Baseline_BackBarrier.shp - Baseline Along the Back-Barrier (North-Facing) Coast of Dauphin Island, Alabama, Generated to Calculate Shoreline Change Rates.

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Frequently anticipated questions:

What does this data set describe?

Title:
Baseline_BackBarrier.shp - Baseline Along the Back-Barrier (North-Facing) Coast of Dauphin Island, Alabama, Generated to Calculate Shoreline Change Rates.
Abstract:
Analysis of shoreline change for Dauphin Island, Alabama was conducted using the U.S. Geological Survey (USGS) Digital Shoreline Analysis System (DSAS) v.4.3 for ArcMap (Thieler and others, 2009) and vector shorelines derived from air photos and lidar elevation surveys. DSAS-generated transects were cast at 100-meter intervals along a user defined shore-parallel baseline. The intersections of transects with the mean high water (MHW) shoreline positions are identified by intercept points. The rate of shoreline change was determined by measuring the differences in the distance to each historical shoreline position from the baseline along each transect.
Three analyses of change rates were conducted using a combination of shorelines derived from different data sources. Shoreline change rates from the wet dry line (WDL) shoreline were derived from 10 sets of air photos from 1940 - 2015. Rates of change were also calculated using MHW shorelines extracted from 14 lidar datasets from 1998 - 2014. A final change analysis was conducted using a combination of all WDL (aerial) and MHW (lidar) shorelines, from 1940 - 2015.
  1. How might this data set be cited?
    U.S. Geological Survey, 20170616, Baseline_BackBarrier.shp - Baseline Along the Back-Barrier (North-Facing) Coast of Dauphin Island, Alabama, Generated to Calculate Shoreline Change Rates.: U.S. Geological Survey Data Release doi:10.5066/F7T43RB5, U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -88.343474
    East_Bounding_Coordinate: -88.097933
    North_Bounding_Coordinate: 30.283590
    South_Bounding_Coordinate: 30.236274
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 16-Jun-2017
    Currentness_Reference:
    Publication date
  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?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • String (2)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 16
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -87.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      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_North_American_1983.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    Baseline_BackBarrier.shp
    Reference baseline used by the Digital Shoreline Analysis System (DSAS) to calculate rate-of-change statistics. (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.
    ID
    Field required by the Digital Shoreline Analysis System (DSAS) software. DSAS uses this value to determine the ordering sequence of transects when the baseline feature contains multiple segments. Individual segments are numbered sequentially alongshore. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:2
    Shape_Leng
    System-generated attribute field, which was automatically created by ArcGIS to indicate the feature length. (Source: Esri)
    Range of values
    Minimum:12239.8952035
    Maximum:20127.9559614
    Units:Meters

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
    Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, as a data source would be appreciated in products developed from these data, and such acknowledgment is standard for citation and legal practices. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff.
  3. To whom should users address questions about the data?
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida
    Attn: Rachel E. Henderson
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)-502-8000 (voice)
    rehenderson@usgs.gov

Why was the data set created?

This dataset includes a reference baseline to be used with the DSAS to calculate shoreline change statistics for the back-barrier (north-facing) coast of Dauphin Island, Alabama. This baseline shapefile serves as the starting point for transects cast by the DSAS application. The transects are cast perpendicular to the baseline, and parallel to the general shoreline trend, and intersect each shoreline to establish measurement points, which are used to generate rates of shoreline change. Rates of shoreline change were generated in ArcGIS version 10.0 using the DSAS, version 4.3 (Theiler and other, 2009).

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 01-Aug-2016 (process 1 of 3)
    A feature class was created in a personal geodatabase and was used to construct a baseline offshore from the time series of shoreline positions using standard editing tools in ArcMap v10.0. The baseline was positioned to conform to changes in the combined alongshore orientation of historical (MHW [lidar]and WDL [aerial]) shorelines. This was done so the transects, which are generated by the Digital Shoreline Analysis System v4.3 from the baseline, would intersect perpendicular to the general trend of the shorelines. The baseline feature was constructed along the back-barrier (north-facing) coast of the island, to capture change to this sandy shoreline, as well as the distinct marsh shorelines of the eastern end of Dauphin Island. Person who carried out this activity:
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida
    Attn: Rachel E. Henderson
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)-502-8000 (voice)
    rehenderson@usgs.gov
    Data sources produced in this process:
    • DI_backbarrier_baseline
    Date: 01-Mar-2017 (process 2 of 3)
    The baseline feature class was exported from a personal geodatabase to a shapefile in ArcCatalog (v.10.0) by performing a right-mouse click on the data layer > export > to shapefile (single). Person who carried out this activity:
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida
    Attn: Rachel E. Henderson
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)-502-8000 (voice)
    rehenderson@usgs.gov
    Data sources used in this process:
    • DI_backbarrier_baseline
    Data sources produced in this process:
    • Baseline_BackBarrier.shp
    Date: 13-Oct-2020 (process 3 of 3)
    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?
    Thieler, E.R., Himmelstoss, E.A., Zichichi, J.L., and Ergul, A., 2009, Digital Shoreline Analysis System (DSAS) version 4.0 - An ArcGIS extension for calculating shoreline change: U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Other_Citation_Details: Current version of software at time of use was 4.3

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

  1. How well have the observations been checked?
    The attribute, "ID", in this layer is based on the requirements for use within the Digital Shoreline Analysis System (DSAS) software (USGS Open-File Report 2008-1278). The data have been quality checked.
  2. How accurate are the geographic locations?
    The baseline serves as a reference point for transects cast by the Digital Shoreline Analysis System (DSAS) software. It does not correspond to any real-world feature.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This baseline file is complete and contains one baseline segment used to cast transects along the back-barrier (north-facing) coast of Dauphin Island, alabama, where lidar shoreline position data were available and additional shoreline data are present to calculate either a short- or long-term rate of change.
  5. How consistent are the relationships among the observations, including topology?
    This multipart polyline file has identification attributes (ID) of 1 and 2. This field is used by the Digital Shoreline Analysis System (DSAS) to designate the alongshore order of baselines if there are more than one.

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 in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    600 4th Street South
    St. Petersburg, Florida
    US

    (727)-502-8000 (voice)
    rehenderson@usgs.gov
  2. What's the catalog number I need to order this data set? Baseline_BackBarrier.shp
  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?
    This zip file contains data available in Environmental Systems Research Institute (Esri) polyline 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: 13-Oct-2020
Metadata author:
U.S. Geological Survey
Attn: Rachel Henderson
600 4th Street South
St. Petersburg, Florida
US

(727)-502-8000 (voice)
rehenderson@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/Baseline_BackBarrier_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:33 2021