Unvegetated to vegetated ratio of marsh units in Maine salt marshes

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• 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?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
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  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Ackerman, Kate V., Defne, Zafer, and Ganju, Neil K., 20240129, Unvegetated to vegetated ratio of marsh units in Maine salt marshes: data release DOI:10.5066/P9FRGLB0, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

   Online Links:

   • https://doi.org/10.5066/P9FRGLB0
   • https://www.sciencebase.gov/catalog/item/657b3f0cd34e952b2274bb3d

   This is part of the following larger work.
   Ackerman, Kate V., Defne, Zafer, and Ganju, Neil K., 2024, Geospatial characterization of salt marshes in Maine: data release DOI:10.5066/P9FRGLB0, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9FRGLB0
   • https://www.sciencebase.gov/catalog/item/657b3ac7d34e952b2274ba98

   Other_Citation_Details:

   Suggested citation: Ackerman, K.V., Defne, Z., and Ganju, N.K., 2024, Geospatial characterization of salt marshes in Maine: U.S. Geological Survey data release, https://doi.org/10.5066/P9FRGLB0.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -70.828578
   East_Bounding_Coordinate: -66.984779
   North_Bounding_Coordinate: 45.096044
   South_Bounding_Coordinate: 43.069179
   

3. What does it look like?

   https://www.sciencebase.gov/catalog/file/get/657b3f0cd34e952b2274bb3d/?name=UVVR_ME_Browse.png&allowOpen=true (PNG)

   Graphic that shows UVVR of conceptual marsh units in Maine salt marshes.

4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 2024

   Currentness_Reference:

   publication date

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: vector digital dataset (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 (4627)
   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:

      False_Easting: 0.0
      False_Northing: 0.0
      Longitude_of_Central_Meridian: 0.0
      Standard_Parallel: 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 meters
      The horizontal datum used is D_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?

   mu_UVVR_ME.shp

   Table containing attribute information associated with the dataset. (Source: USGS)

   FID

   Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.

   Shape

   Feature geometry. (Source: Esri) Feature geometry. Marsh units are polygon features.

   FID_CMU

   Unique whole numbers used to identify each conceptual marsh unit. (Source: USGS)

   Range of values
   Minimum:	0
   Maximum:	4626

   ATOT_M2

   Total surface area of a marsh unit in square meters. (Source: USGS)

   Range of values
   Minimum:	109.38287
   Maximum:	1374107.4756
   Units:	square meters

   AVEG_M2

   Surface area of the vegetated part of a marsh unit in square meters. (Source: USGS)

   Range of values
   Minimum:	0.0
   Maximum:	592657.336254
   Units:	square meters

   UVVR

   Ratio of unvegetated surface area to vegetated surface area. Ordinarily, 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:	-1.0
   Maximum:	1029.57435
   Units:	none

   FLG

   Marsh unit flag indicating anomalous marsh units based on absence of vegetation, elevation, surface area and tidal range extrapolation. FLG values indicate: (-1) no vegetated area in the marsh unit; (-10) marsh unit elevation higher than the 99.8 percentile; (-100) marsh unit elevation less than the 0.2 percentile; (-200) greater than 25 percent of the marsh unit elevation is hydro-flattened; (-1000) marsh unit surface area less than 900 square meters; (-10000) mean tidal range of marsh unit is extrapolated; and (0) no flag. Combination of negative values indicates a combination of flags. For example, -1001 indicates no vegetated area and area less than 900 square meters. (Source: USGS)

   Range of values
   Minimum:	-11201
   Maximum:	0
   Units:	none

   Entity_and_Attribute_Overview:

   In this dataset, the salt marshes across Maine have been delineated to conceptual salt marsh units to facilitate unit by unit evaluation of response and resiliency of the 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 salt 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 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)
   • Kate V. Ackerman
   • Zafer Defne
   • Neil K. Ganju
2. Who also contributed to the data set?
3. To whom should users address questions about the data?
   Kate Ackerman

   U.S. Geological Survey

   Geologist

   384 Woods Hole Road

   Woods Hole, MA
   

   US

   508-548-8700 x2331 (voice)

   508-457-2310 (FAX)

   kackerman@usgs.gov

Why was the data set created?

How was the data set created?

1. From what previous works were the data drawn?

   ME DEM (source 1 of 7)

   U.S. Geological Survey, 2023, 3D Elevation Program (3DEP): U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://apps.nationalmap.gov/downloader/

   Other_Citation_Details:

   These data were published on multiple dates between March 2020 and March 2023. Downloaded 1-meter DEM. Projection was NAD 1983 UTM Zone 19N referenced to the North American Vertical Datum of 1988 (NAVD88). Multiple download dates between 2/28/2023 and 9/12/2023.

   Type_of_Source_Media: Digital
   Source_Contribution: Elevation dataset
   

   ME DEM 2 (source 2 of 7)

   U.S. Geological Survey, 2011, National Elevation Dataset (NED): U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://apps.nationalmap.gov/downloader/

   Other_Citation_Details:

   Downloaded 1/9 arc-second DEM for a few very small areas not covered by the 1 meter DEM. The data is distributed in geographic coordinates (NAD83), referenced to the North American Vertical Datum of 1988 (NAVD88). Download date was 9/12/2023.

   Type_of_Source_Media: Digital
   Source_Contribution: Elevation dataset
   

   NAIP 2018 (source 3 of 7)

   U.S. Department of Agriculture, 2018, NAIP Digital Ortho Photo Image: USDA-FSA-APFO Aerial Photography Field Office, Salt Lake City, Utah.

   Online Links:

   • https://earthexplorer.usgs.gov

   Other_Citation_Details:

   Downloaded NAIP 4-band, 0.6-meter resolution imagery from the USGS Earth Explorer. Projection was NAD 1983 UTM Zone 19N. Download date was 04/01/2022.

   Type_of_Source_Media: Digital
   Source_Contribution: Aerial imagery dataset
   

   NAIP 2021 (source 4 of 7)

   U.S. Department of Agriculture, 2021, NAIP Digital Ortho Photo Image: USDA-FSA-APFO Aerial Photography Field Office, Salt Lake City, Utah.

   Online Links:

   • https://earthexplorer.usgs.gov

   Other_Citation_Details:

   Downloaded NAIP 4-band, 0.6-meter resolution imagery from the USGS Earth Explorer. Projection was NAD 1983 UTM Zone 19N. Download date was 04/01/2022.

   Type_of_Source_Media: Digital
   Source_Contribution: Aerial imagery dataset
   

   NWI (source 5 of 7)

   U.S. Fish and Wildlife Service, 20220501, National Wetland Inventory: U.S. Fish and Wildlife Service, Madison, WI.

   Online Links:

   • https://www.fws.gov/wetlands/data/Data-Download.html

   Other_Citation_Details:

   Downloaded wetlands data for Maine in shapefile format from the NWI download page. Projection was NAD 1983 Albers. Download date was 09/23/2022.

   Type_of_Source_Media: Digital
   Source_Contribution: Wetlands dataset
   

   MNAP (source 6 of 7)

   Maine Department of Agriculture, Conservation and Forestry, 2014, Maine Natural Areas Program Tidal Marshes Map: Maine Department of Agriculture, Conservation and Forestry, Augusta, ME.

   Online Links:

   • https://www.maine.gov/dacf/mnap/assistance/tidal_marshes.htm

   Other_Citation_Details:

   Downloaded 2014 tidal marsh layer in shapefile format. Projection was NAD 1983 UTM Zone 19N. Download date was 05/01/2022.

   Type_of_Source_Media: Digital
   Source_Contribution: Wetlands dataset
   

   CMU_ME (source 7 of 7)

   Ackerman, K.V., Defne, Z., and Ganju, N.K., 2024, Conceptual marsh units of Maine salt marshes, in Geospatial characterization of salt marshes in Maine: data release DOI:10.5066/P9FRGLB0, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://www.sciencebase.gov/catalog/item/657b3ea5d34e952b2274bb2f
   • https://doi.org/10.5066/P9FRGLB0

   Other_Citation_Details:

   This dataset (Conceptual marsh units of Maine salt marshes) is within the larger data release (Geospatial characterization of salt marshes in Maine). The first link below is to the conceptual marsh units data and the second link is to the data release.

   Type_of_Source_Media: Digital
   Source_Contribution:

   Used conceptual marsh units, generated as part of this data release, to delineate marsh unit boundaries.

2. How were the data generated, processed, and modified?

   Date: 2023 (process 1 of 3)

   This process step and all subsequent process steps were performed by the same person, Kate Ackerman, in ArcGIS Pro (ver. 2.8.8), unless otherwise stated. For simple operations the name of the geoprocessing tool used is given in capital letters; for complex operations, the name of the geoprocessing tool used is given in capital letters and 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 unless otherwise stated.
   a) Set the data frame coordinate system and projection to NAD 1983 UTM Zone 19N.
   b) Establish marsh unit boundaries. Dissolve the vegetated and unvegetated classes in each marsh unit to have only one class for each marsh unit. DISSOLVE (Input features=[CMU_ME.shp]; Dissolve field=FID_CMU; Statistics field=ATOT_M2 and FLG with Statistics type= First). PROJECT (Input coordinate system=WGS 1984 Web Mercator Auxiliary Sphere; Output coordinate system=NAD 1983 UTM Zone 19N) the feature dataset to obtain dissolved marsh units [mu_diss.shp].
   c) Prepare elevation dataset. Combine all downloaded tiles into one raster, using MOSAIC TO NEW RASTER, and PROJECT RASTER to NAD 1983 UTM Zone 19N.
   d) Create a polygon that covers the area of interest [extent.shp]. CLIP the mosaicked elevation dataset created in step (c) by [extent.shp] to create [elev_mosaic.tif]. Person who carried out this activity:
   

   Kate Ackerman

   U.S. Geological Survey

   Geologist

   384 Woods Hole Road

   Woods Hole, MA
   

   US

   508-548-8700 x2331 (voice)

   508-457-2310 (FAX)

   kackerman@usgs.gov

   Data sources used in this process:

   • ME DEM
   • ME DEM 2
   • CMU_ME

   Data sources produced in this process:

   • elev_mosaic.tif
   • mu_diss.shp

   Date: 2023 (process 2 of 3)

   This process step creates two mask polygons to define analysis boundaries over the area of interest. In order to account for the possible influence of the surrounding terrain on the analysis, a mask area larger than the salt marsh extent is created [UVVR_mask.shp]. This larger mask area is clipped to the boundaries of the salt marsh area to create [MU_mask.shp]. This process step explains how [UVVR_mask.shp] and [MU_mask.shp] are created and edited to determine which interior polygons are removed.
   a) Create a shapefile of the salt marshes as defined by NWI. From the NWI dataset of all wetlands for the area (referred to as [NWI_entire.shp]), select estuarine intertidal areas of 1) emergent wetland, 2) scrub-shrub area, 3) rooted vascular aquatic bed, and 4) organic unconsolidated shore classes (SELECT (ATTRIBUTE LIKE 'E2%EM%' OR ATTRIBUTE LIKE 'E2AB3%' OR ATTRIBUTE LIKE 'E2EM%' OR ATTRIBUTE LIKE 'E2SS%' OR ATTRIBUTE LIKE 'E2US4%'). EXPORT features (in the same coordinate system as the data frame) to create [NWI_exclusive_select.shp]. In some areas, erroneous line features were eliminated or modified to allow the salt marsh extent to be consistent with imagery.
   b) Create the preliminary masks that will be edited in the subsequent steps to make the final masks. BUFFER salt marsh classes (Input features=[NWI_exclusive_select.shp]; Linear unit=5 meters; Dissolve type=All) to obtain the mask polygon [buff5m.shp] and ELIMINATE POLYGON PART (Input features= [buff5m.shp]; Condition=Percentage; Percentage=99; Eliminate contained part only) to remove small interior polygons to obtain [UVVR_mask01.shp]. Apply BUFFER (Input features=[UVVR_mask01.shp]; Linear unit= -5 meters; Dissolve type= All) to obtain [MU_mask01.shp].
   c) Create a shapefile of features that are not estuarine or are forested estuarine (SELECT (ATTRIBUTE NOT LIKE 'E%' OR ATTRIBUTE LIKE '%FO')) from the NWI dataset. EXPORT features to create [NWI_inclusive_select.shp]. 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. ERASE [NWI_exclusive_select.shp] from [extent.shp] and MULTIPART TO SINGLEPART to get [NWI_exc_voids_single.shp].
   To create the final mask shapefiles ([MU_mask.shp] and [UVVR_mask.shp]), areas that should not be included are removed (e.g., forest areas), and areas that should be included are incorporated (estuarine and marine wetland systems that are completely surrounded by salt marsh (e.g., interior ponds)):
   e)SELECT BY LOCATION from [NWI_inclusive_single.shp] that are completely within the [MU_mask01.shp] and SELECT BY LOCATION from [NWI_exc_voids_single.shp] that are completely within the [MU_mask01.shp]. UNION all feature sets to get polygons to be excluded [erase_inside.shp] from the final masks.
   f) Spatially join the [NWI_entire.shp] to [erase_inside.shp] in order to assign wetland attributes to the [erase_inside.shp] polygons. SPATIAL JOIN (target features= [erase_inside.shp]; join features= [NWI_entire.shp]; output feature class= [erase_inside_NWI_info.shp]; join operation= one to one; keep all target features; match option= intersect; search radius= -1 m).
   g) Select the polygons that are marine or non-forested estuarine wetlands from [erase_inside_NWI_info.shp]: SELECT (ATTRIBUTE LIKE 'E1%' OR ATTRIBUTE LIKE 'E2AB%' OR ATTRIBUTE LIKE 'E2RF%' OR ATTRIBUTE LIKE 'E2SB%' OR ATTRIBUTE LIKE 'E2RS%' OR ATTRIBUTE LIKE 'E2US%' OR ATTRIBUTE LIKE 'E2EM%' OR ATTRIBUTE LIKE ‘E2SS%’ OR ATTRIBUTE LIKE ‘M1%’ OR ATTRIBUTE LIKE ‘M2%) to select all marine systems, estuarine subtidal systems, estuarine intertidal areas of aquatic bed, reef, streambed, rocky shore, unconsolidated shore, emergent, or scrub-shrub [erase_inside_keepIntPonds.shp].
   h) Remove the polygons from [erase_inside_NWI_info.shp] that should be retained (these are the interior ponds): ERASE (input feature= [erase_inside_NWI_info.shp]; erase feature= [erase_inside_keepIntPonds.shp]; output feature= [erase_inside_final.shp]).
   i) If any additional polygons need to be removed from the mask, include them in a new feature layer [erase_mask_manual.shp] and MERGE with [erase_inside_final.shp].
   j) Remove any unwanted polygons from the original [MU_mask01.shp] to make the final [MU_Mask.shp]: ERASE (input feature= [MU_mask01.shp]; erase feature= [erase_inside_final.shp]; output feature= [MU_mask.shp]).
   k) Use the MNAP tidal marsh boundaries to refine, and in some cases, replace polygons in [MU_mask.shp] that are not consistent with aerial imagery.
   l) BUFFER [MU_mask.shp] by 5m (side type= full; end type= round; method: geodesic; dissolve type: single feature) to obtain [UVVR_mask.shp]. Data sources used in this process:

   • NWI
   • MNAP

   Data sources produced in this process:

   • MU_mask.shp
   • UVVR_mask.shp

   Date: 2023 (process 3 of 3)

   Compute vegetated and unvegetated areas by image processing.
   a) MOSAIC TO NEW RASTER the NAIP tiles.
   b) EXTRACT BY MASK from the elevation raster [elev_mosaic.tif] and the NAIP imagery raster using [UVVR_mask.shp] polygon and append “UVVR_mask” to the file name. Rescale the elevation raster values to the same range with 8-bit NAIP imagery (0 to 255) using min-max scaling in RASTER CALCULATOR (map algebra expression: (("elev_mosaic_UVVR_mask.tif"-(min value of the input raster))*(255-0)/(max value of the input raster)-( min value of the input raster)))+0). Perform ISO CLUSTER UNSUPERVISED CLASSIFICATION with 5 input bands: the Near Infrared, Blue, Green, and Red from the NAIP imagery and the rescaled elevation raster; with 32 classes and a minimum class size of 500 cells. RECLASSIFY the classified raster by visually comparing the NAIP imagery to obtain the unvegetated-vegetated raster [UVVc.tif]. In some regions, a couple of the 32 classes are classified as vegetated in one area but unvegetated in another area. For these classes, the area can be split into separate sections to allow one section to be classified as vegetated and the other as unvegetated.
   c) 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 GROUP (Number of neighbors=4; Zone grouping method=Within; Add Link field to output) to get the [UVV_region.tif], and TEST("Count" < 9) to set a threshold value of 9 raster cells [lt9.tif]. Use RASTER CALCULATOR to toggle the value of the Link field in the region raster [Map algebra expression=Con("%lt9.tif%", ~Lookup("%UVVc_region.tif%","LINK"),Lookup("%UVVc_region.tif%","LINK"))], where the test raster indicates regions with areas smaller than the threshold.
   d) RASTER TO POLYGON (Simplify polygons=False) and CLIP with the final marsh complex outline [mu_diss.shp] to obtain [UVVc_filt_clip.shp].
   e) REPAIR GEOMETRY, ADD GEOMETRY ATTRIBUTES (Geometry properties=Area_geodesic; Area unit=Square_meters), CALCULATE FIELD (Python_9.3 expression; Field name=gridcode, Expression=filt(!gridcode!, !AREA_GEO!), Code Block= def filt(gridcode, AREA_GEO):/if gridcode== 0 and AREA_GEO < 9:/return 1/else:/return gridcode) and DISSOLVE( Create multipart features=False) to get filtered, clipped and dissolved unvegetated-vegetated polygons [UVVc_filt_clip_diss.shp].
   f) INTERSECT the final conceptual marsh units [mu_diss.shp] with unvegetated-vegetated polygons [UVVc_filt_clip_diss.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) and REPAIR GEOMETRY to get [UVV_poly_diss.shp]. Add fields "TYP", "APGN_M2", and "ATOT_M2" for type of polygon indicating vegetated or unvegetated, surface area of the polygon, and total surface area of the marsh unit, respectively, and calculate "APGN_M2" and "ATOT_M2" areas.
   g) Visually inspect and manually remove marsh units that are a result of geoprocessing artifacts (e.g., buffering).
   h) 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.
   i) DISSOLVE (Input features=[UVV_poly_diss.shp]; Dissolve fields=FID_CMU; Statistics field=UVVR, ATOT_M2 and FLG with Statistics type= First for all) to obtain [mu_UVVR_ME.shp].
   j) SELECT BY ATTRIBUTES FROM [CMU_ME.shp] where "TYP"= 'vegetated,' and join field "APGN_M2" from [CMU_ME.shp] to [mu_UVVR_ME.shp] and rename this field "AVEG_M2."
   k) Add field "FLG" to flag anomalous marsh units based on absence of vegetation, elevation, surface area, and tidal range extrapolation. The flags are calculated in their respective shapefile (i.e., elevation flags are calculated in the elevation shapefile). Set FLG to (-1) no vegetated area in the marsh unit; (-10) marsh unit elevation higher than the 99.8 percentile; (-100) marsh unit elevation less than the 0.2 percentile; (-200) greater than 25 percent of the marsh unit elevation is hydro-flattened; (-1000) marsh unit surface area less than 900 square meters; (-10000) mean tidal range of marsh unit is extrapolated; and (0) no flag. Combination of negative values indicates a combination of flags; for example, -1001 indicates no vegetated area and area less than 900 square meters.
   l) Rearrange fields and change the projection for better performance of web services with online base maps. PROJECT (Output coordinate system=WGS 1984 Web Mercator Auxiliary Sphere) the feature dataset to obtain the UVVR for each marsh unit [mu_UVVR_ME.shp]. Data sources used in this process:

   • elev_mosaic.tif
   • NAIP 2018
   • NAIP 2021

   Data sources produced in this process:

   • mu_UVVR_ME.shp

3. What similar or related data should the user be aware of?
   Ganju, N.K., Defne, Z., and Fagherazzi, S., 2020, Are elevation and open-water conversion of salt marshes connected?: Geophysical Research Letters v. 47, issue 3.

   Online Links:

   • https://doi.org/10.1029/2019GL086703

   Other_Citation_Details:

   For more information about the UVVR, please see this publication.

   Defne, Z., Aretxabaleta, A.L., Ganju, N.K., Kalra, T.S., Jones, D.K., and Smith, K.E.L., 2020, A geospatially resolved wetland vulnerability index: Synthesis of physical drivers: PLoS ONE 15 (1).

   Online Links:

   • https://doi.org/10.1371/journal.pone.0228504

   Other_Citation_Details:

   For more information about the UVVR, please see this publication.

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?
   Marsh units and water and land boundaries inherit their accuracy from the U.S. Fish and Wildlife Service National Wetland Inventory (USFWS NWI). However, the lineage of the source data indicates that the underlying data span multiple years and the mapped features may have changed since the date of imagery. In conjunction with the NWI boundaries, the Maine Natural Areas Program (MNAP) tidal marshes boundaries were used to delineate marshes throughout Maine. Accuracy of marsh unit delineation depends on the vertical and horizontal accuracy of the elevation data (ME DEM). Accuracy of the vegetated and unvegetated polygons is based on the National Agriculture Imagery Program (NAIP) products from 2018 and 2021 (0.6-meter resolution). Any vegetated or unvegetated polygons less than 9 square meters were merged with the surrounding majority class unless they are at the edge of a marsh unit. When creating marsh units, conterminous polygons smaller than 900 square meters were merged with the larger polygon of the same type.
2. How accurate are the geographic locations?
   Horizontal accuracy for the polygon boundaries is inherited from the source layer, the conceptual marsh units, and is 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 marsh polygons are bound to the borders of Maine's estuarine intertidal areas that include: 1) emergent wetlands, 2) scrub-shrub areas, 3) rooted vascular aquatic beds, 4) organic unconsolidated shores, and 5) channels of open water that are narrower than 10 meters. Occasionally, marsh units are retained in this dataset even though the imagery displayed extreme change (e.g., partially or completely converted to water) from the NWI wetland delineation (e.g., marsh units 2345, 3745). In a few areas, there are no marsh units where there is visible marsh plain (e.g., northwest of marsh unit 1824), because the areas are classified in the NWI as estuarine subtidal unconsolidated shore, which is not included as salt marsh in this analysis. In a few locations, there may be areas that that are classified as unvegetated but are in fact very sparsely vegetated. A detailed on-the-ground analysis of a single site may result in a different interpretation of the wetland and marsh unit boundaries than those established through this analysis.
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 were 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.

How can someone get a copy of the data set?

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_UVVR_ME.zip (ZIP file contains the shapefile mu_UVVR_ME.shp and the additional shapefile components), a browse graphic (UVVR_ME_Browse.png) and FGDC CSDGM metadata in xml format.
3. What legal disclaimers am I supposed to read?
   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 for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
4. How can I download or order the data?
   • Availability in digital form:

     Data format:	This dataset contains a polygon shapefile and its components and metadata in xml format. in format shapefile (version ArcGIS Pro 2.8.8) Size: 12
     Network links:	https://www.sciencebase.gov/catalog/file/get/657b3f0cd34e952b2274bb3d https://www.sciencebase.gov/catalog/item/657b3f0cd34e952b2274bb3d https://doi.org/10.5066/P9FRGLB0

     Data format:	WMS
     Network links:	https://www.sciencebase.gov/catalogMaps/mapping/ows/657b3f0cd34e952b2274bb3d?service=wms&request=getcapabilities&version=1.3.0

     Data format:	WFS
     Network links:	https://www.sciencebase.gov/catalogMaps/mapping/ows/657b3f0cd34e952b2274bb3d?service=wfs&request=getcapabilities&version=1.0.0

   • Cost to order the data: None. No fees are applicable for obtaining the dataset.

Who wrote the metadata?

Dates:

Last modified: 29-Jan-2024

Metadata author:

Kate V. Ackerman

U.S. Geological Survey

Geologist

384 Woods Hole Rd

Woods Hole, MA

US

508-548-8700 x2331 (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.

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)