2012-2014 contour-derived mean high water shorelines of the Massachusetts coast used in shoreline change analysis

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What does this data set describe?

Title:
2012-2014 contour-derived mean high water shorelines of the Massachusetts coast used in shoreline change analysis
Abstract:
The Massachusetts Office of Coastal Zone Management launched the Shoreline Change Project in 1989 to identify erosion-prone areas of the coast. The shoreline position and change rate are used to inform management decisions regarding the erosion of coastal resources. In 2001, a 1994 shoreline was added to calculate both long- and short-term shoreline change rates at 40-meter intervals along ocean-facing sections of the Massachusetts coast. In 2013 two oceanfront shorelines for Massachusetts were added using 2008-2009 color aerial orthoimagery and 2007 topographic lidar datasets obtained from NOAA's Ocean Service, Coastal Services Center.
This 2018 update includes two new mean high water (MHW) shorelines for the Massachusetts coast extracted from lidar data collected between 2010-2014. The first new shoreline for the state includes data from 2010 along the North Shore and South Coast from lidar data collected by the U.S. Army Corps of Engineers (USACE) Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX). Shorelines along the South Shore and Outer Cape are from 2011 lidar data collected by the U.S. Geological Survey's (USGS) National Geospatial Program Office. Shorelines along Nantucket and Martha’s Vineyard are from a 2012 U.S. Army Corps of Engineers Post Sandy Topographic lidar survey. The second new shoreline for the North Shore, Boston, South Shore, Cape Cod Bay, Outer Cape, South Cape, Nantucket, Martha’s Vineyard, and South Coast west of Buzzards Bay is from 2013-2014 lidar data collected by the U.S. Geological Survey's (USGS) Coastal and Marine Geology Program. Shorelines were extracted from these lidar surveys using several different methods dependent on the location of the shoreline and whether or not wave data were available.
Supplemental_Information:
Cross-referenced citations are applicable to the dataset as a whole. Additional citations are located within individual process steps that pertain specifically to the method described in that step.
  1. How might this data set be cited?
    U.S. Geological Survey, 2018, 2012-2014 contour-derived mean high water shorelines of the Massachusetts coast used in shoreline change analysis: data release DOI:10.5066/P9O7S72B, 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.

    Himmelstoss, Emily A., Farris, Amy S., and Weber, Kathryn M., 2018, Massachusetts Shoreline Change Project: A GIS Compilation of Vector Shorelines for the 2018 update: data release DOI:10.5066/P9O7S72B, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Himmelstoss, E.A., Farris, A.S., and Weber, K.M., 2018, Massachusetts shoreline change project—A GIS compilation of vector shorelines for the 2018 update: U.S. Geological Survey data release, https://doi.org/10.5066/P9O7S72B.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -71.12213766
    East_Bounding_Coordinate: -69.93250218
    North_Bounding_Coordinate: 42.82296054
    South_Bounding_Coordinate: 41.24947416
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5bd86551e4b0b3fc5ce9d9b4/?name=MAcontourShoreline_2012_2014_browse.png (PNG)
    Map view of data
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 12-Nov-2012
    Ending_Date: 27-Dec-2014
    Currentness_Reference:
    ground condition of the data these shorelines are based on
  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 (1089)
    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 0.0197395052. Longitudes are given to the nearest 0.0264490611. Latitude and longitude values are specified in Decimal seconds. 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?
    MAcontourShoreline_2012_14
    contour-derived mean high water shoreline for Massachusetts coast used in shoreline change analysis. (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Coordinates defining the features.
    Contour
    The height of MHW was determined from vdatum provided by NOAA. (https://vdatum.noaa.gov/). One MHW value was used for a continuous section of coast (as opposed to using a continuously varying value). This value is always within 15 cm of the value returned by vdatum at any point along the coast. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.2
    Maximum:1.44
    Date_
    Date of shoreline position; date of survey as indicated on source material. A default date of 07/01 was assigned to shorelines where only the year was known (month and day unknown). Using July, the mid-point month of the calendar year, minimizes the potential offset to the actual shoreline date by a maximum of six months. (Source: U.S. Geological Survey) Date of the shoreline in mm/dd/yyyy
    Uncy
    Estimate of shoreline position uncertainty derived by adding in quadrature the three identified components of uncertainty described in the horizontal positional accuracy section of this metadata file. Actual shoreline position is within the range of this value (plus or minus, meters). (Source: U.S. Geological Survey)
    Range of values
    Minimum:1.4
    Maximum:3.42
    Source
    Agency that provided shoreline feature or the data source used to digitize shoreline feature. (Source: U.S. Geological Survey) Character string of length 25
    Source_b
    Method of deriving shoreline feature. These shorelines were all extracted via the same contour method, but when combined with other data for shoreline analysis this field preserves the method used to derive the shoreline. (Source: U.S. Geological Survey)
    ValueDefinition
    contourThe mean high water shoreline was extracted from lidar data using the contour method.
    ATTRIBUTE
    The shoreline reference. These contour shorelines are all referenced to Mean High Water, which is datum-based. When combining these shoreline features with other data for rate calculations this field is used to differentiate between proxy and datum-based features. (Source: U.S. Geological Survey) Character string of length 25
    Default_D
    In historic shoreline data the exact month and day of a shoreline are unknown. This field is used to indicate when a default month and day are used. A zero value indicates the date is known. This field does not apply to this dataset, but is preserved for merging this shoreline feature with other historic shoreline data for change analysis. (Source: U.S. Geological Survey)
    ValueDefinition
    0False. No default month and day were used.
    Shape_Leng
    Length of shoreline in meter units (WGS84, UTM zone 19N calculated via XTools Pro (v.16.1.2431). (Source: U.S. Geological Survey, Woods Hole Science Center)
    Range of values
    Minimum:0.265448
    Maximum:11916.775315
    Region
    Subregion of Massachusetts coast where shoreline data are located. Other shoreline files extracted from different methods required that the data be split into regions and this field correlates to those extents. (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center) Character string of length 25
    Year_
    Four digit year of shoreline (Source: U.S. Geological Survey)
    Range of values
    Minimum:2012
    Maximum:2014

Who produced the data set?

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

    508-548-8700 x2262 (voice)
    508-547-2310 (FAX)
    ehimmelstoss@usgs.gov

Why was the data set created?

Shoreline positions serve as easily understood features that can be used to describe the movement of beaches through time. This particular shoreline dataset is a mean high water (MHW) datum-based shoreline extracted using a contour method. These data are used in conjunction with other shoreline files to calculate rates of shoreline change. See the first process step for essential information to understand these data and other shoreline change related data.

How was the data set created?

  1. From what previous works were the data drawn?
    2013-2014 lidar (source 1 of 2)
    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Office for Coastal Management (OCM), and Woolpert, 20150615, 2013-2014 U.S. Geological Survey CMGP Lidar: Post Sandy (MA, NH, RI): NOAA's Ocean Service, Office for Coastal Management (OCM), Charleston, SC.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The bare earth point cloud data in LAS format (lidar data exchange file format) was used. Using the cart method to download the data, the data were downloaded in the UTM Zone 19 projection with the NAD83 horizontal datum and NAVD88 vertical datum with horizontal and vertical units in meters.
    lidar (source 2 of 2)
    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Office for Coastal Management (OCM), 20130101, 2012 USACE Post Sandy Topographic Lidar: Rhode Island and Massachusetts Coast: NOAA's Ocean Service, Office for Coastal Management (OCM), Charleston, SC.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    The bare earth point cloud data in LAS format (lidar data exchange file format) was used to extract shorelines using methods described in the process steps. Using the cart method to download the data, the data were downloaded in the UTM Zone 19 projection with the NAD83 horizontal datum and NAVD88 vertical datum with horizontal and vertical units in meters.
  2. How were the data generated, processed, and modified?
    Date: 2016 (process 1 of 6)
    Explanation of the methods used to delineate shoreline features that are a part of this update for the Massachusetts Office of Coastal Zone Management Shoreline Change Project:
    This data release has two methods of shoreline extraction: the profile method and the contour method. The profile method is further broken down into two varieties: shorelines that are extracted along open-ocean coasts and those that are sheltered.
    Profile open-ocean coast (bias): datum-based mean high water (MHW) shoreline. The elevation of MHW was obtained from Weber and others (2005). These data have an associated uncertainty table that provides the horizontal uncertainty associated with the shoreline, a proxy-datum bias value describing the unidirectional horizontal offset between the MHW shoreline and the historical proxy-based high water line (HWL) shorelines, and the uncertainty associated with the calculated proxy-datum bias value. These shorelines are polyline-M shapefiles.
    Profile not open-ocean (no bias): datum-based mean high water (MHW) shoreline. Since Weber and others (2005) only covers open-ocean coast, all MHW elevations for these data come from NOAA's vdatum (version 3.8; https://vdatum.noaa.gov/). These data have an associated uncertainty table that provides the horizontal uncertainty associated with the shoreline. These shorelines are polyline-M shapefiles.
    Contour method: this method is used along sections of the coast that were too crenulated for the for the profile method. The elevation of MHW was used from Weber and others, 2005 when available. In areas not covered by Weber and others (2005), NOAA's vdatum (version 3.8; https://vdatum.noaa.gov/) is used to determine MHW. Once this value is determined, the contour line of that value is extracted from the DEM surface in the area of interest. These shorelines are polyline shapefiles.
    Not included in this data release is another method of shoreline delineation. A brief explanation of this method is provided to convey the importance of the information contained in the uncertainty tables, even if that information is not actively used in all cases in this data release.
    Proxy-based historical shorelines: Vector shorelines digitized from georegistered T-sheets using standard editing tools in ArcMap provide a proxy-based high water line (HWL) feature that is not tidally-referenced. Individually these shorelines are stored as polyline shapefiles. In previous analyses (see Himmelstoss and others, 2011 listed in cross references) these data were published as a merged file with profile method data extracted from lidar. Therefore the published data are all polyline-M, but the historic HWL shorelines contain no linear referencing. Visually identified HWL-type proxy shorelines are virtually never coincident with datum-based MHW-type shorelines. In fact, HWL shorelines are almost universally estimated to be higher (landward) on the beach profile than MHW shorelines. Not accounting for this offset will cause shoreline change rates to be biased toward slower shoreline retreat, progradation rather than retreat, or faster progradation than in reality (for the typical case where datum-based MHW shorelines are more recent data than the proxy-based HWL shoreline dates).
    The Digital Shoreline Analysis System software used to compute rates detects when proxy-based and datum-based shorelines are present and uses linear referencing to retrieve the information on bias and uncertainty stored in the DBF table associated with the profile method shorelines and correct for the proxy-datum bias offset.
    Date: 2016 (process 2 of 6)
    In areas where the sandy coastline was complex and/or curvilinear, our preferred profile method of extracting a lidar shoreline was not an optimal choice as it is best suited for long, linear sections of coast. Instead, a contour method was used to extract the operational mean high water (MHW) shoreline.
    The height of MHW was determined from vdatum provided by NOAA. (https://vdatum.noaa.gov/). We continued the practice set out by Weber and others (2005) of using one MHW value for a continuous section of coast (as opposed to using a continuously varying value). We chose this value such that it is always within 15 cm of the value returned by vdatum at any point along the coast. For example, MHW = 0.6 m was used for all of Buzzards Bay even though vdatum shows it varying slightly over the basin. This is the contour value used to delineate the shoreline and is recorded as the contour attribute in this shapefile.
    Two data sets were used to extract MHW shorelines using the contour method. The dataset from which the majority of contour shorelines were extracted was the 2013-2014 U.S. Geological Survey Coastal and Marine Geology Program lidar data set. There were some gaps in these data along the coasts of Martha’s Vineyard and Tuckernuck Island so a second data set, the 2012 U.S. Army Corps of Engineers Post-Sandy Lidar data, was used to fill in the gaps. The lidar data were downloaded in LAS format (lidar data exchange file format) from NOAA’s Data Access Viewer: https://coast.noaa.gov/dataviewer/#/ in the UTM Zone 19 projection with the NAD83 horizontal datum and NAVD88 vertical datum.
    This process step and all subsequent process steps were performed by Amy Farris. Person who carried out this activity:
    Amy S. Farris
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2344 (voice)
    afarris@usgs.gov
    Date: 2016 (process 3 of 6)
    A series of ArcGIS tools (ArcGIS version 10.4.1) were used to extract a MHW contour from the lidar data. First, the LAS files were loaded into ArcMap using the ArcToolbox tool LAS to Multipoint, and feature classes were created using the tool Multipart to Singlepart. Location and elevation data were then added to each point in the attribute table using Add XY Coordinates. There was often overlap between the search boxes when downloading the data from the NOAA website and this resulted in repeated points in the singlepart features. These duplicate points were deleted using the Delete Identical tool in ArcToolbox. The feature classes were then divided into two subsets using the Subset Features tool. This ArcToolbox function divided the data into a training set that randomly included 90% of the points and a test set that included 10% of the points. The 10% test set was used to estimate the uncertainty associated with the gridding process. This uncertainty was found to be significantly less than the other sources of uncertainty discussed in the horizontal accuracy report section of this metadata file. The 10% omitted from the surface construction were initially going to be used to estimate a surface error for the DEM, but later in the process of extracting these shoreline features, it was decided to implement the total positional uncertainty described in the horizontal accuracy report section of this metadata file instead. The files with 90% of the points were brought into feature datasets to create terrain surfaces. The tool Terrain to Raster was then used to build 1 m x 1 m digital elevation models (DEMs) using a Natural Neighbours interpolation method.
    Date: 2016 (process 4 of 6)
    To extract the MHW shoreline from each DEM surface, the operational MHW elevation was entered into the ArcGIS tool Contour as the contour value, and the Smooth Line tool was used to smooth the resulting contour with a 10 m smoothing tolerance and the PAEK smoothing algorithm. The shoreline was then manually edited with the lidar data displayed with categorized elevation values to highlight the MHW values. Segments of the contour that did not fall near MHW were removed. Sometimes the lidar data did not extend down to MHW, resulting in gaps in the contour.
    Date: 2016 (process 5 of 6)
    The feature class was exported out of the geodatabase to shapefile format by right-clicking on the feature class name in the table of contents of the ArcMap project and choosing Export > Shapefile.
    Date: 2016 (process 6 of 6)
    The data were projected in Esri's ArcToolbox v10.5 > Data Management Tools > Projections and Transformations > Feature > Project. Parameters: input projection = UTM zone 19N (NAD83); output projection = geographic coordinates (WGS84); transformation = WGS_1984_To_NAD_1983_1.
  3. What similar or related data should the user be aware of?
    Thieler, E.R., Smith, T.L., Knisel, Julia, and Sampson, D.W., 2013, Massachusetts Shoreline Change Mapping and Analysis Project, 2012 Update: Open-File Report 2012-1189, U.S. Geological Survey, Reston, VA.

    Online Links:

    Smith, Theresa L., Himmelstoss, Emily A., and Thieler, E. Robert, 2013, 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:

    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, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Himmelstoss, Emily A., Kratzmann, Meredith G., Hapke, Cheryl J., Thieler, E. Robert, and List, Jeffrey, 20110119, The National Assessment of Shoreline Change: A GIS Compilation of Vector Shorelines and Associated Shoreline Change Data for the New England and Mid-Atlantic Coasts: Open-File Report 2010-1119, 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:

    Himmelstoss, Emily A., Farris, Amy S., Henderson, Rachel E., Kratzmann, Meredith G., Ergul, Ayhan, Zhang, Ouya, and Zichichi, Jessica L., 2018, Digital Shoreline Analysis System (version 5.0)): U.S. Geological Survey software: software release version 5.0, 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 attributes are based on the requirements of the Digital Shoreline Analysis System (DSAS) software, please refer to cross reference for citation.
  2. How accurate are the geographic locations?
    We accounted for 3 sources of uncertainty in the contour method:
    1) The vertical uncertainty of the lidar data, which is stated as 0.1 m RMS in the lidar metadata;
    2) a mean high water (MHW) uncertainty of 0.15 m to account for our simplified use of a single MHW value for a section of coast when in reality MHW continuously varies; and
    3) the horizontal uncertainty due to the 1 meter cell size of the DEM.
    This 1 meter cell limits us to a plus or minus 0.5 m confidence in the location of the shoreline. Since the first two sources of uncertainty are vertical measurements, we converted both of them to a horizontal uncertainty using the beach slope. The beach slope was found by extracting the slope of the DEM along the contour shoreline ( ArcToolbox >> 3D Analyst >> Raster Surface >> Slope). We divided both of the vertical uncertainty terms by the tangent of the beach slope in order to get the horizontal component of the two vertical uncertainty terms. In order to estimate the total horizontal uncertainty for each subregion, the three, now horizontal, components of uncertainty were averaged over the subregion and then added in quadrature. These are stored in the attribute table. The average uncertainty for the contour shoreline for the state is 2.04 meters.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Although not a continuous shoreline for the state of Massachusetts, this shoreline file is complete and contains all shoreline segments where shoreline position data needed to be extracted using this method. Remaining gaps in these data are where shorelines were derived by a different method or are a consequence of non-existing data or existing data that did not meet quality assurance standards.
  5. How consistent are the relationships among the observations, including topology?
    Adjacent shoreline segments do not overlap and are not necessarily continuous. Shorelines were displayed on top of Esri World Imagery in map view to verify that no erroneous data were included. There were some gaps in the 2013-2014 data along the coasts of Martha’s Vineyard and Tuckernuck Island so 2012 data were used to fill in the gaps.

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
    Federal Center, Building 810, MS 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? The dataset contains the polyline shapefile of shoreline data derived from a contour method, (MAcontour_pShoreline_2012_14.shp and other shapefile components), browse graphic (MAcontourShoreline_2012_14_browse), and the FGDC CSDGM metadata in XML and TEXT format
  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.
    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?
  5. What hardware or software do I need in order to use the data set?
    These data are available in a polyline shapefile format. The user must have software to read and process the data components of a shapefile.

Who wrote the metadata?

Dates:
Last modified: 30-Oct-2018
Metadata author:
Emily A. Himmelstoss
U.S. Geological Survey
384 Woods Hole Road
Woods Hole, MA
USA

508-548-8700 (voice)
508-548-8700 x2262 (FAX)
ehimmelstoss@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/data_release/DR_P9O7S72B/MAcontourShoreline_2012_2014.shp.faq.html>
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