ElevMHW: Elevation adjusted to local mean high water: Smith Island, VA, 2014

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Frequently anticipated questions:

What does this data set describe?

Title:
ElevMHW: Elevation adjusted to local mean high water: Smith Island, VA, 2014
Abstract:
Understanding how sea-level rise will affect coastal landforms and the species and habitats they support is critical for crafting approaches that balance the needs of humans and native species. Given this increasing need to forecast sea-level rise effects on barrier islands in the near and long terms, we are developing Bayesian networks to evaluate and to forecast the cascading effects of sea-level rise on shoreline change, barrier island state, and piping plover habitat availability. We use publicly available data products, such as lidar, orthophotography, and geomorphic feature sets derived from those, to extract metrics of barrier island characteristics at consistent sampling distances. The metrics are then incorporated into predictive models and the training data used to parameterize those models. This data release contains the extracted metrics of barrier island geomorphology and spatial data layers of habitat characteristics that are input to Bayesian networks for piping plover habitat availability and barrier island geomorphology. These datasets and models are being developed for sites along the northeastern coast of the United States. This work is one component of a larger research and management program that seeks to understand and sustain the ecological value, ecosystem services, and habitat suitability of beaches in the face of storm impacts, climate change, and sea-level rise.
Supplemental_Information:
For additional information on processing and use of this geospatial dataset, see the USGS Open-File report by Zeigler and others (2019).
  1. How might this data set be cited?
    Zeigler, Sara L., Sturdivant, Emily J., and Gutierrez, Benjamin T., 20191220, ElevMHW: Elevation adjusted to local mean high water: Smith Island, VA, 2014: data release DOI:10.5066/P9V7F6UX, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Sturdivant, Emily J., Zeigler, Sara L., Gutierrez, Benjamin T., and Weber, Kathryn M., 2019, Barrier island geomorphology and shorebird habitat metrics: Sixteen sites on the U.S. Atlantic Coast, 2013–2014: data release DOI:10.5066/P9V7F6UX, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Sturdivant, E.J., Zeigler, S.L., Gutierrez, B.T., and Weber, K.M., 2019, Barrier island geomorphology and shorebird habitat metrics—Sixteen sites on the U.S. Atlantic Coast, 2013–2014: U.S. Geological Survey data release, https://doi.org/10.5066/P9V7F6UX.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.92738691
    East_Bounding_Coordinate: -75.82825409
    North_Bounding_Coordinate: 37.18136655
    South_Bounding_Coordinate: 37.10935845
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5daa3801e4b09fd3b0c9cf17/?name=Elev_cei_browse.png (PNG)
    Example DEM. This example is for Cedar Island, VA and does not represent this dataset.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: Nov-2013
    Ending_Date: Jun-2014
    Currentness_Reference:
    Collection period of the source lidar data.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital dataset
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 1746 x 1614 x 1, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -75
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 5.0
      Ordinates (y-coordinates) are specified to the nearest 5.0
      Planar coordinates are specified in meters
      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 1/298.2572221010042.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: Mean High Water tidal datum from Weber and others (2005)
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Smi14_ElevMHW.tif
    Raster geospatial data file. (Source: Producer defined)
    Value
    Elevation in meters corrected to the MHW datum published by Weber and others (2005). See Weber and others (2005) for additional information on operational offsets for adjusting elevation values MHW tidal datum relative to NAVD88. Cells within the study area extent that were missing values were given a fill value of ‘9999’. Cells outside the study area extent were given a NoData value of ‘-9999’. (Source: Producer defined)
    Range of values
    Minimum:-2.12273
    Maximum:4.15863
    Entity_and_Attribute_Overview:
    The raster layer (5x5 m resolution) depicts a given location's elevation above sea-level, corrected for mean high water offset (Weber and others, 2005). This elevation layer is derived from aerial lidar. Please review Zeigler and others (2019) for detailed information. A fill value of ‘9999’ indicates cells within the study area with missing values. A NoData value of '-9999' applies to all cells outside the study area extent. Cells with fill values (9999) were used in subsequent analyses and those with NoData values (-9999) were excluded from analysis (Zeigler and others, 2019).
    Entity_and_Attribute_Detail_Citation: Methods Open-File Report by Zeigler and others (2019)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Sara L. Zeigler
    • Emily J. Sturdivant
    • Benjamin T. Gutierrez
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Sara L. Zeigler
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2290 (voice)
    508-457-2310 (FAX)
    szeigler@usgs.gov

Why was the data set created?

This digital elevation model (DEM) represents the elevation (adjusted for mean high water tidal datum) for each 5x5 m cell within the boundaries of the Smith Island, Virginia study area as measured by lidar collected in 2014. See Zeigler and others (2019) for additional details.
The DEM is part of a series of spatial datasets used to describe characteristics of barrier islands found along the North American Atlantic coast in order to identify habitat for the federally protected piping plover (Charadrius melodus). Information contained in these spatial datasets was used within a Bayesian network to model the probability that a specific set of landscape characteristics would be associated with piping plover habitat.

How was the data set created?

  1. From what previous works were the data drawn?
    DEM (source 1 of 1)
    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Geodetic Survey (NGS), Remote Sensing Division, and Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Office for Coastal Management (OCM), 20151220, 2014 NOAA Post-Sandy Topobathymetric LiDAR: Void DEMs South Carolina to New York: NOAA's Ocean Service, National Geodetic Survey (NGS), Silver Spring, MD.

    Online Links:

    Type_of_Source_Media: digital data
    Source_Contribution:
    Source elevation dataset used directly to produce this MHW elevation raster. Source data were downloaded from https://coast.noaa.gov/dataviewer in horizontal datum NAD 1983 (2011), UTM Zone 18N, vertical datum NAVD88. Downloaded on 4/8/2016.
  2. How were the data generated, processed, and modified?
    Date: 2017 (process 1 of 2)
    Full methods and justification are provided in the associated Methods OFR (Zeigler and others, 2019).
    Starting with the lidar-based source digital elevation model (DEM) for the study area, we converted the GeoTIFF file to a raster grid in ArcGIS (version 10.4.1) in the study area’s extent (as set in the geoprocessing Environment Settings). The study area boundaries were previously set using a polygon vector layer, a custom boundary that includes the entire Smith Island site relevant to the broader research program (see Zeigler and others, 2019 for more details). The study area extent has no further impacts on data contained in the final dataset presented here.
    We then resampled the resolution of the DEM (in Esri raster grid format) from 1 m to 5 m using the Resample tool in ArcToolbox version 10.4.1. In the Resample tool, we employed the bilinear resampling technique, which calculates the value of each pixel by averaging (weighted for distance) the values of the surrounding four cells.
    In Raster Calculator in ArcToolbox, we subtracted the mean high water (MHW) offset (0.34) for the Smith Island study area, as previously determined by Weber and others (2005). This process adjusts the source DEM’s original NAVD88-referenced elevation values so that 0 m elevation is MHW based on regional tidal values. See Weber and others (2005) for additional information.
    Finally, we reclassified all NoData cells in the study area to a fill value of ‘9999’. All cells outside the study area were given a NoData value of -9999, and these cells were excluded from all subsequent analyses. The distinction between fill values and NoData values allowed us to include cells with missing values–denoted by fill values–in subsequent analyses. Cells with NoData values were excluded (Zeigler and others, 2019).
    No projection transformations were required, because the source DEM was downloaded in NAD83 UTM Zone 18N.
    Date: 10-Aug-2020 (process 2 of 2)
    Added keywords section with USGS persistent identifier as theme keyword. 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?
    Zeigler, Sara L., Sturdivant, Emily J., and Gutierrez, Benjamin T., 2019, Evaluating barrier island characteristics and piping plover (Charadrius melodus) habitat availability along the U.S. Atlantic coast—Geospatial approaches and methodology: Open-File Report 2019–1071, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Details the methods used to process these data for use in barrier island and piping plover habitat modeling.
    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?
  2. How accurate are the geographic locations?
    The horizontal accuracy of the raster inherited the accuracy of the source digital elevation model (DEM), which was dependent on the accuracy of the source lidar. Refer to source contribution below for details. No projection transformations were required, because the source DEM was downloaded in NAD83 UTM Zone 18N. As such, horizontal accuracy was not affected by reprojection. The source DEM was resampled to 5-m resolution using bilinear interpolation. We estimate the accuracy of this elevation raster to be within 1 m horizontally.
    No formal accuracy assessments were conducted on the final DEM.
  3. How accurate are the heights or depths?
    The vertical accuracy of the raster inherited the accuracy of the source digital elevation model (DEM), which was dependent on the accuracy of the source lidar. Refer to source contribution below for details. The source DEM was resampled to 5-m resolution using the ‘Resample’ tool with bilinear interpolation in ArcToolbox version 10.4.1. Elevation values were adjusted to the operational mean high water (MHW) value for the region as determined by Weber and others (2005) (refer to processing descriptions below). According to Weber and others (2005), tidal datums used to calculate location-specific offsets are accurate within 6 cm.
    We estimate an overall conservative vertical accuracy of the final DEM within 1 m. However, areas with abrupt changes in elevation (e.g., a raster cell with a very low elevation adjacent to a cell with a very high elevation) may experience degraded vertical accuracy due to resampling.
    No formal accuracy assessments were conducted on the final DEM.
  4. Where are the gaps in the data? What is missing?
    This dataset is clipped to a custom boundary and may not include the entire spatial extent of the original source datasets as they are published in original form. However, the custom boundary spans the entire coverage of the Smith Island site relevant to the broader research program (see Zeigler and others, 2019 for more details). This dataset is therefore considered complete for the information presented as described in the abstract section. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    This file consists of raster data produced from elevation data and tidal datum values through a semi-automated process described below. No further logical accuracy tests were conducted on the present dataset.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None. Please see 'Distribution Info' for details.
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 (USGS) as the source of this information.
  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
    USA

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? These data files comprise a GeoTIFF (Smi14_ElevMHW.tif) file with a continuous elevation value for each 5x5 m cell. Additionally, the CSDGM FGDC metadata (Smi14_ElevMHW.tif.xml) and the browse graphic (elev_cei_browse.png) are included. These data can be downloaded individually or packaged on-demand in a zip file (see the Digital Transfer Option section).
  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. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), and have been processed successfully on a computer system at the 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. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, firm, or product 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?
    To utilize these data, the user must have software capable of reading a 32-bit GeoTIFF format.

Who wrote the metadata?

Dates:
Last modified: 19-Mar-2024
Metadata author:
Sara L. Zeigler
U.S. Geological Survey
384 Woods Hole Road
Woods Hole, MA
United States

508-548-8700 x2290 (voice)
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. (updated on 20240319)
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_P9V7F6UX/Smi14_ElevMHW.tif.faq.html>
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