole to West Chatham.
    South ShoreSouth Shore region of Massachusetts from Hull to Barnstable.
    South CoastMassachusetts coast along part of Buzzards Bay from the Rhode Island border to New Bedford, MA.
    Segment
    Segment ID number. Each region has its own coast-following reference line along which data are processed. Each reference line is divided into segments and each segment begins at profile number 1. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:178
    Profile
    Grid row number corresponding to a cross-shore beach profile location. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:1699
    Longitude
    Dune crest location expressed in degrees of longitude (WGS84). (Source: USGS)
    Range of values
    Minimum:-71.1135014681
    Maximum:-69.9292304355
    Units:decimal degrees
    Latitude
    Dune crest location expressed in degrees of latitude (WGS84). (Source: USGS)
    Range of values
    Minimum:41.239341664
    Maximum:42.8746149095
    Units:decimal degrees
    Easting
    UTM easting location of dune crest (NAD83, Zone 19). (Source: USGS)
    Range of values
    Minimum:323598.031808
    Maximum:422715.691538
    Units:meters
    Northing
    UTM northing location of dune crest (NAD83, Zone 19). (Source: USGS)
    Range of values
    Minimum:4565823.2089
    Maximum:4748491.07285
    Units:meters
    Elevation
    Dune toe elevation relative to NAVD88. (Source: USGS)
    Range of values
    Minimum:0.488247
    Maximum:10.573711
    Units:meters
    Error
    Root mean squared vertical error of dune toe. (Source: USGS)
    Range of values
    Minimum:0.0165904
    Maximum:3.289215
    Units:meters
    Entity_and_Attribute_Overview:
    These data are also available in CSV format. The CSV file contains the same attributes (without the FID and Shape attributes) as the shapefile, with the same values and definitions. The first row of the CSV file is the header line containing the attribute name.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

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

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

Why was the data set created?

This dataset provides the elevation and position of the toe of the most seaward dune along the Massachusetts coast. Dune crest and toe elevation data are essential parameters for determining the vulnerability of coastal areas from storms. Dune crest elevation is used as a threshold for determining the probability of overwash and inundation due to waves and storm surge. Dune toe elevation is used to determine the probability of collision (erosion of the base of the dune), and dune toe location allows for the calculation of both beach width and beach slope.

How was the data set created?

  1. From what previous works were the data drawn?
    2013-14 Lidar data (source 1 of 1)
    Department of Commerce, National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), United States Geological Survey (USGS), Coastal and Marine Geology Program (CMGP), and Woolpert, 20150615, 2013-2014 U.S. Geological Survey CMGP LiDAR: Post Sandy (MA, NH, RI).

    Online Links:

    Type_of_Source_Media: Digital and/or Hardcopy
    Source_Contribution:
    The topographic lidar data were used to identify dune toe position and elevation.
  2. How were the data generated, processed, and modified?
    Date: 2018 (process 1 of 1)
    2013–14 lidar elevation data were downloaded from NOAA’s online data access viewer (https://coast.noaa.gov/dataviewer/#/) in LAS format (NAD83 2011, UTM Zone 19N (meters) and NAVD88 (meters)) for ten regions along the Massachusetts coast. These regions include: the North Shore, South Shore, Cape Cod Bay, Outer Cape, South Cape, part of the South Coast along Buzzard’s Bay, the southwestern, southern, and eastern coastlines of Martha’s Vineyard, the Vineyard Sound-facing coastline of Martha’s Vineyard, the Atlantic Ocean-facing coastlines of Muskeget, Tuckernuck, and Nantucket Islands, and the Nantucket Sound-facing coastlines of Muskeget, Tuckernuck, and Nantucket Islands. Each of the ten regions has its own coast-following reference line along which the lidar data are processed, and each reference line is divided into segments.
    The lidar point data were processed segment by segment along each region’s reference line to extract the seaward-most dune toe following methods developed by Stockdon and others, 2012. The elevation data for each segment were interpolated in MATLAB 2017a to create a shore-parallel grid with a resolution of 10 m in the longshore direction and 2.5 m in the cross-shore. Each 10 m wide grid row is a cross-shore profile along which dune features are extracted. Each segment grid begins at profile number one, and for each profile, the MATLAB algorithm identifies the dune toe as the location of maximum slope change between the shoreline and the dune crest. The vertical error, which is based on the scatter of the data, is also calculated for each point. See Stockdon and others, 2012 for details.
    The MATLAB algorithm was run for all segments in each region. Within the program, the geographic coordinates (WGS84) were calculated for each point and the automatically-extracted dune toe data, which includes dune toe elevation, error, and location in both eastings/northings and latitude/longitude, were written to ArcGIS shapefiles using MATLAB’s shapewrite.m script and Keyhole Markup Language (kml) files.
    The dune toe locations were manually examined to ensure that an appropriate alongshore feature was identified. This was done by simultaneously viewing the data in three ways: dune toe kml files were viewed on 2014 Google Earth imagery, the shapefiles were viewed on DigitalGlobe world imagery in ArcMap, and the dune crest, toe, and lidar data (interpolated and point data) were viewed for each grid profile in a MATLAB Graphical User Interface (GUI). The GUI allowed for the deleting or moving of points as necessary to produce a final shapefile of dune toe points for each region. In the absence of a dune, the beach berm or seaward edge of the headland, cliff, bluff or hard structure (e.g., road, parking lot, seawall) was extracted since those features would serve as the first line of defense during a storm. Where appropriate, the dune toe was placed at the base of these proxy features. Much manual editing and deleting was required in developed regions as well as in regions with complex topography. The dune toe shapefiles for each of the ten regions were combined in ArcMap (ArcToolbox >> Data Management Tools >> General >> Merge) to create a final shapefile of dune toe position and elevation for the entire state.
    A coordinate system transformation of the dune crest data was required for the points to correspond with the beach and marsh shoreline data that are part of this update to the Shoreline Change Project. Using ArcGIS version 10.5, the dune crest shapefile was transformed from the UTM zone 19 (NAD83 2011) coordinate system to the WGS84 geographic coordinate system (ArcToolbox >> Data Management Tools >> Projections and Transformations >> Project) using the “NAD_1983_HARN_To_NAD_1983_2011 + NAD_1983_HARN_To_WGS_1984” transformation. The DBF file of the shapefile was then saved as a CSV file using Microsoft Excel (version 2016). Person who carried out this activity:
    Kathryn M. Weber
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)
    kweber@usgs.gov
    Data sources used in this process:
    • 2013-14 Lidar data
  3. What similar or related data should the user be aware of?
    Massachusetts Office of Coastal Zone Management, 2018, Massachusetts Shoreline Change Project.

    Online Links:

    Thieler, E. Robert, O'Connell, James F., and Schupp, Courtney A., 2001, The Massachusetts Shoreline Change Project: 1800s to 1994 Technical Report: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Thieler, E. Robert, Smith, Theresa L., Knisel, Julia M., and Sampson, Daniel W., 2013, Massachusetts Shoreline Change Mapping and Analysis Project, 2013 Update: Open-File Report 2012-1189, U.S. Geological Survey, Reston, VA.

    Online Links:

    Smith, Theresa L., Himmelstoss, Emily A., and Thieler, E. Robert, 2012, Massachusetts Shoreline Change Project: A GIS Compilation of Vector Shorelines and Associated Shoreline Change Data for the 2013 Update: Open-File Report 2012-1183, U.S. Geological Survey, Reston, VA.

    Online Links:

    Stockdon, Hilary F., Doran, Kara J., Thompson, David M., Sopkin, Kristin L., Plant, Nathaniel G., and Sallenger, Asbury H., 2012, National Assessment of Hurricane-Induced Coastal Erosion Hazards: Gulf of Mexico: Open-File Report 2012-1084, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    The general methodology detailed in this report was used to extract the location and elevation of the dune toe points.

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?
    Horizontal accuracy of the dune toe and dune crest positions is estimated to be 0.42 m which is the horizontal accuracy of the lidar data at the 95 percent confidence level.
  3. How accurate are the heights or depths?
    The calculated vertical error for each dune crest and toe point was based solely on the scatter of the lidar data in the grid cells. However, vertical accuracy is also partially dependent on the positional accuracy of the lidar data itself which is 0.189 m at the 95th percentile level for this data set.
  4. Where are the gaps in the data? What is missing?
    This dune toe data set is complete for all regions in Massachusetts where this method could be used (i.e., regions where a shore-parallel reference line was available). These data adequately represent the dune toe at the time of the survey. Remaining gaps in the dune data are a consequence of gaps in the lidar data, an unresolvable dune feature due to vegetation or structures that resulted in too much noise, features with indistinct edges (e.g., headlands or bluffs), dune toes obscured by water, bermed beaches with no dune toes, or points that did not meet quality assurance standards.
  5. How consistent are the relationships among the observations, including topology?
    The dune features were QA/QC’d on aerial imagery in both ArcMap and Google Earth, on the gridded elevation surfaces in ArcMap, and on the grid profiles in MATLAB to ensure that appropriate features were chosen. Points were adjusted or deleted as necessary. In the absence of a dune, the seaward edge of the headland, bluff or hard structure (e.g., seawall, road, parking lot), or the peak of the berm was chosen as the dune crest. If the dune crest was located at the edge of a hard structure or bluff, the dune toe was placed at the base of that feature. It is possible to have a dune crest but no corresponding dune toe for any profile if the dune toe was not discernable by the automatic algorithm or if it did not meet quality assurance standards.

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. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations.
  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 file MA_2013_2014_DuneToe.zip contains the shapefile MA_2013_2014_DuneToe.shp and its components, the CSV file MA_2013_2014_DuneToe.csv, FGDC CSDGM metadata (HTML, XML, and TXT formats), and the browse graphic MA_2013_2014_DuneMetrics_BrowseGraphic.png.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, 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 information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.
    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, product, or firm 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: 06-Nov-2018
Metadata author:
U.S. Geological Survey
Attn: Kathryn M. Weber
Oceanographer
384 Woods Hole Road
Woods Hole, MA
USA

(508) 548-8700 (voice)
(508) 457-2310 (FAX)
kweber@usgs.gov
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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