Elevation of salt marsh units in Edwin B. Forsythe National Wildlife Refuge, New Jersey

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Frequently anticipated questions:

What does this data set describe?

Title:
Elevation of salt marsh units in Edwin B. Forsythe National Wildlife Refuge, New Jersey
Abstract:
Elevation distribution in the Edwin B. Forsythe National Wildlife Refuge (EBFNWR), which spans over Great Bay, Little Egg Harbor, and Barnegat Bay in New Jersey, USA is given in terms of mean elevation of conceptual marsh units defined by Defne and Ganju (2016). The elevation data is based on the 1-meter resampled 1/9 arc-second resolution USGS National Elevation Data. As part of the Hurricane Sandy Science Plan, the U.S. Geological Survey is expanding National Assessment of Coastal Change Hazards and forecast products to coastal wetlands. The intent is to provide federal, state, and local managers with tools to estimate their vulnerability and ecosystem service potential. For this purpose, the response and resilience of coastal wetlands to physical factors need to be assessed in terms of the ensuing change to their vulnerability and ecosystem services. EBFNWR was selected as a pilot study area.
References: Defne, Zafer, and Ganju, N.K. 2016, Conceptual salt marsh units for wetland synthesis: Edwin B. Forsythe National Wildlife Refuge, New Jersey: U.S. Geological Survey data release, https://doi.org/10.5066/F7QV3JPG.
  1. How might this data set be cited?
    Defne, Zafer, and Ganju, Neil K., 2018, Elevation of salt marsh units in Edwin B. Forsythe National Wildlife Refuge, New Jersey: data release DOI:10.5066/F7CC0ZZZ, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Defne, Z. and Ganju, N.K., 2018, Elevation of salt marsh units in Edwin B. Forsythe National Wildlife Refuge, New Jersey: U.S. Geological Survey data release, https://doi.org/10.5066/F7CC0ZZZ
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -74.484623118
    East_Bounding_Coordinate: -74.051158122
    North_Bounding_Coordinate: 40.053798801
    South_Bounding_Coordinate: 39.435117592
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5aa6d486e4b0b1c392ed6796/?name=mu_elev_EBFNWRp.png (PNG)
    Graphic that shows conceptual marsh units of EBFNWR salt marsh complex overlaying Esri Shaded World Relief Map.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2018
    Currentness_Reference:
    Publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Vector Digital Data Set (Polygon)
  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):
      • G-polygon (1338)
    2. What coordinate system is used to represent geographic features?
      The map projection used is WGS 1984 Web Mercator Auxiliary Sphere (Esri Full Name: WGS_1984_Web_Mercator_Auxiliary_Sphere).
      Projection parameters:
      Standard_Parallel: 0.0
      Longitude_of_Central_Meridian: 0.0
      False_Easting: 0.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.6096
      Ordinates (y-coordinates) are specified to the nearest 0.6096
      Planar coordinates are specified in Meter
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      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?
    mu_elev_EBFNWRp
    Attribute information associated with the mean elevation of the conceptual marsh units of EBFNWR salt marsh complex. (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.
    FID_CMU
    Sequential unique whole numbers that represents the identification number for each conceptual marsh units. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:1337
    Units:none
    ATOT_M2
    Total surface area of a marsh unit in square meters (Source: USGS)
    Range of values
    Minimum:28.8035509447
    Maximum:7624400.41687
    Units:meters
    AVEG_M2
    Surface area of vegetated part of a marsh unit in square meters (Source: USGS)
    Range of values
    Minimum:20.5021312449
    Maximum:7076365.12545
    Units:meters
    MU_ELEV
    Mean elevation of a marsh unit in meters (Source: USGS)
    Range of values
    Minimum:0
    Maximum:7.16956289483
    Units:meters
    VG_ELEV
    Mean elevation of the vegetated area in a marsh unit in meters (Source: USGS)
    Range of values
    Minimum:0
    Maximum:7.16956289483
    Units:meters
    Entity_and_Attribute_Overview:
    In this dataset, mean elevation for each conceptual salt marsh unit in the salt marsh complex EBFNWR has been calculated based on the 1-meter resampled 1/9 arc-second horizontal resolution source dataset. Decimal values in the attribute table are a result of double precision calculations while significant digits are considered in defining the attribute measurement resolutions. Therefore, the smallest unit increment for area values and UVVR are assumed to be 1 meter and a thousandths, respectively.
    Entity_and_Attribute_Detail_Citation: USGS

Who produced the data set?

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

    508-548-8700 x2254 (voice)
    508-457-2310 (FAX)
    zdefne@usgs.gov

Why was the data set created?

Analysis of marsh elevation is part of a comprehensive assessment to identify the factors and their weights in determining the vulnerability and resiliency of salt marshes. The results are summarized over the previously determined conceptual salt marsh unit polygons (Defne and Ganju, 2016).

How was the data set created?

  1. From what previous works were the data drawn?
    marshUnitsEBFp.shp (source 1 of 2)
    Defne, Zafer, and Ganju, Neil K., 2016, Conceptual salt marsh units for wetland synthesis: Edwin B. Forsythe National Wildlife Refuge, New Jersey: data release DOI:10.5066/F7QV3JPG, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution:
    Downloaded and used the features in [marshUnitsEBFp.shp] to calculate the mean elevation for each marsh unit
    NED (source 2 of 2)
    U.S. Geological Survey, 20110215, USGS National Elevation Dataset (NED) 1/9 arc-second: U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    The following USGS NED ned19 tiles were used in analyses (11 tiles): 
    1) USGS NED ned19 n39x50_w074x50_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
2) USGS NED ned19 n39x50_w074x75_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
3) USGS NED ned19 n39x75_w074x25_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
4) USGS NED ned19 n39x75_w074x50_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
5) USGS NED ned19 n39x75_w074x75_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
6) USGS NED ned19 n40x00_w074x25_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
7) USGS NED ned19 n40x00_w074x50_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
8) USGS NED ned19 n40x00_w074x75_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
9) USGS NED ned19 n40x25_w074x25_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
10) USGS NED ned19 n40x25_w074x50_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
11) USGS NED ned19 n40x25_w074x75_nj_3coastalcounties_2011 1/9 arc-second 2012 15_x_15 minute IMG
    Type_of_Source_Media: online
    Source_Contribution:
    Elevation data from eleven USGS NED ned19 tiles (see Other Citation Details) were used in analyses. Download date was 20160801.
  2. How were the data generated, processed, and modified?
    Date: 2018 (process 1 of 2)
    This process step and all subsequent process steps were performed by the same person, Zafer Defne, in ArcMap (ver. 10.5.1) using tools from ArcToolbox, unless otherwise stated. Names of specific tools used are given in CAPITAL letters (any critical parameters used are given in parentheses, separated by a semicolon, immediately after the tool name). The input and output file names are provided in [square brackets] when necessary. Units for length and area calculations are meters (m) and square meters (m2) unless otherwise stated.
    a) Prepare elevation dataset to be clipped to the boundaries polygon. MOSAIC TO NEW RASTER(Pixel type= 32 bit float; Mosaic operator=Mean; Cellsize=1 m) all of the USGS NED 1/9 second tiles to a new raster dataset with 1m resolution. Resolution is increased from 3 m to 1 m to have a finer representation of the polygon boundaries in the horizontal during this step.
    b) Calculate values for each marsh unit. DISSOLVE(Input features=[marshUnitsEBFp]; Output=[mu_disss.shp]; Dissolve field=FID_CMU) to dissolve the vegetated and unvegetated in each marsh unit into one feature.
    c) Clip the raster with the polygon features by using EXTRACT BY MASK to obtain [elev_idw_mu.tif].
    d) ZONAL STATISTICS AS TABLE(Feature Zone Data=[marshUnitsEBFp]; zone field=FID_CMU; Value Raster=[elev_idw_mu.tif]; Output Table=mu; Statistics type=MEAN)
    e) ADD JOIN(Layer name=[marshUnitsEBFp]; Input join field=FID_CMU; Join Table=mu; Output join field=FID_CMU) to marsh units layer based on the "FID_CMU" field
    f) Export dataset as a shapefile [mu_elev.shp] and keep the 'mu_MEAN" and "mu_ATOT_M2" fields from the join operation.
    g) Calculate elevation of the vegetated areas only. SELECT BY ATTRIBUTES FROM [marshUnitsEBFp] where "CLASS"= 'vegetated'. SELECT BY ATTRIBUTES FROM [marshUnitsEBFp] where "CLASS"= 'vegetated'. Follow steps (c) to (f) using the selected features to export [veg_elev.shp].
    h) JOIN FIELD(Input table=[mu_elev.shp]; Input join field=mu_FID_CMU; Join table=[veg_elev.shp]; Output join field=vg_FID_CMU; Join fields=vg_AVEG_M2,vg_ATOT_M2,vg_MEAN). Change the field names to VG_ELEV and MU_ELEV respectively for the fields with the mean elevation for the vegetated area only and mean elevation for the entire marsh unit. Name AVEG_M2 and ATOT_M2 for vegetated and total area, respectively, and export to a new shapefile [mu_elev_EBFNWRp.shp]. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Zafer Defne
    Ocean Scientist
    384 Woods Hole Road
    Woods Hole, MA

    508-457-8700 x2254 (voice)
    508-457-2310 (FAX)
    zdefne@usgs.gov
    Data sources used in this process:
    • marshUnitsEBFp
    • NED
    Data sources produced in this process:
    • mu_elev_EBFNWRp
    Date: 07-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?
    Defne, Zafer, and Ganju, Neil K., 2016, Conceptual salt marsh units for wetland synthesis: Edwin B. Forsythe National Wildlife Refuge, New Jersey: data release DOI:10.5066/F7QV3JPG, 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?
    Water and land boundary inherit from accuracy of source data EBFNWR. Marsh units elevation value accuracy depend on vertical and horizontal accuracy of the source, National Elevation Dataset (NED).
  2. How accurate are the geographic locations?
    Horizontal accuracy is inherited from NED 1/9 second (~3-meter) dataset. Although the analyses were performed at 1-meter resolution for smoother conformity with the clipping polygons, the resolution of the final product should be considered to be greater than 3 meters.
  3. How accurate are the heights or depths?
    Vertical accuracy is inherited from NED 1/9 second (~3-meter) dataset. No additional accuracy assessment of the vertical positional information has been conducted.
  4. Where are the gaps in the data? What is missing?
    The results are specific to the marsh polygons definition within the boundaries of the EBFNWR salt marsh complex (Defne and Ganju 2016). A detailed on-the-ground analysis of a single site may result in a different interpretation of the wetland and marsh unit boundaries.
  5. How consistent are the relationships among the observations, including topology?
    Generally positive elevation means marsh unit is above sea level. There are 3 marsh units (FID_CMU= 499, 1312, 1320) which have been assigned zero elevation. These units, although classified to have regularly flooded, emergent wetland in the source dataset, are small land (less than 7000 m2), fragmented islands from mainland and receive zero elevation in NED. There are 11 marsh units (FID_CMU= 426, 427, 430, 444, 635, 1058, 1141, 1142, 1143, 1144, 1147, 1291) which have considerably high elevation (higher than 2 m) compared to the tidal range. Based on Google Maps aerial imagery these seem to be classified incorrectly as wetland in the source dataset and require ground truthing to clarify.

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 The mean elevation for each unit is defined for scientific research purposes and should not be used as a sole source of reference for any regulations and policy making. 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 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

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The zip file (mu_elev_EBFNWRp.zip) contains the shapefile mu_elev_EBFNWRp.shp (together with shapefile components, browse graphic (mu_elev_EBFNWRp.png), and associated FGDC CSDGM metadata in XML, TEXT and HTML formats with the same file name)
  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. Not for navigational use.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 19-Mar-2024
Metadata author:
U.S. Geological Survey
Attn: Zafer Defne
Ocean Scientist
384 Woods Hole Road
Woods Hole, MA

508-548-8700 x2254 (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. (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_F7CC0ZZZ/mu_elev_EBFNWRp.shp.faq.html>
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