Wave power on marsh units in Connecticut salt marshes

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Frequently anticipated questions:

What does this data set describe?

Title: Wave power on marsh units in Connecticut salt marshes
Abstract:
This data release contains coastal wetland synthesis products for the state of Connecticut. Metrics for resiliency, including the unvegetated to vegetated ratio (UVVR), marsh elevation, tidal range, wave power, and exposure potential to environmental health stressors are calculated for smaller units delineated from a digital elevation model, providing the spatial variability of physical factors that influence wetland health. The U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands 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. This project has been funded in part by the United States Environmental Protection Agency under assistance agreement DW-014-92531201-1 to N. Ganju.
  1. How might this data set be cited?
    Ackerman, Kate V., Defne, Zafer, and Ganju, Neil K., 20231023, Wave power on marsh units in Connecticut salt marshes: data release DOI:10.5066/P96QND48, 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.

    Ackerman, Kate V., Defne, Zafer, and Ganju, Neil K., 2023, Geospatial characterization of salt marshes in Connecticut: data release DOI:10.5066/P96QND48, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Ackerman, K.V., Defne, Z., and Ganju, N.K., 2023, Geospatial characterization of salt marshes in Connecticut: U.S. Geological Survey data release, https://doi.org/10.5066/P96QND48.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.658477
    East_Bounding_Coordinate: -71.831904
    North_Bounding_Coordinate: 41.532199
    South_Bounding_Coordinate: 40.983874
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/64c40b03d34e70357a33d432/?name=WavePower_CT_Browse.png&allowOpen=true (PNG)
    Graphic that shows wave power on conceptual marsh units in Connecticut salt marshes.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2023
    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 (2499)
    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_WavePower_CT.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:2498
    Units:none
    WavePwr
    The wave power (energy per unit length) generated by the movement of ocean waves, averaged over a marsh unit. (Source: USGS)
    Range of values
    Minimum:0
    Maximum:94.0957336426
    Units:Watts/meter
    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:-11200
    Maximum:0
    Units:none
    Entity_and_Attribute_Overview:
    In this dataset, mean wave power (the energy per unit length created by the motion of waves) for each conceptual marsh unit in Connecticut salt marshes has been calculated.
    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?

The purpose of this shapefile is to provide the wave power for each marsh unit. Analysis of wave power is part of a comprehensive assessment to identify the factors and their weights in determining the vulnerability and resiliency of salt marshes. Wave power, which is extracted from a grid derived from model simulations, is the energy per unit length generated by the movement of ocean waves. The wave power for individual marsh units uses a conservative interpolation that relies on the grid resolution of the model simulation. This dataset displays the spatial variation of wave power across marsh units in Connecticut salt marsh complexes.

How was the data set created?

  1. From what previous works were the data drawn?
    Wave Power (source 1 of 2)
    Aretxabaleta, A.L., Defne, Z., Kalra, T.S., Blanton, B.O., and Ganju, N.K., 2022, Climatological wave height, wave period and wave power along coastal areas of the East Coast of the United States and Gulf of Mexico: data release DOI:10.5066/P9HJ0JIQ, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details: Downloaded dataset on 05/23/2023.
    Type_of_Source_Media: Digital
    Source_Contribution: point shapefile of wave power
    CMU_CT (source 2 of 2)
    Ackerman, K.V., Defne, Z., and Ganju, N.K., 2023, Conceptual marsh units of Connecticut salt marshes in Geospatial characterization of salt marshes in Connecticut: data release DOI:10.5066/P96QND48, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This dataset (Conceptual marsh units of Connecticut salt marshes) is within the larger data release (Geospatial characterization of salt marshes in Connecticut). 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 and areas of vegetation.
  2. How were the data generated, processed, and modified?
    Date: 2023 (process 1 of 4)
    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 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.
    a) Set the data frame coordinate system and projection to NAD 1983 UTM Zone 18N (2011).
    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_CT.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 18N (2011)) the feature dataset to obtain dissolved marsh units [mu_diss.shp]. 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:
    • CMU_CT
    Data sources produced in this process:
    • mu_diss.shp
    Date: 2023 (process 2 of 4)
    Create a raster surface dataset from the feature points, using inverse distance weighting (IDW). The parameters used in the IDW tool are conservative so that additional variability is not added to the wave power input dataset. IDW (Input point features: [WavePower.shp]; Output Cell Size=0.0001 degree; Power=2; Search Radius=Variable; Number of Points=1) to obtain [WavePower_CT_IDW.tif]. Data sources used in this process:
    • WavePower.shp
    Data sources produced in this process:
    • WavePower_CT_IDW.tif
    Date: 2023 (process 3 of 4)
    Clip the raster to marsh boundaries. A buffer zone is created around the marsh boundaries to facilitate alternative interpolation and clipping options in future studies.
    a) Create 300 m buffer around the marsh units polygons [mu_diss.shp] to create a clipping mask [mu_buff300m.shp]. BUFFER (Side type= Full; Method= Geodesic; Dissolve type= All).
    b) CLIP the raster [WavePower_CT_IDW.tif] with the clipping mask [mu_buff300m.shp] to obtain [WavePower_CT_IDW_clip.tif].
    c) EXTRACT BY MASK (Input raster= [WavePower_CT_IDW_clip.tif]; Mask=[mu_diss.shp]) to obtain [WavePower_IDW_MU.tif]. Data sources used in this process:
    • WavePower_CT_IDW.tif
    Data sources produced in this process:
    • WavePower_IDW_MU.tif
    Date: 2023 (process 4 of 4)
    Calculate mean wave power value for each marsh unit.
    a) PROJECT (Output coordinate system=GCS WGS 1984) [mu_diss.shp] to [mu_diss_WGS84].
    b) ZONAL STATISTICS AS TABLE (Feature Zone Data=[mu_diss_WGS84.shp]; zone field=FID_CMU; Value Raster=[WavePower_IDW_MU.tif]; Output Table=[wp]; Statistics type=MEAN).
    c) JOIN FIELD (Input table=[mu_diss_WGS84.shp]; Input join field=FID_CMU; Join Table=[wp]; Output join field=FID_CMU; Join Field= MEAN). Export dataset as a shapefile [mu_WavePower_CT.shp] and change “MEAN” to “WavePwr.”
    d) 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.
    e) 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 final mean tidal range dataset [mu_WavePower_CT.shp]. Data sources produced in this process:
    • mu_WavePower_CT.shp
  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?
    Marsh units, water and land boundaries inherit their horizontal accuracy from the accuracy of the source data, the conceptual marsh units, and their vertical accuracy from the elevation dataset (1-meter 2016 CT Lidar DEM). Wave power is calculated from a point grid derived from model simulations, then conservatively interpolated on a raster surface and averaged at each marsh unit. If a marsh unit does not overlap with any raster cell center, it is assigned the value of the raster cell with the largest overlap. There may be instances where seaward facing units are assigned a zero value due the grid spacing of the original dataset. The user is encouraged to refer to the original dataset (Aretxabaleta and others, 2022) to further investigate variations in wave power along the Connecticut coast.
  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 Connecticut'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 2172, 2402). In a few areas, there are no marsh units where there is visible marsh plain (e.g., northwest of marsh unit 1682), because the areas are classified in the NWI as estuarine intertidal unconsolidated shore, which is not included in our salt marsh boundaries. 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?
    Polygons do not overlap and wave power is positive. During processing of conceptual marsh units, 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?

Are there legal restrictions on access or use of the data?
Access_Constraints None
Use_Constraints The wave power 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_WavePower_CT.zip (ZIP file contains the shapefile mu_WavePower_CT.shp and the additional shapefile components), browse graphic (WavePower_CT_Browse.png), and FGDC CSDGM metadata in xml format.
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at 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. 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. 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. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The contents of this document do not necessarily reflect the views and policies of the Environmental Protection Agency. Not for navigational use.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 23-Oct-2023
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)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P96QND48/mu_WavePower_CT.faq.html>
Generated by mp version 2.9.51 on Mon Oct 23 17:02:49 2023