Sand Areas for the Undeveloped Areas of New Jersey's Barrier Islands, Extracted from Orthoimagery, March 9, 1991, to July 30, 2013

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Frequently anticipated questions:


What does this data set describe?

Title:
Sand Areas for the Undeveloped Areas of New Jersey's Barrier Islands, Extracted from Orthoimagery, March 9, 1991, to July 30, 2013
Abstract:
Assessing the physical change to shorelines and wetlands is critical in determining the resiliency of wetland systems that protect adjacent habitat and communities. The wetland and back-barrier shorelines of New Jersey changed as a result of wave action and storm surge that occurred during Hurricane Sandy, which made landfall on October 29, 2012. The impact of Hurricane Sandy will be assessed and placed in its historical context to understand the future vulnerability of wetland systems. Making these assessments will rely on data extracted from current and historical resources such as maps, aerial photographs, satellite imagery, and lidar elevation data, which document physical changes over time. This USGS Data Series publication includes several open-ocean shorelines, back-island shorelines, back-island shoreline points, sand area polygons, and sand lines for the undeveloped areas of New Jersey's barrier islands that were extracted from orthoimagery (ortho aerial photography) dated from March 9, 1991 to July 30, 2013. This data-set consists of polygons that represent the sand areas found in orthoimagery taken on the date specified in the filename and in the "Date_" field in the feature attribute table. Orthoimagery of New Jersey were acquired in digital format from U.S. Department of Agriculture (USDA), U.S. Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), and New Jersey Geographic Information Network (NJGIN). Prior to processing, the images were trimmed to remove the bulk of the areas that were not going to be analyzed. Using ERDAS Imagine 9.3, the images were classified into 40 classes that were coded as either sand or not sand. Due to varying conditions within the imagery, the coding occasionally varied from one area to another. Using ArcGIS 10.2, the resulting coded raster data-sets were converted to polygons and edited. The following list provides additional details about the orthoimagery used. The sand areas for each date and area is in a separate data-set (shapefile) named nj_sandpo_<range of dates>_<area name>.shp. The orthoimage date for each polygon is included in the shapefile attribute table's "Date_" field. Date Type Source Resolution 19910309-19910313 Pan USGS, DOQQ 1 m (meter) 19950325-19950407 CIR USGS, DOQQ 1 m 20020218-20020411 CIR NJGIN 1 m* 20060805-20060613 Natural USDA, NAIP 1 m 20070318-20070415 Natural NJGIN 1 m* 20080808-20080826 Natural USDA, NAIP 1 m 20100703-20100726 Natural USDA, NAIP 1 m 20120314-20120416 RGBI NJGIN 1 m* 20130707-20130730 Natural USDA, NAIP 1 m Pan - Panchromatic (1 band, gray scale) CIR - Color Infrared (infrared, red, green) Natural - Natural Color (red, green, blue) RGBI - Natural Color and Infrared (red, green, blue, and infrared) DOQQ - Digital Orthophoto Quarter Quads NAIP - National Agriculture Imagery Program *Resampled from 1-foot resolution imagery then smoothed using a 3 pixel by 3 pixel focal mean.
  1. How might this data set be cited?
    U.S. Geological Survey, 2015, Sand Areas for the Undeveloped Areas of New Jersey's Barrier Islands, Extracted from Orthoimagery, March 9, 1991, to July 30, 2013: U.S. Geological Survey Data Series 960, U.S. Geological Survey, St. Petersburg, Fla..

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -74.905370
    East_Bounding_Coordinate: -73.973050
    North_Bounding_Coordinate: 40.486412
    South_Bounding_Coordinate: 38.927798
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 09-Mar-1991
    Ending_Date: 30-Jul-2013
    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?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • GT-polygon composed of chains (6135)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -75.0
      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 North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 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?
    sandpo_*.shp
    Polygons representing sand areas extracted from orthoimagery. (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
    User specified identifier. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:6135
    Date_
    Date of orthoimage source. (Source: USGS) Date in month, day, year that the image was collected. This date may represent a date range if the exact date is unknown. If that is the case, the range of dates is stated in the Note attribute.
    YYYYMMDD
    Date of orthoimage source, formatted as an 8-digit number representing year, month, and day. (Source: USGS) Date formatted as an 8-digit number representing year, month, and day. This date may represent a date range if the exact date is unknown. If that is the case, the range of dates is stated in the Note attribute.
    Note
    Additional information. (Source: USGS) Additional text information. If the source orthoimage was taken within a range of dates, those dates are specified here.

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, Coastal and Marine Geology Program as a data source would be appreciated in products developed from these data, and such acknowledgment as 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. Users should be aware that comparisons with other data-sets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in photointerpretation, mapping conventions, and digital processes over time. These data are not legal documents and are not to be used as such.
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Kristy Guy
    600 4th St. S.
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    727-502-8181 (FAX)
    kguy@usgs.gov
    Hours_of_Service: Monday through Friday 9:00 AM to 5:00 PM (Eastern Time)

Why was the data set created?

These data were extracted from orthoimagery to document the changes to sand areas in the undeveloped areas of New Jersey's barrier islands due to Hurricane Sandy and over time from 1991 to 2013. These data will aid in developing an assessment of the physical change in wetlands due to wave action and storm surge from Hurricane Sandy and in determining the resiliency of wetland systems that protect adjacent habitat and communities.

How was the data set created?

  1. From what previous works were the data drawn?
    USGS Orthoimagery (source 1 of 4)
    USGS, 2015, USGS DOQQ Orthoimagery: USGS, http://earthexplorer.usgs.gov/.

    Type_of_Source_Media: online
    Source_Contribution: This data source was used to identify sand areas.
    USDA Orthoimagery (source 2 of 4)
    U.S. Department of Agriculture (USDA), 2015, USDA NAIP Orthoimagery: USDA, http://datagateway.nrcs.usda.gov/GDGOrder.aspx.

    Type_of_Source_Media: online
    Source_Contribution: This data source was used to identify sand areas.
    NJGIN Orthoimagery (source 3 of 4)
    New Jersey Geographic Information Network (NJGIN), 2015, NJGIN Orthoimagery: NJGIN, https://njgin.state.nj.us/NJ_NJGINExplorer/DataDownloads.jsp.

    Type_of_Source_Media: online
    Source_Contribution:
    This data source was used to hand-digitize a back-island shoreline.
    NOAA Orthoimagery (source 4 of 4)
    National Oceanic and Atmospheric Administration (NOAA), 2015, NOAA Orthoimagery: NOAA, http://storms.ngs.noaa.gov/storms/sandy/index.html.

    Type_of_Source_Media: online
    Source_Contribution:
    This data source was used to hand-digitize a back-island shoreline.
  2. How were the data generated, processed, and modified?
    Date: 2015 (process 1 of 2)
    Using ERDAS Imagine 9.3, the orthoimagery was trimmed to the study areas. Forty image classes were generated using the unsupervised classification method set to principal axis initializing, 1 standard deviation, 10 iterations maximum, 0.95 convergence threshold, skip factor of 1 for both x and y (no skipping), and zeroes not classified. The resulting classes were visually examined and coded as either sand or not sand. Using ArcGIS 10.2, the coded rasters were converted to sand area polygons. Polygons outside the island were deleted. Non-sand polygons within the main beach area with areas less than 25 square meters (m2) were merged with the sand area. Sand polygons with areas less than 100 m2 were deleted. The open-ocean shoreline edge of the polygons were trimmed and filled to a hand-digitized water line (the same-date open-ocean shoreline found within sshrln_*.shp, which is included in this Data Series publication) to simplify the irregular and misclassified areas caused by wet sand and waves. Person who carried out this activity:
    USGS
    600 4th St. S.
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    727-502-8181 (FAX)
    Hours_of_Service: Monday through Friday 8:00 AM to 5:00 PM (Eastern Time)
    Contact_Instructions:
    If unable to reach the contact by telephone, please leave a voice message.
    Data sources used in this process:
    • USGS Orthoimagery
    • USDA Orthoimagery
    • NJGIN Orthoimagery
    • NOAA Orthoimagery
    Data sources produced in this process:
    • sandpo_*.shp
    Date: 13-Oct-2020 (process 2 of 2)
    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?

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

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    The horizontal accuracy of the data is unknown.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    The October-November, 2012, imagery was not suitable for this type of analysis. Also, some areas in the Great Bay April 1, 2007, imagery were not suitable for this type of analysis so it includes only partial coverage. The March 11, 1991, imagery did not cover the entire Cape May study area.
  5. How consistent are the relationships among the observations, including topology?
    The coding of the unsupervised classes may have varied within a single image due to varying image quality and surface conditions (such as the color of the sand in overwash and scoured beach areas and in areas adjacent to inlets). Inconsistencies due to differences in image quality should be expected. Not all of the orthoimagery data-sets covered the entire study area. No adjustments were made for varying tide levels.

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:
None. However, variability in image quality from one date to another, from one image to another on the same date, and from one part of a single image to another part of the same image, exists due to many factors including variation in sun angle, atmospheric conditions, season, reflectivity of the earth surface, camera angle, camera lens, camera settings, film sensitivity, water turbidity, water depth, tide level, waves, and error in image rectification. No adjustments were made to account for tide level. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center, Coastal and Marine Geology Program as the originator of these data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    Kristy Guy
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, Fla.
    GIS/RS Analyst
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    Hours_of_Service: Monday-Friday, 9:00-5:00 Eastern Time
  2. What's the catalog number I need to order this data set? DS 928
  3. What legal disclaimers am I supposed to read?
    Although these data were processed successfully on a computer system at the USGS, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, firm, or product 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: 13-Oct-2020
Metadata author:
USGS
Attn: Kristy Guy
600 4th Street South
St. Petersburg, FL
USA

727-502-8000 (voice)
727-502-8181 (FAX)
kguy@usgs.gov
Hours_of_Service: Monday through Friday 9:00 AM to 5:00 PM (Eastern Time)
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/DS960_nj_sandpo.faq.html>
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