Mean High Water Shorelines for the Outer Cape of Massachusetts from Nauset Inlet to Race Point (1998-2005)

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Frequently anticipated questions:

What does this data set describe?

Title:
Mean High Water Shorelines for the Outer Cape of Massachusetts from Nauset Inlet to Race Point (1998-2005)
Abstract:
This data release contains mean high water (MHW) shorelines for the Outer Cape of Cape Cod, Massachusetts, from Nauset Inlet to Race Point. From 1998-2005, the U.S. Geological Survey surveyed 45 kilometers of coastline 111 times using a ground-based system called Surveying Wide-Area Shorelines (SWASH). The SWASH system used a six-wheeled amphibious all-terrain vehicle as a platform for an array of Global Positioning System sensors. High-accuracy measurements of horizontal position, vertical position, and beach slope were collected at 0.5-second intervals as the vehicle traversed a single, shore-parallel line along the foreshore.
The data were interpolated onto a coast-following reference line at 2-meter intervals. The shoreline position (defined as the intersection of the MHW datum with the foreshore) was determined by extrapolating from the location of the vehicle-driven track to the location of the MHW contour. The uncertainty for each shoreline point was calculated and the shoreline data were written to netCDF and ASCII csv files. This SWASH dataset represents a unique time series for quantifying large-scale coastal evolution, seasonal shoreline variability, and coastal behavior due to storms.
Supplemental_Information:
These data are related to 88 field activities. Survey dates, field activity numbers, and online linkages to the field activity pages are listed in the supplemental document: CapeCod_SWASH_FieldActivity_OnlineLinkages.pdf.
  1. How might this data set be cited?
    Farris, Amy S., Weber, Kathryn M., and List, Jeffrey H., 20200922, Mean High Water Shorelines for the Outer Cape of Massachusetts from Nauset Inlet to Race Point (1998-2005): data release DOI:10.5066/P9GWL52F, 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., Weber, K.M., and List, J.H., 2020, Mean high water shorelines for the Outer Cape of Massachusetts from Nauset Inlet to Race Point (1998-2005): U.S. Geological Survey data release, https://doi.org/10.5066/P9GWL52F.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.2463
    East_Bounding_Coordinate: -69.9406
    North_Bounding_Coordinate: 42.0825
    South_Bounding_Coordinate: 41.8193
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5f3abebd82ce8df5b6c407ac?name=CapeCod_SWASH_StudyArea_BrowseGraphic.png (PNG)
    Map showing the Cape Cod SWASH study area and reference line.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 14-Apr-1998
    Ending_Date: 02-May-2005
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: netCDF files, tabular digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
    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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is World Geodetic System 1984 (WGS 84).
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    CapeCodShorelineYYYYMMDD.*
    There are 111 netCDF (*.nc) and 111 csv (*.csv) files, each containing mean high water (MHW) shoreline data for a single Cape Cod SWASH survey. The date of each survey is indicated in the file name in YYYYMMDD format. Each netCDF and csv file includes the following data for every shoreline point: distance along the coast-following reference line at a 2-meter spacing (meters), latitude (degrees), longitude (degrees), an estimate of the beach slope near MHW (degrees), and the plus or minus horizontal uncertainty of the shoreline position (meters). MHW is defined as 0.92 m above NAVD88. (Source: USGS)
    alongshore
    Distance along the shore. (Source: USGS)
    Range of values
    Minimum:1722
    Maximum:45960
    Units:meters
    lat
    Location of the shoreline point expressed in degrees of latitude (WGS84). (Source: USGS)
    Range of values
    Minimum:41.819265
    Maximum:42.082467
    Units:decimal degrees
    lon
    Location of the shoreline point expressed in degrees of longitude (WGS84). (Source: USGS)
    Range of values
    Minimum:-70.246347
    Maximum:-69.940638
    Units:decimal degrees
    slope
    Estimated slope of the foreshore near mean high water. (Source: USGS)
    Range of values
    Minimum:0.11
    Maximum:18.73
    Units:degrees
    uncertainty
    Plus or minus horizontal uncertainty of the shoreline position in meters. (Source: USGS)
    Range of values
    Minimum:0.06
    Maximum:31.28
    Units:meters
    Entity_and_Attribute_Overview:
    The Cape Cod shoreline data are in netCDF and csv formats. The downloadable .zip file contains 111 netCDF files (one for each survey) and 111 csv files (one for each survey).
    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)
    • Amy S. Farris
    • Kathryn M. Weber
    • Jeffrey H. List
  2. Who also contributed to the data set?
    Julia Heslin, USGS, updated the study area map.
  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
    USA

    (508) 548-8700 x2344 (voice)
    (508) 457-2310 (FAX)
    afarris@usgs.gov

Why was the data set created?

Coastal erosion is a national hazard with long-term economic and social consequences. The position of the shoreline is one of the principal sources of information for local, state, and federal government agencies charged with managing coastal erosion. This measure of the shifting land/water interface is critical for quantifying impacts due to coastal storms and for understanding long-term coastal change. The SWASH system was developed by the USGS in response to a significant need for a surveying system that could provide an inexpensive, repeatable measure of shoreline position over large sections of coast within a single low tide period.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2005 (process 1 of 4)
    The SWASH system platform was a six-wheeled amphibious Max IV all-terrain vehicle, approximately 2.4 meters long, with a plastic body, enclosed cabin, and cargo bed manufactured by Recreatives Industries, Inc. of Buffalo, NY. Mounted on a custom frame were four Global Positioning System (GPS) antennas constituting the Magellan/Ashtech ADU2 array for measuring pitch, roll, and compass orientation to an accuracy of about 0.4 degrees. One of the antennas also served as the antenna for an Ashtech Z-surveyor GPS receiver. The GPS receiver, in combination with 3 base stations that were installed approximately equidistant along the length of the study area, provided position to about 4 cm accuracy.
    The SWASH system was used to collect data along 45 km of the Atlantic-exposed coast of Cape Cod, Massachusetts from Nauset Inlet in the south to Race Point spit in the north. This section of coastline is virtually unaffected by coastal development or other human activities. The beach was surveyed 111 times from April 1998 to May 2005 with a mostly bi-weekly sampling interval through February 2002. Several pre- and post-storm surveys were conducted as well.
    For each of the field surveys that were conducted, the vehicle operator navigated a single, shore-parallel track on the seaward-sloping face of the foreshore (avoiding the berm crest), estimating the position of the mean high water (MHW) contour. Surveys were conducted at low tide to allow for maximum foreshore exposure. The position (x, y, z) and slope of the vehicle were measured at 0.5-second intervals as the vehicle traversed the beach.
    This dataset was collected and processed over a span of 7 years (1998-2005). The process date represents the most recent date. 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
    Date: 2005 (process 2 of 4)
    Following the field surveys, the data were processed to determine the cross-shore location of the MHW shoreline. The elevation of MHW for the study area (0.92 m above NAVD88) was determined by local tide measurements. The GPS processing software (PNAV 2507 (Ashtech)) produced the data in geographic coordinates, and Corpscon 4.7 (U.S. Army Corps of Engineers) was used to convert the geographic coordinates to UTM eastings and northings (zone 19N, WGS84). Elevations were converted from ellipsoidal heights to orthometric heights (NAVD88) using Geoid96 (and then Geoid99 when it became available in 1999).
    A coast-following reference line was created by fitting an 8 degree polynomial to a single driven track. Perpendicular transects spaced 2 meters apart were defined along the length of the reference line. The raw GPS data were interpolated onto the transects using Matlab (ver7.1). To do this, the equation of the line defining each transect was calculated and the equation of the line between the data points on either side of each transect was found as well. These two equations were solved simultaneously and their intersection point was identified as the location of the vehicle at each transect. The measured beach elevation and slope were linearly interpolated to this point. Using simple geometry and assuming a uniform foreshore slope, shoreline position was then found along each transect by extrapolating from the vehicle location to the MHW contour.
    Outliers were identified and removed and an uncertainty estimate was computed for each shoreline point. The largest source of shoreline positional error stems from our assumption that the beach slope remained constant between the measured point and the MHW contour (termed the "uniform slope assumption"). This error is a function of the deviation between the elevation of the driven vehicle track and the MHW elevation, the measured beach slope, and an estimated mean foreshore slope variability of 1.5 degrees that was measured during tests. For each point, the beach slope was varied by 1.5 degrees to compute the most seaward and landward possible shoreline positions due to foreshore slope variability. The vertical GPS positional error was converted into a horizontal error and was added in quadrature to the error from the uniform slope assumption. This total error was divided by two to calculate the plus or minus error for each shoreline point.
    This dataset was collected and processed over a span of 7 years (1998-2005). The process date represents the most recent date. 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
    Date: 01-May-2020 (process 3 of 4)
    Using MATLAB (R2019a), the shoreline point locations were converted back into a geographic coordinate system (degrees latitude and longitude), and the data for each survey were written out to both netCDF (Network Common Data Form, netCDF 4 Classic) files and ASCII csv (American Standard Code for Information Interchange, comma-separated values) files. Each netCDF and csv file includes the following information for every shoreline point: distance along the reference line (meters), latitude (degress), longitude (degrees), an estimate of the beach slope near MHW (degrees), and the plus or minus horizontal uncertainty of the shoreline position (meters). Person who carried out this activity:
    Amy Farris
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2344 (voice)
    508-457-2310 (FAX)
    afarris@usgs.gov
    Date: 25-Jan-2021 (process 4 of 4)
    Repaired some issues that the ScienceBase turn live process introduced - removed empty elements (geospatial presentation form), in the distribution section added the additional links, access instructions, and second distribution format that had been deleted. Other elements were also adjusted such as the series information in the identification citation. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    List, Jeffrey H., and Farris, Amy S., 1999, Large-scale Shoreline Response to Storms and Fair Weather: Coastal Sediments Proceedings 1324-1338, American Society of Civil Engineers, Reston, VA.

    Online Links:

    List, Jeffrey H., Farris, Amy S., and Sullivan, Charlene, 2006, Reversing Storm Hotspots on Sandy Beaches: Spatial and Temporal Characteristics: Marine Geology 226, 261-279, Elsevier, Amsterdam, Netherlands.

    Online Links:

    List, Jeffrey H., 2013, High-Resolution Shoreline Change Measurements (1997-2005) from Corolla to Cape Hatteras, NC: Open-File Report 2011-1015, U.S. Geological Survey, Reston, VA.

    Online Links:

    This is part of the following larger work.

    Thieler, E.R., Foster, D.S., Mallinson, D.M., Himmelstoss, E.A., McNinch, J.E., List, J.H., and Hammar-Klose, E.S., 2013, Quaternary Geophysical Framework of the Northeastern North Carolina Coastal System: Open-File Report 2011-1015, 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 111 mean high water shorelines for the Outer Cape of Massachusetts. During processing, outliers in the data were removed and the uncertainty for each shoreline point was calculated as described in the process steps. Uncertainty values are included in the data files.
  2. How accurate are the geographic locations?
    The horizontal uncertainty of the post-processed derived mean high water (MHW) shoreline position is highly variable. The most significant source of error is the assumption that the foreshore slope is constant between the point of measurement and the MHW contour. This uncertainty is a function of the measured beach slope, an estimate of the cross-shore variability in foreshore slope (measured during tests), and the deviation between the elevation of the vehicle-driven track (the operator's best estimate of the MHW contour) and the measured elevation of MHW. This uncertainty, along with a smaller Global Positioning System (GPS) positional error (about 4 cm), comprise the total uncertainty for each shoreline point.
    If the vehicle was driven exactly at MHW, the horizontal uncertainty of the derived MHW position is only the GPS positioning error. If the beach is very flat and the elevation of the vehicle-driven track deviates greatly from MHW, the estimated uncertainty can be quite high (a maximum of 31.28 m was calculated). The average horizontal uncertainty calculated for the combined surveys is plus or minus 1.24 meters.
  3. How accurate are the heights or depths?
    In keeping with historical sources on shoreline information, the mean high water (MHW) contour was chosen as the definition of the shoreline. Local tide measurements were used to determine the elevation of MHW for the study area (0.92 m above NAVD88).
  4. Where are the gaps in the data? What is missing?
    All SWASH shoreline data collected between 1998 and 2005 along the Outer Cape of Massachusetts have been included in this data release.
  5. How consistent are the relationships among the observations, including topology?
    No additional checks for topological consistency were performed on this data.

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. Not for navigation.
  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 CapeCod_SWASH_Shorelines.zip contains the browse graphic CapeCod_SWASH_StudyArea_BrowseGraphic.png, the shoreline netCDF files (in CapeCod_SWASH_Shorelines_netCDF_files.zip), and the shoreline csv files (in CapeCod_SWASH_Shorelines_csv_files.zip).
  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.
    Not for navigation.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 25-Jan-2021
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)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9GWL52F/CapeCod_SWASH_Shorelines_Metadata.faq.html>
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