Vectorized Shoreline of Alabama Derived from 1978-1981 Source Data

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

Title:

Vectorized Shoreline of Alabama Derived from 1978-1981 Source Data

Abstract:

There are critical needs for a nationwide compilation of reliable shoreline data. To meet these needs, the USGS has produced a comprehensive database of digital vector shorelines by compiling shoreline positions from pre-existing historical shoreline databases and by generating historical and modern shoreline data. Shorelines are compiled by state and generally correspond to one of four time periods: 1800s, 1920s-1930s, 1970s, and 1998-2002. Each shoreline may represent a compilation of data from one or more sources for one or more dates provided by one or more agencies. Details regarding source are provided in the 'Data Quality Information' section of this metadata report. Shoreline vectors derived from historic sources (first three time periods) represent the high water line at the time of the survey, whereas modern shorelines (final time period) represent the mean high water line.

1. How should this data set be cited?

   Morton, Robert, Miller, Tara, and Moore, Laura, 2004, Vectorized Shoreline of Alabama Derived from 1978-1981 Source Data: Open-File Report 2004-1089, U.S. Geological Survey, Coastal and Marine Geology Program, U.S. Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, FL.

   Online Links:

   • <http://pubs.usgs.gov/of/2004/1089/>

   This is part of the following larger work.

   Morton, Robert, Miller, Tara, and Moore, Laura, 2004, National Assessment of Shoreline Change: Part 1, Historical Shoreline Changes and Associated Coastal Land Loss Along the U.S. Gulf of Mexico: Open-File Report 2004-1043, U.S. Geological Survey, Coastal and Marine Geology Program, U.S. Geological Survey, Center for Coastal and Watershed Studies.

   Online Links:

   • <http://pubs.usgs.gov/of/2004/1043/>
   • <http://coastal.er.usgs.gov/national-assessment/>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -88.326851

   East_Bounding_Coordinate: -87.450966

   North_Bounding_Coordinate: 30.382860

   South_Bounding_Coordinate: 30.221922

3. What does it look like?

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

   Beginning_Date: 1978

   Ending_Date: 1981

   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):

      • String (445)

   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 North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.
      

7. How does the data set describe geographic features?

   al1978_1981

   FID

   Internal feature number. (Source: ESRI)

   Sequential unique whole numbers that are automatically generated.

   Shape

   Feature geometry. (Source: ESRI)

   Coordinates defining the features.

   ID

   Feature number. (Source: U.S. Geological Survey.)

   Range of values
   Minimum:	1
   Maximum:	704

   TYPE

   Type of feature. (Source: U.S. Geological Survey)

   Value	Definition
   Shoreline	Vector shoreline.
   Baseline	Vector baseline.

   DATE_

   Year of survey. (Source: U.S. Geological Survey)

   Value	Definition
   01/01/1981	Feature surveyed in 1981.
   01/01/1978	Feature surveyed in 1978.

   DESCR

   Detailed description of the feature. (Source: U.S. Geological Survey)

   Describes additional characteristics of the feature.

   SOURCE

   Agency that provided feature or data used to create feature. (Source: U.S. Geological Survey)

   Value	Definition
   NOAA2	National Oceanographic and Atmospheric Administration (shoreline vectorization project)

   ACCURACY

   Position accuracy of feature. (Source: U.S. Geological Survey)

   Value	Definition
   0	The accuracy is not given or is not known.

   Range of values
   Units:	meters (m)

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Robert Morton
   • Tara Miller
   • Laura Moore

2. Who also contributed to the data set?

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

   U.S. Geological Survey, Center for Coastal and Watershed Studies
   600 4th Street South
   St. Petersburg, FL 33701
   USA
   

   (727) 803-8747 (voice)
   (727) 803-2032 (FAX)
   

   Hours_of_Service: Monday through Friday, 8 a.m. to 5 p.m., Eastern Standard Time

Historical shoreline change is considered to be a crucial element in studying the vulnerability of the national shoreline. These data are used in a shoreline change analysis for the USGS National Assessment Project.

1. From what previous works were the data drawn?

   (source 1 of 2)

   NOAA Coastal Services Center (NOAA2) Shoreline Data, NOAA Coastal Services Center, Charleston, SC.

   Online Links:

   • <http://www.csc.noaa.gov/shoreline/index.html>

   (source 2 of 2)

   NOAA Coastal Services Center (NOAA) NOAA Vectorization Project, NOAA Coastal Services Center, Charleston, SC.

   Other_Citation_Details: NOAA Contact Person - Mike Rink - (843) 740-1295

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

   (process 1 of 1)

   Shorelines from one or more sources were sought in an effort to develop a single shoreline for each time period. Digital shorelines, if available from another agency, were acquired. If no digital shorelines were available or if a data set was incomplete, T-sheets were requested from NOAA and received as scanned raster images. T-sheets were geo-registered using ERDAS Imagine geographic imaging software by placing 6-10 well-spaced ground control points at gridline intersections. Some T-sheets may have required additional coordinate transformation information from NOAA to account for datum offsets between historical datums (USSD) and modern datums (NAD27 or NAD83). Datum transformations were applied to GCP coordinates prior to registration. Total RMS error for the rectification process was maintained below 1 pixel, which translates to approximately 4m at a scale of 1:20,000 and 1.5m at a scale of 1:10,000. Geo-registered T-sheets were loaded in ArcView and vector shorelines were digitized.

   Quality assessments were performed and shorelines were edited to remove any overlap between adjacent shorelines. No edgematching between adjacent shorelines was attempted. Finally, shorelines from all sources were merged to produce a single shoreline for the period. The final shoreline was coded with 6 attribute fields (ID, Type, Date, Descr, Source, and Accuracy) required for the Digital Shoreline Analysis System (DSAS), which was used to calculate shoreline change rates. The attributes reflect the source of the data and the original survey year.

   Person who carried out this activity:
   

   U.S. Geological Survey, Center for Coastal and Watershed Studies
   600 4th Street South
   St. Petersburg, FL 33701
   USA
   

   (727) 803-8747 (voice)
   (727) 803-2032 (FAX)
   

   Hours_of_Service: Monday through Friday, 8 a.m. to 5 p.m., Eastern Standard Time

3. What similar or related data should the user be aware of?

1. How well have the observations been checked?

2. How accurate are the geographic locations?

   The maximum estimated positional error for this shoreline is 4m. Please visit our full report on shoreline change in the Gulf of Mexico (<http://pubs.usgs.gov/of/2004/1043/>), under the heading 'Reliability of the Results', for a complete explanation of the measurement error.

3. How accurate are the heights or depths?

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

   This shoreline data adequately represented the shoreline at the time of the survey. Remaining gaps in this data, if applicable, are a consequence of non-existing data or existing data that did not meet quality assurance standards.

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

   There is significant agreement of linework between adjacent shorelines. Shorelines were checked for accuracy, but no edgematching attempts were made between adjacent shorelines even if slight offsets existed.

Are there legal restrictions on access or use of the data?

Access_Constraints: None

Use_Constraints:

This data set is not to be used for navigational purposes.

Public domain data from the U.S. government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.

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

   U.S. Geological Survey, Center for Coastal and Watershed Studies
   600 4th Street South
   St. Petersburg, FL 33701
   USA
   

   (727) 803-8747 (voice)
   (727) 803-2032 (FAX)
   

   Hours_of_Service: Monday through Friday, 8 a.m. to 5 p.m., Eastern Standard Time

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

   USGS Open-File Report 2004-1089

3. What legal disclaimers am I supposed to read?

   Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, these data and information are provided with the understanding that they are not guaranteed to be usable, timely, accurate, or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.

   Neither the U.S. Government nor any agency thereof, 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 data, software, information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights.

   Trade, firm, or product names and other references to non-USGS products and services are provided for information only and do not constitute endorsement or warranty, express or implied, by the USGS, USDOI, or U.S. Government, as to their suitability, content, usefulness, functioning, completeness, or accuracy.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	ESRI Shapefile Seven files comprise the ArcView shapefile: <filename>.dbf, <filename>.shp, <filename>.shx, <filename>.prj, <filename>.avl, <filename>.sbx, <filename>.sbn Size: 0.202

   • Cost to order the data:

Dates:

Last modified: 05-Apr-2004

Metadata author:

U.S. Geological Survey, Center for Coastal and Watershed Studies
c/o Tara Miller
600 4th Street South
St. Petersburg, FL 33701
USA

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

Hours_of_Service: Monday through Friday, 8 a.m. to 5 p.m., Eastern Standard Time

Metadata standard:

FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Metadata extensions used:

• <http://www.esri.com/metadata/esriprof80.html>