Impacts of Proposed Sediment Borrow Pits on the Nearshore Wave Climate and Longshore Transport Rate along Breton Island, LA: G4_Hh_Dd_wave_direction

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Frequently anticipated questions:


What does this data set describe?

Title:
Impacts of Proposed Sediment Borrow Pits on the Nearshore Wave Climate and Longshore Transport Rate along Breton Island, LA: G4_Hh_Dd_wave_direction
Abstract:
As part of a plan to preserve Breton Island, the southernmost extent of the Chandeleur Islands and part of the Breton Island National Wildlife Refuge, the National Fish and Wildlife Service (FWS) plans to nourish the island with sand supplied from offshore sand resources. The planned sand extraction sites are offshore of the island to the east and south in 5-10 m of water. Because borrow pits are perturbations to shallow-water bathymetry, they can impact the wave field in a variety of ways, and may result in alterations in sediment transport and new erosional or accretional patterns along the beach. For the present study, a scenario-based numerical modeling strategy was used to assess the impacts of the proposed borrow pits on the nearshore wave field. Impacts were assessed over a range of wave conditions, and were gauged by changes in significant wave height and wave direction inshore of the borrow sites.
Supplemental_Information:
This data layer is a subset of USGS Open-File Report 2015-1055, Impacts of Proposed Sediment Borrow Pits on the Nearshore Wave Climate and Longshore Transport Rate along Breton Island, LA. It is part of a set of data layers showing the spatial variability in mean wave direction for a range of offshore wave condition scenarios. Wave scenario dates correspond to active buoy dates and range between December 4, 1995 to December 30, 2013. For grid G4, there were three separate grids used in this project to consider changes in wave climate based on two potential sediment borrow pits. The data corresponding to G4_Hh_Dd contains results from grid G4 that has no pit present. Data corresponding to G4_P1_Hh_Dd contains results from grid G4 with the pit 1 configuration present. Data corresponding to G4_P2_Hh_Dd contains results from grid G4 with the pit 2 configuration present.
  1. How should this data set be cited?

    Dalyander, P. Soupy , Mickey, Rangley C. , Long, Joseph W. , and Flocks, James G. , 2015, Impacts of Proposed Sediment Borrow Pits on the Nearshore Wave Climate and Longshore Transport Rate along Breton Island, LA: G4_Hh_Dd_wave_direction: U.S. Geological Survey, Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

    This is part of the following larger work.

    Dalyander, P. Soupy , Mickey, Rangley C. , Long, Joseph W. , and Flocks, James G. , 2015, Impacts of Proposed Sediment Borrow Pits on the Nearshore Wave Climate and Longshore Transport Rate along Breton Island, LA: Open-File Report (OFR) 2015-1055, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -89.2322136333
    East_Bounding_Coordinate: -89.0421633798
    North_Bounding_Coordinate: 29.5224253171
    South_Bounding_Coordinate: 29.4216387757

  3. What does it look like?

    <http://pubs.usgs.gov/of/2015/1055/datadirectory/G4_bathymetry.jpg> (JPEG)
    Graphic showing the numerical model domain with the no pit configuration over which analysis was conducted.
    <http://pubs.usgs.gov/of/2014/xxxx/datadirectory/G4_P1_bathymetry.jpg> (JPEG)
    Graphic showing the numerical model domain with the pit 1 configuration over which analysis was conducted.
    <http://pubs.usgs.gov/of/2014/xxxx/datadirectory/G4_P2_bathymetry.jpg> (JPEG)
    Graphic showing the numerical model domain with the pit 2 configuration over which analysis was conducted.

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

    Beginning_Date: 04-Dec-1995
    Ending_Date: 30-Dec-2013
    Currentness_Reference: ground condition

  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?

      Indirect_Spatial_Reference: Gulf of Mexico
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-Polygon

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0197890536. Longitudes are given to the nearest 0.0226978275. Latitude and longitude values are specified in Decimal seconds.

      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.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.01 m
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates.

  7. How does the data set describe geographic features?

    G4_Hh_Dd_wave_direction
    Mean wave direction for specific wave scenarios. (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.

    Scenario_H
    Scenario wave height number (e.g. "h" in Hh_Dd, see wave_scenarios.txt) (Source: USGS)

    Range of values
    Minimum:1
    Maximum:8
    Units:non-dimensional
    Resolution:1

    Scenario_D
    Scenario wave direction number (e.g. "d" in Hh_Dd, see wave_scenarios.txt) (Source: USGS)

    Range of values
    Minimum:1
    Maximum:16
    Units:non-dimensional
    Resolution:1

    WaveDirection
    mean wave direction (Source: USGS)

    Range of values
    Minimum:0
    Maximum:360
    Units:degrees
    Resolution:0.01

    Entity_and_Attribute_Overview:
    The entity and attribute information provided here describes the tabular data associated with the dataset. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the dataset.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information was generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    U.S. Geological Survey

  3. To whom should users address questions about the data?

    U.S. Geological Survey, USGS Southeast Area
    Attn: P. Soupy Dalyander
    Research Oceanographer
    600 4th Street South
    St. Petersburg, FL 33701
    US

    727-502-8124 (voice)
    727-502-8001 (FAX)
    sdalyander@usgs.gov


Why was the data set created?

This GIS layer contains an estimate of mean wave direction in the shallow northern Gulf of Mexico for a single set of wave conditions. This output is based on a numerical model output of wave patterns for a given wave height scenario, corresponding to a particular set collected during 1995-2013 of offshore wave conditions at National Oceanic and Atmospheric Administration (NOAA) National Data Buoy Center (NDBC) buoy 42040. The specific wave conditions for a given layer are indicated by the file name (of format Hh_Dd_wave_direction), in the shapefile attributes, and may be found by comparing the scenario name (Hh_Dd) to the look-up table (wave_scenarios.txt) included in the GIS zip file located at <http://pubs.usgs.gov/of/2014/xxxx/datafiles.html> (G4_H1_D1_wave_direction.zip). Shapefile attributes for the other G4 grids with pit 1 and 2 present can be found at <http://pubs.usgs.gov/of/2014/xxxx/datafiles.html> (G4_P1_H1_D1_wave_direction.zip) and <http://pubs.usgs.gov/of/2014/xxxx/datafiles.html> (G4_P2_H1_D1_wave_direction.zip). This data layer is intended to illustrate the spatial variability in mean wave direction for this particular offshore wave climate scenario.


How was the data set created?

  1. From what previous works were the data drawn?

    NOAA GFS (source 1 of 1)
    NOAA National Centers for Environmental Predictions (NCEP), 201405, NOAA/NCEP Global Forecast System (GFS) Atmospheric Model: NOAA National Centers for Environmental Prediction, Camp Springs, MD.

    Online Links:

    Type_of_Source_Media: Digital and/or Hardcopy Resources
    Source_Contribution:
    Wind speed data at 10 m above the sea surface from the NOAA Global Forecast System (GFS) 0.5 degree model is interpolated by NOAA to the 4' Wavewatch III grid and archived. These archived data are used to drive the numerical wave and circulation model that creates estimates of bottom shear stress.

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

    Date: 22-May-2014 (process 1 of 2)
    The Simulation WAves Nearshore (SWAN) model (v.41.01) was used to estimate the spectral wave field for the offshore wave conditions corresponding to this scenario Hh_Dd (characteristics of which may be found in the included wave_scenarios.txt file) in each grid cell in the model domain. SWAN is a 3rd generation phase-averaged numerical wave model, which conserves wave energy subject to generation, dissipation, and transformation processes and resolves spectral energy density over a range of user-specified frequencies and directions. Model bathymetry was provided by the NOAA National Geophysical Data Center Northern Gulf Coast digital elevation map, referenced to NAVD88. Significant wave height, dominant wave period, and mean wave direction were prescribed as SWAN TPAR format files every 5 grid cells along the model boundary using results from the NOAA Wavewatch III 4' multi-grid model for a representative moment in time corresponding to the offshore wave conditions of the scenario, and the specific time, which may be found in the included wave_scenarios.txt file. A JONSWAP (JOint NOrth Sea WAve Project) spectral shape was assumed at these boundary points. Wind forcing was provided using the archived Wavewatch III 4' winds, extracted from the NOAA GFS wind model, for this time. The SWAN directional space covers a full circle with a resolution of 6 degrees (60 bins). The frequency range was specified as 0.05 - 1 Hz with logarithmic spacing. Bottom friction calculations used the JONSWAP formulation with a uniform roughness coefficient of 0.067 m^2/s^3. 3rd-generation physics are activated, which accounts for wind wave generation and white capping (via the Komen et al parameterization). The model system outputs the mean wave direction values included in this layer.

    Date: 22-May-2014 (process 2 of 2)
    Exported the mean wave direction values for each grid cell from MATLAB format into an ArcGIS polygon shapefile using the Mathworks MATLAB Mapping Toolbox (v2014A). The shapefile was written with the "shapewrite" command via MATLAB; but because MATLAB does not assign a projection during export, projections associated with the bathymetry used in the numerical models were later added in ArcCatalog 10.2. The file was then quality checked in ArcMap to ensure values were properly exported to the shapefile from MATLAB.

  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?

    The WaveDirect attribute in this data layer corresponds to mean wave direction for Hh_Dd, characteristics of which may be found in the included wave_scenarios.txt file. Values will vary if a different numerical model is used to estimate the waves.

  2. How accurate are the geographic locations?

    Numerical models are used in estimating the mean wave direction values for this data layer. Because the overall horizontal accuracy of the dataset depends on the accuracy of the model, the underlying bathymetry, forcing values used, and so forth, the spatial accuracy of this data layer cannot be meaningfully quantified.

  3. How accurate are the heights or depths?

    Vertical datum is North American Vertical Datum of 1988 (NAVD88) with an estimated resolution of 0.01 m.

  4. Where are the gaps in the data? What is missing?

    Mean wave direction was calculated at all locations (wet grid cells) where model output exists. Because of differences between the scenarios, not all grid cells may be included in all scenarios. The mean wave direction was calculated for a particular scenario (Hh_Dd), the characteristics of which may be found in the included wave_scenarios.txt file. The mean wave direction was calculated from wave estimates generated with NOAA's Wavewatch III and Delft University of Technology's Simulating WAves Nearshore (SWAN) software and would vary if a different model were used or if different model inputs (such as bathymetry, forcing winds, and boundary conditions) or parameterizations were chosen.

  5. How consistent are the relationships among the observations, including topology?

    No duplicate features are present. All polygons are closed, and all lines intersect where intended. No undershoots (lines falling short of the line they should intersect to form the polygon) or overshoots (lines crossing over the line they should intersect to form the polygon) are present.


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:
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 originator of the dataset.

  1. Who distributes the data set? (Distributor 1 of 1)

    U.S. Geological Survey, USGS Southeast Area
    Attn: P. Soupy Dalyander
    Research Oceanographer
    600 4th Street South
    St. Petersburg, FL 33701
    US

    727-502-8124 (voice)
    727-502-8001 (FAX)
    sdalyander@usgs.gov

  2. What's the catalog number I need to order this data set?

  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.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 27-May-2014
Metadata author:
P. Soupy Dalyander
U.S. Geological Survey, USGS Southeast Area
Research Oceanographer
600 4th Street South
St. Petersburg, FL 33701
US

727-502-8124 (voice)
727-502-8001 (FAX)
sdalyander@usgs.gov

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


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