Shoreline change rates in 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:
Shoreline change rates in salt marsh units in Edwin B. Forsythe National Wildlife Refuge, New Jersey
Abstract:
Monitoring shoreline change is of interest in many coastal areas because it enables quantification of land loss over time. Evolution of shoreline position is determined by the balance between erosion and accretion along the coast. In the case of salt marshes, erosion along the water boundary causes a loss of ecosystem services, such as habitat provision, carbon storage, and wave attenuation. In terms of vulnerability, higher shoreline erosion rates indicate higher vulnerability.
This dataset displays shoreline change rates at the Edwin B. Forsythe National Wildlife Refuge (EBFNWR), which spans over Great Bay, Little Egg Harbor, and Barnegat Bay in New Jersey, USA. Shoreline change rates are based on Smith and Terrano (2017) analysis of digital vector shorelines acquired from historic topographic sheets, aerial photography, and/or lidar using the AMBUR package (Jackson, 2010). Linear Regression Rates (LRR) of shoreline change were averaged along the shoreline of each salt marsh unit to generate this dataset. Positive and negative values indicate accretion and erosion respectively.
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.
  1. How might this data set be cited?
    Defne, Zafer, and Ganju, Neil K., 2018, Shoreline change rates in salt marsh units in Edwin B. Forsythe National Wildlife Refuge, New Jersey: data release DOI:10.5066/F7PN94K2, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Defne, Zafer and Ganju, N.K., 2018, Shoreline change rates in salt marsh units in Edwin B. Forsythe National Wildlife Refuge, New Jersey: U.S. Geological Survey data release, https://doi.org/10.5066/F7PN94K2
  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/59a427efe4b077f005673271?name=mu_LRR_EBFNWRp.png (PNG)
    Graphic that shows the shoreline change rate in the 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_LRR_EBFNWRp
    Attribute information associated with the shoreline change in the conceptual marsh units of EBFNWR salt marsh complex. (Source: USGS)
    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
    SHORE_LEN
    Shoreline length (Source: USGS)
    Range of values
    Minimum:0
    Maximum:2917.33158047
    Units:meters
    TRANS_PER
    Average shoreline length represented per transect. A value of -1 indicates no transect is available, and a value of 0 means the marsh unit has no shoreline. (Source: USGS)
    Range of values
    Minimum:7.742209
    Maximum:729.332895118
    Units:meters
    MEAN_LRR
    Shoreline change rate based on linear regression. A zero value may indicate: a) the rate of cahnge is actually zero, b) the marsh unit does not have shoreline (SHORE_LEN=0), or c) no transect is available for calculation (TRANS_PER=-1). (Source: USGS)
    Range of values
    Minimum:-9.29419146415
    Maximum:9.48199683803
    Units:meters/year
    Entity_and_Attribute_Overview:
    In this dataset, shoreline change is averaged over each conceptual marsh unit in EBFNWR. Negative and positive values indicate erosion and accretion, respectively. 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 shoreline change values can be assumed to be a practical value such as 0.01 meters/year.
    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)
    • 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 shoreline change is part of a comprehensive assessment to identify the factors and their weights in determining the vulnerability and resiliency of salt marshes. This polygon dataset facilitates quantifying these changes in the EBFNWR salt marsh complex by summarizing the results 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 summarize the shoreline change rates at each marsh unit
    NJ_SLC_transects (source 2 of 2)
    Kathryn E. L. Smith, and Terrano, Joseph F., 2017, Shoreline Change Analysis of Coastal and Estuarine Shorelines in Barnegat and Great Bays, NJ: 1839 to 2012: data release DOI:10.5066/F7CZ35BC, U.S. Geological Survey, Reston, Virginia.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution:
    Downloaded (version 1.1, 12/26/2017) and used the transect lines for mainland, backshore, islands and tributaries with the Linear Regression Rates (LRR) for shoreline change to calculate the shoreline change rates at each marsh unit.
  2. How were the data generated, processed, and modified?
    Date: 2017 (process 1 of 4)
    This process step used ArcMap (ver. 10.3.1) using tools from ArcToolbox. Names of specific tools used are given in CAPITAL letters (any critical parameters used is given in parentheses, separated by a semicolon, immediately after the tool name). 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.
    Shoreline change rates for EBFNWR are based on the "Shoreline Change Analysis of Coastal and Estuarine Shorelines in Barnegat and Great Bays, NJ: 1839 to 2012" by Smith and Terrano (2017) version 1.1. Download the shoreline change data, NJ_SLC_transects, for mainland (NJ_SLC_mainland.zip), estuarine barrier (NJ_SLC_backshore.zip), and islands (NJ_SLC_islands_and_tribs.zip) in Barnegat Bay, New Jersey. Use the transect shapefiles in these datasets in the following steps. Because the data are in separate files, they need to be merged and any overlapping parts need to be cleaned in order to have the values from the most relevant dataset. For example, in order to obtain mainland values exclusively from mainland transects, the transects from any other datasets that extend over the mainland are removed).
    a) Create a 100 m buffer around [tributaries_transects.shp] with BUFFER(Side type= Full; Method =Geodesic; Dissolve type= All) to obtain [trib_buff.shp].
    b) MERGE mainland and backshore transects to obtain [main+back.shp].
    c) SELECT LAYER BY LOCATION(Input feature='main+back', Relationship='Intersect', Target features='trib_buff') to select features from [main+back.shp] that intersect with buffered tributaries transects layer.
    d) Invert selection and export the dataset as [main+back_gap.shp]
    d) MERGE [tributaries_transects.shp] with [main+back_gap.shp] to obtain a data layer that covers mainland, backshore, tributaries and islands without the overlap with the tributaries, [main+back+trib.shp].
    e) Follow similar steps to remove the islands transects overlapping with the rest of the datasets. Create a 100 m buffer around [islands_transects.shp] with BUFFER(Side type= Full; Method =Geodesic; Dissolve type= All) to obtain [island_buff.shp].
    f) SELECT LAYER BY LOCATION(Input feature='main+back+trib', Relationship='Intersect', Target features='island_buff') to select features from [main+back+trib.shp] that intersect with buffered islands transects layer. g) Invert selection and export the dataset as [main+back+island_gap.shp].
    h) MERGE [islands_transects.shp] with [main+back+trib_gap.shp] to obtain [all_transects_merge.shp], which has the transects from all datasets without any overlaps.
    i) PROJECT(Geographic Transformation='WGS_1984_(ITRF00)_To_NAD_1983') the data to Web Mercator coordinate system, which is also the projection for the conceptual salt marsh units [marshUnitsEBFp.shp].
    j) ERASE the marsh polygons [marshUnitsEBFp.shp] from the transects [all_transects_merge.shp], and manually remove the transect parts that cross beyond the coastline and through multiple marsh units to obtain the final transects [all_transects.shp]. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Zafer Defne
    Ocean Scientist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2254 (voice)
    508-457-2310 (FAX)
    zdefne@usgs.gov
    Data sources used in this process:
    • marshUnitsEBFp.shp
    Data sources produced in this process:
    • all_transects.shp
    Date: 2017 (process 2 of 4)
    Calculate shoreline length for each marsh unit.
    a) Prepare the shorelines to be selected by POLYGON TO POLYLINE(Input features='marshUnitsEBFp.shp'; Output feature class='mu_clean_line.shp'). Convert MULTIPART TO SINGLEPART(Input features='mu_clean_line.shp'; Output feature class='mu_clean_line_single.shp').
    b) Prepare the polyline to be used for selecting. First create the outline by DISSOLVE(Input features='marshUnitsEBFp.shp'; Output feature class='mu_clean_diss.shp') and POLYGON TO POLYLINE(Input features='mu_clean_diss.shp'; Output feature class='mu_clean_diss_line.shp')
    c) Use select by location menu to select from [mu_clean_line_single.shp] that intersect with [mu_clean_diss_line.shp] and export it to [mu_shoreline.shp]. Manually edit the layer to remove the outlines that are not shorelines.
    d) ADD GEOMETRY ATTRIBUTES(Geometry properties='length_geodesic'; Length unit='meters') to [mu_shoreline.shp]. Calculate the shoreline length per marsh unit by DISSOLVE(Dissolve field='FID_CMU'; STATISTICS='SUM') to get [mu_shoreline_length.shp].
    e) JOIN FIELD(Input table='marshUnitsEBFp.shp'; Input join field='FID_CMU'; Join table='mu_shoreline_length.shp'; Output join field='FID_CMU'), Join fields='SUM_LENGTH')
    f) EXPORT joined marshUnitsEBFp.shp with shoreline length data to [mu_clean_with_shorelength] Data sources used in this process:
    • marshUnitsEBFp.shp
    Data sources produced in this process:
    • mu_clean_with_shorelength.shp
    Date: 2017 (process 3 of 4)
    Calculate the transect coverage and mean LRR shoreline change in each marsh unit. Transect coverage is the average shoreline length represented by the transects in a marsh unit.
    a) SPATIAL JOIN(Target features='mu_clean_with_shorelength.shp'; Join features='all_transects.shp'; Output features='mu_trans_join.shp';Join_one_to_many; Match option='INTERSECT') to assign LRR values to the intersecting marsh units.
    b) Calculate the mean LRR for each marsh unit with SUMMARY STATISTICS(Input table='mu_trans_Join.shp'; Output_table='s'; Statistics Fields=LRR; Statistics type='MEAN'; Case field='TARGET_FID').
    c) Calculate total number of transects intersecting the shoreline with SUMMARY STATISTICS. ADD the TRANS_PER field and calculate it as the total shoreline length divided by the number of transects. Assign a value of -1 if the number of transects is equal to zero.
    d) Assign the calculated mean LRR to each marsh unit with ADD JOIN(Layer name='marshUnitsEBFp'; Input join field='FID_CMU'; Join table='s'; Output join field='TARGET_FID', Keep_all_target_features). Assign the shoreline length and transect coverage fields similarly.
    e) Edit the attribute table to choose fields to keep and to format the field names. Export the dataset as final output [mu_LRR_EBFNWRp.shp] Data sources used in this process:
    • mu_clean_with_shorelength.shp
    • all_transects.shp
    Data sources produced in this process:
    • mu_LRR_EBFNWRp.shp
    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., 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, Virginia.

    Online Links:

    Jackson, C.W., Jr., 2010, Basic User Guide for the AMBUR package for R, version 1.0a.

    Online Links:

    Kathryn E. L. Smith, and Terrano, Joseph F., 2017, Shoreline Change Analysis of Coastal and Estuarine Shorelines in Barnegat and Great Bays, NJ: 1839 to 2012: data release DOI:10.5066/F7CZ35BC, U.S. Geological Survey, Reston, Virginia.

    Online Links:

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

  1. How well have the observations been checked?
    Water-land boundary and marsh unit boundaries inherit from accuracy of the source data, the conceptual salt marsh units. Shoreline change rate is calculated by averaging the values from the source layer (shoreline change transects drawn at every ~50 meters from baseline) per each marsh unit. Shoreline change rates in the source data are influenced by availability and accuracy of shoreline data. It is noted in the source dataset that analyses of highly dynamic areas are particularly challenging, including 1) areas near inlets, where there is excessively dynamic depositional/erosional sand bars that may appear/disappear rapidly, and 2) stretches of backshore where overwash fans can form islands that are difficult to resolve and distinguish from barrier islands themselves. Where shorelines experience sharp bends, such as in small bays and narrow spits, the filter algorithm can create transects that are not perpendicular to the shoreline. This issue was found to affect the accuracy of the LRR values specifically for the marsh units on the barrier island to the south of Little Egg Inlet (39.492N, 74.315W; especially for marsh units with FID_CMU = 1001, 1002, 1025, 1042, 1052).
  2. How accurate are the geographic locations?
    Horizontal accuracy for the polygon boundaries is inherited from the source layer, the conceptual salt marsh units, and considered to be better than ~3 meters.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    The polygon outlines for this dataset are defined by the conceptual marsh unit boundaries in the source dataset. A detailed on-the-ground analysis of a single site may result in a different interpretation of the wetland and marsh unit boundaries. All of the marsh units are assigned a value. If MEAN_LRR is 0 for a marsh unit, 0 in the TRANS_PER field indicates the marsh unit has no shoreline and -1 indicates there are no transects available.
  5. How consistent are the relationships among the observations, including topology?
    Mean Linear Regression Rate (LRR) shoreline change is calculated by averaging the LRR transects that cross the shoreline of a marsh unit. The transects were checked for crossing only the marsh unit they are assigned to and not others. A specific case is to the north of Little Egg Inlet, where the barrier island and the sand bar behind it were not distinguished in the source data. Therefore, the LRR values at this location were excluded. If a marsh unit has no shoreline the mean LRR is set to zero. If a marsh unit has a shoreline, but no transect is available to assign a shoreline change rate the mean LRR is also set to zero. However, it is indicated by a value of -1 in TRANS_PER field, which is originally used to display the average shoreline length represented per transect.

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 shoreline change rates in this dataset are 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_LRR_EBFNWRp.shp (together with shapefile components, browse graphic, 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_F7PN94K2/mu_LRR_EBFNWRp.shp.faq.html>
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