Unvegetated to vegetated marsh ratio in Fire Island National Seashore and central Great South Bay salt marsh complex, New York

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Frequently anticipated questions:

What does this data set describe?

Title:
Unvegetated to vegetated marsh ratio in Fire Island National Seashore and central Great South Bay salt marsh complex, New York
Abstract:
Unvegetated to vegetated marsh ratio (UVVR) in the Fire Island National Seashore and central Great South Bay salt marsh complex, is computed based on conceptual marsh units defined by Defne and Ganju (2018). UVVR was calculated based on U.S. Department of Agriculture National Agriculture Imagery Program (NAIP) 1-meter resolution imagery. Through scientific efforts initiated with the Hurricane Sandy Science Plan, the U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands, including the Fire Island National Seashore and central Great South Bay salt marshes, with the intent of providing Federal, State, and local managers with tools to estimate the vulnerability and ecosystem service potential of these wetlands. 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.
References: Defne, Z., and Ganju, N.K., 2018, Conceptual marsh units for Fire Island National Seashore and central Great South Bay salt marsh complex, New York: U.S. Geological Survey data release, https://doi.org/10.5066/P95U2MQ7.
  1. How might this data set be cited?
    Defne, Zafer, and Ganju, Neil K., 2018, Unvegetated to vegetated marsh ratio in Fire Island National Seashore and central Great South Bay salt marsh complex, New York: data release DOI:10.5066/P9RHUSWY, U.S. Geological Survey, Reston, Virginia.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Defne, Z., and Ganju, N.K., 2018, Unvegetated to vegetated marsh ratio in Fire Island National Seashore and central Great South Bay salt marsh complex, New York: U.S. Geological Survey data release, https://doi.org/10.5066/P9RHUSWY.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.415467472
    East_Bounding_Coordinate: -72.746758546
    North_Bounding_Coordinate: 40.826527528
    South_Bounding_Coordinate: 40.613890619
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5bb77b87e4b0fc368e8fb9f2?name=mu_UVVR_FIISp.png (PNG)
    Graphic that shows UVVR in marsh units of FIIS salt marsh complex overlaying Esri basemap.
  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 (1130)
    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_UVVR_FIISp
    Attribute information associated with the UVVR in marsh units of FIIS 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 number that represents the identification number for each conceptual marsh units. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:1129
    Units:none
    ATOT_M2
    Total surface area of a marsh unit in square meters (Source: USGS)
    Range of values
    Minimum:25.468015
    Maximum:752436.671519
    Units:square meters
    AVEG_M2
    Surface area of vegetated part of a marsh unit in square meters (Source: USGS)
    Range of values
    Minimum:0
    Maximum:721313.980396
    Units:square meters
    UVVR
    Ratio of unvegetated surface area to vegetated surface area. Originally UVVR ranges from zero (completely vegetated) to infinity (completely unvegetated), however it is assigned the value of -1 when completely unvegetated. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:152.444580424
    Units:none
    FLG
    Marsh unit flag indicating anomalous marsh units based on absence of vegetation, elevation and surface area. FLG values indicate: (-1) no vegetated area; (-10) marsh unit elevation higher than the 99.8 percentile; (-100) marsh unit elevation less than 0.2 percentile; (-1000) marsh unit surface area less than 900 m2; and (0) no flag. Combination of negative values indicate combination of flags. For example, -1001 indicates no vegetated area and area less than 900 m2. (Source: USGS)
    Range of values
    Minimum:-1001
    Maximum:0
    Units:None
    Entity_and_Attribute_Overview:
    In this dataset, the salt marsh complex FIIS has been delineated to conceptual salt marsh units to facilitate unit by unit evaluation of response and resiliency of marsh system to physical and biogeochemical drivers. Each unit is also analyzed based on the vegetated and unvegetated surface area coverage, the ratio of which can be an independent measure of marsh health for microtidal marshes on the Atlantic and Pacific coasts of the United States. UVVR is calculated as the ratio of unvegetated area to vegetated area in a marsh unit. 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 is assumed to be 1 meter and a 0.001, 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?

The purpose of this shapefile is to calculate ratio of unvegetated area to vegetated area in each marsh unit. Analysis of unvegetated to vegetated marsh ratio is part of a comprehensive assessment to identify the factors and their weights in determining the vulnerability and resiliency of salt marshes. An unvegetated area to vegetated area ratio was defined as a potential indicator of current state of a salt marsh unit.

How was the data set created?

  1. From what previous works were the data drawn?
    CoNED (source 1 of 4)
    Danielson, Jeffrey, and Tyler, Dean, 2018, Topobathymetric Model for the New England Region States of New York, Connecticut, Rhode Island, and Massachusetts, 1887 to 2016: U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution:
    Downloaded CoNED topobathymetric data from USGS Earth Explorer. Projection was NAD 1983 UTM Zone 18N with the North American Vertical Datum of 1988 (NAVD 88). Download date was 2018/05/25.
    NAIP (source 2 of 4)
    U.S. Geological Survey, 2017, NAIP Digital Ortho Photo Image: USDA-FSA-APFO Aerial Photography Field Office, Salt Lake City, Utah.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution:
    Downloaded NAIP 1-meter resolution imagery from the USGS Earth Explorer. Projection was WGS 1984 Web Mercator Auxiliary Sphere. Download date was 2018/05/25.
    NWI (source 3 of 4)
    U.S. Fish and Wildlife Service, 2017, National Wetland Inventory New York Wetlands: U.S. Fish and Wildlife Service, Madison, WI.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution:
    Downloaded wetlands data for the state of New York in Shapefile format from the NWI download page. Projection was NAD 1983 Albers. Download date was 2018/05/25.
    CMU_FIISp.shp (source 4 of 4)
    Defne, Zafer, and Ganju, Neil K., 2018, Conceptual marsh units for Fire Island National Seashore and central Great South Bay salt marsh complex, New York: data release DOI:10.5066/P95U2MQ7, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution:
    Used the features in [CMU_FIISp.shp] to calculate the mean elevation for each marsh unit. Projection was WGS 1984 Web Mercator Auxiliary Sphere.
  2. How were the data generated, processed, and modified?
    Date: 2018 (process 1 of 4)
    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. For complex operations, 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.
    Set the data frame coordinate system and projection to NAD 1983 UTM Zone 18N. 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 CoNED raster to a new raster dataset with 1 m resolution [elev_mosaic.tif]. Person who carried out this activity:
    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
    Data sources used in this process:
    • CoNED
    Data sources produced in this process:
    • elev_mosaic
    Date: 2018 (process 2 of 4)
    Prepare mask polygon to define analysis boundaries. In order to account for the possible influence of the surrounding terrain on the analysis, first a mask area larger than the salt marsh extent is created [UVVR_mask]. At the end of the analysis the results are clipped to the boundaries of the salt marsh area [MU_mask]. Both UVVR_mask and MU_mask are edited to decide which interior polygons are removed.
    a) EXPORT features from NWI dataset after SELECT("ATTRIBUTE" LIKE 'E2%EM%' OR "ATTRIBUTE" LIKE 'E2AB3%' OR "ATTRIBUTE" LIKE 'E2EM%' OR "ATTRIBUTE" LIKE 'E2SS%' OR "ATTRIBUTE" LIKE 'E2US4%') to select from estuarine intertidal areas of 1) Emergent, 2) Scrub-shrub, 3) Rooted vascular aquatic bed, 4) Organic unconsolidated shore classes [NWI_exclusive_select.shp].
    b) BUFFER(Input features=[NWI_exclusive_select.shp]; Linear unit=5 meters; Dissolve type=All) to obtain the mask polygon [buff5m.shp] and ELIMINATE POLYGON PART(Condition=Percentage; Percentage=99; Eliminate contained part only) to obtain [UVVR_mask01.shp]. Apply buffer with -5 meters to obtain [MU_mask01.shp].
    c) EXPORT features from NWI dataset after SELECT("ATTRIBUTE" NOT LIKE 'E%' OR "ATTRIBUTE" LIKE '%FO')to obtain features that are not estuarine or are forested estuarine. MULTIPART TO SINGLEPART to separate individual polygons [NWI_inclusive_single.shp].
    d)To exclude the voids in the NWI map during the analysis these interior polygons need to be removed from the mask. Create a rectangular polygon that covers the domain [extent.shp]. ERASE [NWI_excusive_select.shp] from [extent.shp] and MULTIPART TO SINGLEPART to get [NWI_voids_single.shp].
    e) SELECT BY LOCATION from [NWI_inclusive_single.shp] that are completely within the [MU_mask01.shp], and SELECT BY LOCATION from [NWI_voids_single.shp] that are completely within the [MU_mask01.shp]. If any of additional polygons need to be removed from the mask include them in a new feature layer [erase_mask_manual.shp]. Merge all three feature sets to get polygons to be excluded [erase_inside.shp] from the final masks.
    f) ERASE [erase_inside.shp] from [MU_mask01.shp] and [UVVR_mask01.shp] to obtain [MU_mask.shp] and [UVVR_mask.shp], respectively. Data sources used in this process:
    • NWI
    Data sources produced in this process:
    • UVVR_mask
    Date: 2018 (process 3 of 4)
    Compute vegetated and unvegetated boundaries by image processing.
    a) EXTRACT BY MASK from elevation raster [elev_mosaic.tif] using [UVVR_mask.shp] polygon. Rescale the elevation raster values to the same range with 8-bit NAIP imagery (0 to 255) using min-max scaling. Perform ISO CLUSTER UNSUPERVISED CLASSIFICATION with4-bands (Near Infrared , Blue, Green, Red from the NAIP imagery and the rescaled elevation raster with 32 classes a minimum class size of 5000 cells. RECLASSIFY the classified raster by visually comparing the NAIP imagery to obtain the unvegetated-vegetated raster [UVVc.tif].
    b) Dissolve unvegetated regions smaller than a threshold value to the surrounding vegetated regions and vice versa to clean the UVV raster. For this purpose use the REGION(Number of neighbors=4; Zone grouping method=Within; Add Link field to output) to get the [UVV_region.tif], and TEST("Count" less than 9) to set a threshold value of 9 raster cells [UVV_test.tif]. Use RASTER CALCULATOR to toggle the value of the Link field in the region raster, where the test raster indicates regions with areas smaller than the threshold.
    c) RASTER TO POLYGON(Simplify polygons=False) and CLIP with the final marsh complex outline [mu_diss.shp] to obtain [UVVc_filt_clip.shp].
    d) REPAIR GEOMETRY and DISSOLVE(Create multipart features=False) to get filtered, clipped and dissolved unvegetated-vegetated polygons [UVVc_filt_clip_diss.shp].
    e) INTERSECT the dissolved conceptual marsh units [mu_diss.shp] with unvegetated-vegetated polygons [UVVc_filt_clip.shp], REPAIR GEOMETRY, and calculate the area of unvegetated and vegetated polygons in each marsh unit. To do this ADD GEOMETRY ATTRIBUTES(Geometry properties=Area_geodesic; Area unit=Square_meters) to get [UVV_poly.shp], and DISSOLVE(Input features=UVV_poly.shp; Dissolve fields=FID_CMU, gridcode; Statistics field=gridcode.MEAN, Area_geo.SUM) and REPAIR GEOMETRY to get [UVV_poly_diss.shp]. Edit the fields to have "TYP", "APGN_M2", and "ATOT_M2" fields for type of polygon indicating vegetated or unvegetated, surface area of the polygon, and total surface area of the marsh unit, respectively.
    f) Add field "UVVR" and calculate unvegetated to vegetated ratio based on "TYP", "APGN_M2" and "ATOT_M2" fields. If the vegetated area is zero for a marsh unit set the value of UVVR to -1.
    g) DISSOLVE(Input features=UVV_poly_diss.shp; Dissolve fields=FID_CMU, gridcode; Statistics field=UVVR, ATOT_M2 and FLG with Statistics type= First for all) to obtain mu_UVVR_FIIS.shp]. FLG flags anomalous marsh units based on absence of vegetation, elevation and surface area, and is set to (-1) no vegetated area; (-10) marsh unit elevation higher than the 99.8 percentile; (-100) marsh unit elevation less than 0.2 percentile; (-1000) marsh unit surface area less than 900 m2; and (0) no flag. Combination of negative values indicate combination of flags. For example, -1001 indicates no vegetated area and area less than 900 m2.
    h) SELECT BY ATTRIBUTES FROM [CMU_FIISp] where "CLASS"= 'vegetated', and join field "APGN_M2" from CMU_FIISp.shp on the feature dataset [mu_UVVR_FIIS.shp].
    i) Rearrange field names and change the projection for better performance of web services with online base maps. PROJECT(Input coordinate system=NAD 1983 UTM Zone 18N; Output coordinate system=WGS 1984 Web Mercator Auxiliary Sphere; Geographic transformation=WGS 1984 (ITRF00) to NAD 1983) the feature dataset to obtain the final conceptual marsh units [mu_UVVR_FIISp.shp]. Data sources used in this process:
    • elev_mosaic
    • CMU_FIISp
    • NAIP
    Data sources produced in this process:
    • mu_UVVR_FIISp
    Date: 07-Aug-2020 (process 4 of 4)
    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., 2018, Conceptual marsh units for Fire Island National Seashore and central Great South Bay salt marsh complex, New York: data release DOI:10.5066/P95U2MQ7, 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?
    Marsh units, water and land boundary inherit from accuracy of the source data, FIIS marsh units. Vegetated and unvegetated polygons accuracy is based on the 1-meter resolution National Agriculture Imagery Program (NAIP) products with a processing date of 2017, and 1-meter resolution U.S. Geological Survey Coastal National Elevation Database (USGS CoNED) data with processing date of 2016.
  2. How accurate are the geographic locations?
    Horizontal accuracy is inherited from the source dataset that delineates the marsh units, and can be considered to be +/-6 meters.
  3. How accurate are the heights or depths?
  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 FIIS salt marsh complex. 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?
    Topological errors that occurred during geoprocessing were automatically removed by the topological rules used for the analysis. The polygons are checked for correct geometry and do not overlap. Small polygons (less than 9 square meters) were assumed to be marginal and were assigned the classification from the surrounding majority value. A visual comparison between NAIP imagery was performed at randomly selected sites to verify the land and water boundaries. Marsh polygons without any vegetation were assigned a UVVR value of -1.

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 unvegetated to vegetated ratio for each marsh 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? mu_UVRR_FIISp
  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: 07-Aug-2020
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)
zdefne@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_P9RHUSWY/mu_UVVR_FIISp.faq.html>
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