Hydrodynamic and Sediment Transport Model Application for OSAT3 Guidance: Surf-zone integrated alongshore potential flux for oil-sand balls of varying sizes weighted by probability of wave scenario occurrence

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Frequently-anticipated questions:

What does this data set describe?

Title:
Hydrodynamic and Sediment Transport Model Application for OSAT3 Guidance: Surf-zone integrated alongshore potential flux for oil-sand balls of varying sizes weighted by probability of wave scenario occurrence
Abstract:
The U.S. Geological Survey has developed a method for estimating the mobility and potential alongshore transport of heavier-than-water sand and oil agglomerates (tarballs or surface residual balls, SRBs). During the Deepwater Horizon spill, some oil that reached the surf zone of the northern Gulf of Mexico mixed with suspended sediment and sank to form sub-tidal mats. If not removed, these mats can break apart to form SRBs and subsequently re-oil the beach. A method was developed for estimating SRB mobilization and alongshore movement. A representative suite of wave conditions was identified from buoy data for April, 2010, until August, 2012, and used to drive a numerical model of the spatially-variant alongshore currents. Potential mobilization of SRBs was estimated by comparing combined wave- and current-induced shear stress from the model to critical stress values for several sized SRBs. Potential alongshore flux of SRBs was also estimated to identify regions more or less likely to have SRBs deposited under each scenario. This methodology was developed to explain SRB movement and redistribution in the alongshore, interpret observed re-oiling events, and thus inform re-oiling mitigation efforts.
Supplemental_Information:
This data layer is a subset of USGS Open-File Report 2012-1234, Hydrodynamic and Sediment Transport Model Application for OSAT3 Guidance. It is a weighted average of surf-zone integrated alongshore potential flux for various size SRBs based on probability of occurrence during the period of 04/01/2010 to 08/01/2012 for a range of wave climate scenarios. The results for each individual scenario that form the basis of this weighted averaged may be found within the report, naming convention Hh_Dd_potential_flux, where Hh_Dd indicates the specific scenario (see wave_scenarios.txt). SRB class properties may be found in the look-up table included in the GIS zip file, SRB_casses.txt.
  1. How should this data set be cited?

    Dalyander, P. Soupy , Long, Joseph W. , Plant, Nathaniel G. , and Thompson, David, 2012, Hydrodynamic and Sediment Transport Model Application for OSAT3 Guidance: Surf-zone integrated alongshore potential flux for oil-sand balls of varying sizes weighted by probability of wave scenario occurrence: Open-File Report (OFR) 2012-1234, 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.

    Plant, Nathaniel G. , Long, Joseph W. , Dalyander, P.Soupy, and Thompson, David, 2012, Hydrodynamic and Sediment Transport Model Application for OSAT3 Guidance: Open-File Report (OFR) 2012-1234, U.S. Geological Survey, Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -88.712143
    East_Bounding_Coordinate: -85.506075
    North_Bounding_Coordinate: 30.396484
    South_Bounding_Coordinate: 29.970005

  3. What does it look like?

    model_bathymetry.jpg (JPEG)
    Graphic showing the numerical model domain over which analysis is conducted.

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

    Beginning_Date: 01-Apr-2010
    Ending_Date: 01-Aug-2012
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: vector digital data

  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):
      • Entity point (993)

    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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

      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?

    Weighted_potential_flux
    Surf-zone integrated alongshore potential flux for oil-sand balls of varying sizes weighted by probability of wave scenario occurrence (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.

    SRB1_high
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 1 (see SRB_classes.txt) calculated from the Shield's parameter. The Shield's parameter is a relative high critical stress estimate and does not account for a reduced critical stress due to potential SRB exposure above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB1_med
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 1 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.02. This critical stress estimate is a mid-range value accounting for a reduced critical stress due to some exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB1_low
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 1 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.01. This critical stress estimate is a low value accounting for a reduced critical stress due to exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB2_high
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 2 (see SRB_classes.txt) calculated from the Shield's parameter. The Shield's parameter is a relative high critical stress estimate and does not account for a reduced critical stress due to potential SRB exposure above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB2_med
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 2 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.02. This critical stress estimate is a mid-range value accounting for a reduced critical stress due to some exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB2_low
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 2 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.01. This critical stress estimate is a low value accounting for a reduced critical stress due to exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB3_high
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 3 (see SRB_classes.txt) calculated from the Shield's parameter. The Shield's parameter is a relative high critical stress estimate and does not account for a reduced critical stress due to potential SRB exposure above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB3_med
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 3 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.02. This critical stress estimate is a mid-range value accounting for a reduced critical stress due to some exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB3_low
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 3 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.01. This critical stress estimate is a low value accounting for a reduced critical stress due to exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB4_high
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 4 (see SRB_classes.txt) calculated from the Shield's parameter. The Shield's parameter is a relative high critical stress estimate and does not account for a reduced critical stress due to potential SRB exposure above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB4_med
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 4 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.02. This critical stress estimate is a mid-range value accounting for a reduced critical stress due to some exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB4_low
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 4 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.01. This critical stress estimate is a low value accounting for a reduced critical stress due to exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB5_high
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 5 (see SRB_classes.txt) calculated from the Shield's parameter. The Shield's parameter is a relative high critical stress estimate and does not account for a reduced critical stress due to potential SRB exposure above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB5_med
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 5 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.02. This critical stress estimate is a mid-range value accounting for a reduced critical stress due to some exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB5_low
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 5 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.01. This critical stress estimate is a low value accounting for a reduced critical stress due to exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB6_high
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 6 (see SRB_classes.txt) calculated from the Shield's parameter. The Shield's parameter is a relative high critical stress estimate and does not account for a reduced critical stress due to potential SRB exposure above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB6_med
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 6 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.02. This critical stress estimate is a mid-range value accounting for a reduced critical stress due to some exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

    SRB6_low
    Surf-zone integrated alongshore potential flux (in kg/s) as an average weighted by percent occurrence in the time period of 04/01/2010 to 08/01/2012 of surf-zone integrated alongshore potential flux for 80 wave scenarios (see wave_scenarios.txt) using a critical stress for SRB class 6 (see SRB_classes.txt) calculated from a non-dimensional Shield's parameter of 0.01. This critical stress estimate is a low value accounting for a reduced critical stress due to exposure of the SRB above the seafloor. (Source: USGS)

    Range of values
    Minimum:-1000
    Maximum:1000
    Units:kg/s
    Resolution:0.000001

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?

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

    P. Soupy Dalyander
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA 02543-1598
    USA

    (508) 548-8700 x2290 (voice)
    (508) 457-2310 (FAX)
    sdalyander@usgs.gov

Why was the data set created?

This GIS layer contains an estimate of the average surf-zone integrated alongshore potential flux (in kg/s) of various size surface residual balls (SRBs) in the shallow northern Gulf of Mexico (Alabama and portion of the Florida coast) for the time period of 04/01/2010 to 08/01/2012. This output is based on numerical model output of wave and circulation patterns for a set of 80 wave height scenarios, each corresponding to a particular set of offshore wave conditions at NOAA NDBC buoy 42040. The wave and wind conditions at the buoy each hour over the time period of interest have been identified as most closely corresponding to 1 of these 80 conditions, and a probability of occurrence assigned to each scenario based on the percentage of observations assigned to that scenario (see included wave_scenarios.txt). This layer contains the weighted average of the surf-zone integrated alongshore potential flux (smoothed over 2 km to reduce model noise) for each of those scenarios. This value is an estimate of the total alongshore flux in the surf zone at each alongshore location, assuming the entire seafloor was covered with SRBs of the given size and density. Because the seafloor is not covered in SRBs, this potential flux identifies patterns in transport and does quantify the actual flux at any given location or time. Characteristics of SRB classes may be found in the look-up table included in the GIS zip file, SRB_casses.txt. This data layer is intended to show patterns in transport (convergences, divergences, and gradients) for intended use by individuals in SRB mitigation attempting to explain redistribution of SRBs over this time period.

How was the data set created?

  1. From what previous works were the data drawn?

    NOAA GFS (source 1 of 3)
    NOAA National Centers for Environmental Prediction (NCEP), 20110601, NOAA/NCEP Global Forecast System (GFS) Atmospheric Model: NOAA National Centers for Environmental Prediction, Camp Springs, MD.

    Online Links:

    Type_of_Source_Media: online
    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' Wavewatch3 grid and archived. These archived data are used to drive the numerical wave and circulation model that creates estimated of bottom shear stress.

    NOAA WW3 (source 2 of 3)
    NOAA National Centers for Environmental Prediction (NCEP, 20121001, NOAA/NWS/NCEP 4' Wavewatch III Operational Wave Forecast: NOAA National Centers for Environmental Prediction, Camp Springs, MD.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    Boundary conditions for the wave model were provided by the 4' NOAA/NWS/NCEP Wavewatch III operational ocean wave forecast.

    NDBC42040 (source 3 of 3)
    National Data Buoy Center, 20120901, National Data Buoy Center Buoy 42040: National Oceanic and Atmospheric Administration, Stennis Space Center, MS.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution:
    Observational wave data from NDBC Buoy 42040 were used to identify the percentage of observations between 04/01/2010 and 08/01/2012 which corresponded to each of 80 wave scenarios distinguished by wave height and direction, and to identify a characteristic time period in the record for each scenario.

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

    Date: 2012 (process 1 of 7)
    Using observed wave conditions from NOAA buoy 42040 and Mathworks MATLAB software 2012A, the hourly wave buoy observations between 04/01/2010 and 08/01/2012 were each classified as falling into 1 of 80 wave scenarios defined by wave height and direction. For each scenario, a specific time step was identified in the record which was most representative of the other observations within the same wave height and direction bins based on both wave (height, period, and direction) and wind (speed and direction) characteristics. The characteristics of these scenarios, along with the percentage of observation in the record and the chosen representative time period, may be found in wave_scenarios.txt. The probability of occurrence for each wave scenario along with its characteristics and representative time periods were saved in MATLAB .mat format.

    Person who carried out this activity:

    Nathaniel Plant
    USGS
    Oceanographer
    600 4th Street S
    St. Petersburg, FL 33701

    (727) 803-8747 x3072 (voice)
    (727) 803-2023 (FAX)
    nplant@usgs.gov

    Data sources used in this process:
    • NDBC42040

    Data sources produced in this process:

    • WAVE_SCENARIOS

    Date: 2012 (process 2 of 7)
    The D-Flow and D-Waves components of the Deltares Delft3D numerical model suite (version 4.00.01) were used to estimate bottom orbital velocity, peak period, peak wave direction, and east and north components of wind and wave-driven velocity for the offshore wave conditions corresponding to each scenario's representative time period (characteristics of which may be found in the included wave_scenarios.txt file) in each grid cell in the model domain. The wave model D-Waves, based on the Simulating WAves Nearshore (SWAN) model, 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. D-Wave was used in stationary mode. D-Flow solves the shallow water Navier Stokes equations and is run in 2-D depth-averaged mode, with linkage to D-Waves allowing the generation of wave-driven currents via wave radiation stress forcing. Default values for model parameters governing horizontal viscosity, bottom roughness, and wind drag were used. Neumann boundary conditions were used along the east, west, and south model boundaries with harmonic forcing set to zero. 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 wave direction were prescribed as D-Wave TPAR format files every 30 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, the specific time of 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 WavewatchIII 4' winds, extracted from the NOAA GFS wind model, for this time. The D-Wave directional space covers a full circle with a resolution was 5 degrees (72 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 m2/s3. 3rd-generation physics are activated which accounts for wind wave generation, triad wave interactions and whitecapping (via the Komen et al parameterization). Depth-induced wave breaking dissipation is included using the method of Battjes and Janssen with default values for alpha (1) and gamma (0.73). Wave model outputs of bottom orbital velocity, peak period, and peak wave direction were extracted on the wave model grid, and current model outputs of east and north current velocity component were extracted and interpolated to the wave model grid (staggered points in relation to the current model grid).

    NDBC observations from station 42012 for the representative scenario time periods were used to validate the wave model results.

    Person who carried out this activity:

    Joseph W. Long
    U.S. Geological Survey
    Oceanographer
    600 4th Street S
    St. Petersburg, FL 33701
    USA

    (727) 803-8747 x3024 (voice)
    (727) 803-2032 (FAX)
    jwlong@usgs.gov

    Data sources used in this process:
    • NOAA GFS
    • NOAA WW3
    • WAVE_SCENARIOS

    Data sources produced in this process:

    • DELFT3D

    Date: 2012 (process 3 of 7)
    Identify the spatial extent of the surf zone at each alongshore location using Mathworks MATLAB software (v2012A). The shoreline is identified from the gridded bathymetry as the cross-shore grid cell of minimum water depth at each alongshore transect. In areas where lagoons separate barrier islands and the mainland coast, the shoreline is considered along the seaward side of the barrier island only. The shoreline is not continuous due to interruptions at inlets. For each alongshore transect, the surf zone is defined as the area between the shoreline and the location of maximum wave height (found in a search area extending from the shoreline to the most offshore point of modeled depth-induced wave breaking dissipation). The extent of the surf zone (as indices into the grid at each alongshore location of the cross-shore position of the shoreline and seaward edge of the surf zone) was saved for all of the scenarios into a MATLAB .mat structure.

    Person who carried out this activity:

    David Thompson
    U.S. Geological Survey
    Oceanographer
    600 4th Street S
    St. Petersburg, FL 33701
    USA

    (727) 803-8747 x3079 (voice)
    (727) 803-2032 (FAX)
    dthompson@usgs.gov

    Data sources used in this process:
    • DELFT3D

    Data sources produced in this process:

    • SURFZONE

    Date: 2012 (process 4 of 7)
    For each scenario, estimate the spatially variant potential flux for each SRB size class, characteristics of which may be found in the included SRB_classes.txt file. Calculations are performed in Mathworks MATLAB (v2012A). Potential flux is calculated for model output values (wave orbital velocity, peak period, and direction; depth-averaged current magnitude and direction; total water level from the model and bathymetry) using the Shield's parameter following the Soulsby-van Rijn approach described in Soulsby (1997). The direction of transport is identified is either positive (to the east) or negative (to the west) from the sign of the alongshore component of velocity (output u1 from the numerical model). The Shield's parameter is identified as a "high" critical stress value, corresponding to instances when an SRB of the identified size is within a uniform bed of similarly sized SRBs. Exposure above the bed, such as may occur with a single SRB on a sand band, reduces the critical shear stress value for incipient motion. Based on field observations of gravel and sand mixtures, a "medium" critical stress value is calculated from a constant non-dimensional Shields parameter of 0.02, and a "low" critical stress value is calculated from a constant non-dimensional Shields parameter of 0.01 (Andrews, 1983; Bottacin-Busolin et al, 2008; Fenton and Abbott, 1977; Wiberg and Smith, 1987; Wilcock, 1998). Each of these three threshold values are saved in MATLAB .mat format.

    The same individual who completed this processing step completed all additional processing steps. References:

    Andrews, E.D. (1983). Entrainment of gravel from naturally sorted riverbed material. Geo. Soc. Amer. Bull. (94), 1225-1231. Bottacin-Busolin, A., Tait, S.J., Marion, A., Chegini, A., Tregnaghi, M. (2008). Probabilistic description of grain resistance from simultaneous flow field and grain motion measurements. Water Resources Res. (44), WO9419. Fenton, J.D., Abbott, J.E. (1977). Initial movement of grains on a stream bed: the effect of relative protusion. Proc. R. Soc. Lond. A. (352), 523-537. Soulsby, R., 1997. Dynamics of Marine Sands, a Manual for Practical Applications. Thomas Telford Publications, London. Wibert, P.L., Smith, J.D. (1987). Calculations of the Critical Shear Stress for Motion of Uniform and Heterogenous Sediments. Water Resources Res. (23), 1471-1480. Wilcock, P.R. (1998). Two-Fraction Model of Initial Sediment Motion in Gravel-Bed Rivers. Science (280), 410-412.

    Person who carried out this activity:

    P. Soupy Dalyander
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA 02543

    (508) 548-8700 x2290 (voice)
    (508) 457-2310 (FAX)
    sdalyander@usgs.gov

    Data sources used in this process:
    • DELFT3D

    Data sources produced in this process:

    • FLUX2D

    Date: 2012 (process 5 of 7)
    For each scenario, integrate the alongshore potential flux at each alongshore location over the cross-shore region identified as surf zone in the previous processing step for this scenario. The 2D potential flux (in m3/m/s) is multiplied times the cross-shore width of each grid cell (in m, corresponding to half the distance from each grid cell to the grid cell to the north plus half the distance from the grid cell to the grid cell to the south) to obtain the flux (in m3/s) at that grid cell. This value is then summed over all of the cross-shore locations at that alongshore location and multiplied by SRB density (2107 kg/m3) to obtain the surf-zone integrated alongshore potential flux (in kg/s) at each alongshore location. The surf-zone integrated alongshore potential flux is then smoothed with a 2-km Hanning window filter to remove small-scale structure likely associated with model noise. These values are saved in Matlab .mat format.

    Data sources used in this process:

    • FLUX2D
    • SURFZONE

    Data sources produced in this process:

    • FLUX1D

    Date: 2012 (process 6 of 7)
    For each grid cell, calculate the average surf-zone integrated alongshore potential flux from the surf-zone integrated alongshore potential flux for each scenario, weighted by the percent observation of that scenario in the time period of 04/01/2010 to 08/01/2012 (see wave_scenarios.txt).

    Data sources used in this process:

    • WAVE_SCENARIOS
    • FLUX1D

    Data sources produced in this process:

    • AVG_FLUX

    Date: 2012 (process 7 of 7)
    Exported the values for each alongshore point from MATLAB format into an ArcGIS shapefile using the Mathworks MATLAB Mapping Toolbox (v2012A). The shapefile is written with the "shapewrite" command. Because MATLAB does not assign a projection, the projection corresponding to the projection associated with the bathymetry used in the numerical models is added in ArcCatalog 9.3. The file was then quality checked in ArcMap to insure values were properly exported to the shapefile from MATLAB.

    Data sources used in this process:

    • AVG_FLUX

  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 attributes in this data layer correspond to an average of surf-zone integrated alongshore potential flux for 80 individual representative wave scenarios, weighted by probability of occurrence over the time period of 04/01/2010 to 08/01/2012, for various classes of SRBs, the characteristics of which may be found in the included SRB_classes.txt file. The potential flux was calculated from wave and current estimates generated with Delft3D, and would vary if different models were used or if different model inputs (such as bathymetry, forcing winds, and boundary conditions) or parameterizations were chosen. Potential flux estimates would vary for different size or density SRBs and/or if a different formulation for calculating the flux is used. Potential flux estimates would also vary if a different set of wave scenarios (see wave_scenarios.txt) were used to represent the time frame of interest, or if a different time period of interest was examined. The quantitative value calculated assumes the entire seafloor is covered with SRBs of the given size and density; since this is not the case, the output provides patterns in transport for use in identifying likely areas of deposition and is not quantitatively meaningful in terms of actual flux at any point in time or space.

  2. How accurate are the geographic locations?

    Numerical models are used in the generation of hydrodynamic conditions used in creating this data layer. Because the overall horizontal accuracy of the data set 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?

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

    All model output values were used in the calculation of this statistic. The statistic was calculated as an average of surf-zone integrated alongshore potential flux for 80 individual representative wave scenarios, weighted by probability of occurrence over the time period of 04/01/2010 to 08/01/2012, for various classes of SRBs, the characteristics of which may be found in the included SRB_classes.txt file. The potential flux was calculated from wave and current estimates generated with Delft3D, and would vary if different models were used or if different model inputs (such as bathymetry, forcing winds, and boundary conditions) or parameterizations were chosen. Potential flux estimates would vary for different size or density SRBs and/or if a different formulation for calculating flux is used. Potential flux estimates would also vary if a different set of wave scenarios (see wave_scenarios.txt) were used to represent the time frame of interest, or if a different time period of interest was examined.

  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 or overshoots 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)

    P. Soupy Dalyander
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA 02543-1598
    USA

    (508) 548-8700 x2290 (voice)
    (508) 457-2310 (FAX)
    sdalyander@usgs.gov

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

    Weighted_potential_flux.shp: average surf-zone integrated alognshore potential flux for various size SRBs (see SRB_classes.txt) for the time period of 04/01/2010 to 08/01/2012.

  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?

  5. What hardware or software do I need in order to use the data set?

    These data are available in Environmental Systems Research Institute (ESRI) shapefile format. The user must have ArcGIS or ArcView 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing the data. A free data viewer, ArcExplorer, capable of displaying the data is available from ESRI at www.esri.com.

Who wrote the metadata?

Dates:
Last modified: 12-Nov-2012
Metadata author:
U.S. Geological Survey
c/o P. Soupy Dalyander
Oceanographer
384 Woods Hole Role
Woods Hole, MA 02543-1598
USA

(508) 548-8700 x2290 (voice)
(508) 457-2310 (FAX)
sdalyander@usgs.gov

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

Generated by mp version 2.8.25 on Mon Nov 12 10:39:14 2012