Digital Shoreline Analysis System (DSAS) version 4.4 transects with short-term linear regression rate calculations for the exposed north coast of Alaska, from Icy Cape to Cape Prince of Wales

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Frequently anticipated questions:

What does this data set describe?

Title:
Digital Shoreline Analysis System (DSAS) version 4.4 transects with short-term linear regression rate calculations for the exposed north coast of Alaska, from Icy Cape to Cape Prince of Wales
Abstract:
This dataset consists of short-term (less than 37 years) shoreline change rates for the north coast of Alaska from Icy Cape to Cape Prince of Wales. Rate calculations were computed within a GIS using the Digital Shoreline Analysis System (DSAS) version 4.4, an ArcGIS extension developed by the U.S. Geological Survey. Rates of shoreline change were calculated using a linear regression rate-of-change (lrr) method based on available shoreline data between 1980s and 2016. A reference baseline was used as the originating point for the orthogonal transects cast by the DSAS software. The transects intersect each shoreline establishing measurement points, which are then used to calculate rates of change.
Supplemental_Information:
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the dataset in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Snyder, Alexander G., and Gibbs, Ann E., 20191227, Digital Shoreline Analysis System (DSAS) version 4.4 transects with short-term linear regression rate calculations for the exposed north coast of Alaska, from Icy Cape to Cape Prince of Wales: data release DOI: 10.5066/P9H1S1PV, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    This is part of the following larger work.

    Snyder, Alexander G., and Gibbs, Ann E., 2019, National Assessment of Shoreline Change: A GIS compilation of vector shorelines and associated shoreline change data for the north coast of Alaska, Icy Cape to Cape Prince of Wales: data release https://doi.org/10.5066/P9H1S1PV, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -168.127648476711
    East_Bounding_Coordinate: -162.826969308734
    North_Bounding_Coordinate: 67.847383257894
    South_Bounding_Coordinate: 65.6001728650679
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 01-Jul-1948
    Ending_Date: 03-Sep-2016
    Currentness_Reference:
    ground condition.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: polyline shapefile
  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 (8920)
    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 0.0196106556. Longitudes are given to the nearest 0.0558147069. 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.
  7. How does the data set describe geographic features?
    Attribute Table
    Table containing attribute information associated with the dataset. (Source: Producer defined)
    FID
    Index number unique to each record in the attribute table. (Source: Assigned by ArcMap)
    Range of values
    Minimum:0
    Maximum:8919
    Shape
    Defines what type of spatial information is associated with this record (for example, polyline, polygon, point). (Source: Assigned by ArcMap.)
    ValueDefinition
    PolylineA shape defined by one or more paths, in which a path is a series of connected segments.
    BaselineID
    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:107
    Maximum:121
    Group_
    Region ID as defined in Gibbs and others (2019). (Source: Producer defined.)
    ValueDefinition
    6Asikpak Lagoon to Sheshalik Spit (CAKR)
    8Sullivan Lake to Cape Prince of Wales (BELA)
    TransOrder
    Assigned by DSAS based on ordering of transects along the baseline. Used to allow user to sort transect data along the baseline from baseline start to baseline end. (Source: Producer defined.)
    Range of values
    Minimum:9100
    Maximum:24612
    ProcTime
    Date and time (YYYY/MM/DD HH:MM:SS) a transect was processed. This value is automatically assigned by the DSAS extension. (Source: Producer defined.)
    Range of values
    Minimum:2018/12/19 16:46:36
    Maximum:2018/12/19 16:50:12
    Autogen
    Assigned by DSAS to indicate whether or not a transect was automatically created by DSAS (1= transect was auto generated by DSAS; 0=transect was not auto-generated). (Source: Producer defined)
    ValueDefinition
    0Transect was not auto-generated by DSAS.
    1Transect was auto-generated by DSAS.
    StartX
    Easting component of the coordinate (in NAD83 UTM Zone 3) defining the start of the transect. (Source: Producer defined)
    Range of values
    Minimum:356104.98
    Maximum:594767.23
    StartY
    Northing component of the coordinate (in NAD83 UTM Zone 3) defining the start of the transect. (Source: Producer defined)
    Range of values
    Minimum:7278897.71
    Maximum:7525502.8
    EndX
    Easting component of the coordinate (in NAD83 UTM Zone 3) defining the end of the transect. (Source: Producer defined)
    Range of values
    Minimum:356604.89
    Maximum:594621.54
    EndY
    Northing component of the coordinate (in NAD83 UTM Zone 3) defining the end of the transect. (Source: Producer defined)
    Range of values
    Minimum:7278815.88
    Maximum:7525858.8
    Azimuth
    The azimuth of the transect, defined in degrees. (Source: Producer defined)
    Range of values
    Minimum:7.34
    Maximum:350.31
    ShoreType
    User defined shoreline type. (Source: Producer defined.)
    ValueDefinition
    Exposed Barrier BeachSand or gravel deposit extending across a body of water.
    Exposed Barrier IslandOffshore deposits of sand or sediment that run parallel to the coastline.
    Exposed Barrier SpitSand or gravel deposit extending from the mainland into a body of water.
    Exposed MainlandA large, continuous extent of land that does not include offshore islands or other detached territories.
    Exposed Mainland, rockyA large, continuous extent of rocky land that does not include offshore islands or other detached territories.
    SHAPE_Leng
    Length of the polyline represented by this record. (Source: Producer defined.)
    Range of values
    Minimum:112.125216
    Maximum:792.974111
    Units:Meters
    TransectID
    Same value as ObjectID. Used as a permanent and unique identification number for each transect in the output rates table calculated by DSAS. This attribute was used as the common field when joining the rates table (.dbf) to the transect feature class in a geodatabase. (Source: Thieler and others (2009).)
    Range of values
    Minimum:1
    Maximum:6729
    TCD
    Total cumulative distance in meters from start of baseline to transect location. (Source: Thieler and others (2009).)
    Range of values
    Minimum:250
    Maximum:380069.24
    Units:Meters
    SCE
    The shoreline change envelope reports a distance, not a rate. The SCE is the distance between the shoreline farthest from and closest to the baseline at each transect. This represents the total change in shoreline movement for all available shoreline positions and is not related to their dates. (Source: Thieler and others (2009).)
    Range of values
    Minimum:0.9
    Maximum:631.47
    Units:Meters
    NSM
    The Net shoreline movement (NSM) reports the distance between the oldest and youngest shorelines for each transect. This represents the total distance between the oldest and youngest shorelines. If this distance is divided by the number of years elapsed between the two shoreline positions, the result is the End Point Rate (EPR). (Source: Thieler and others (2009).)
    Range of values
    Minimum:-631.47
    Maximum:227
    Units:Meters
    LRR
    A linear regression rate-of-change statistic was calculated by fitting a least-squares regression line to all shoreline points for a particular transect. The best-fit regression line is placed so that the sum of the squared residuals (determined by squaring the offset distance of each data point from the regression line and adding the squared residuals together) is minimized. The linear regression rate is the slope of the line. The rate is reported in meters per year with positive values indicating accretion and negative values indicating erosion. (Source: Thieler and others (2009).)
    Range of values
    Minimum:-16.01
    Maximum:7.22
    Units:Meters/year
    LR2
    The R-squared statistic, or coefficient of determination, is the percentage of variance in the data that is explained by a regression. It is a dimensionless index that ranges from 1.0 to 0.0 and measures how successfully the best-fit line accounts for variation in the data. The smaller the variability of the residual values around the regression line relative to the overall variability, the better the prediction (and closer the R-squared value is to 1.0). (Source: Thieler and others (2009).)
    Range of values
    Minimum:0
    Maximum:1
    LSE
    The predicted (or estimated) values of y (the distance from baseline in meters) are computed for each shoreline point by using the values of x (the shoreline date) and solving the equation for the best-fit regression line (y=mx+b). The standard error is also called the standard deviation. (Source: Thieler and others (2009).)
    Range of values
    Minimum:0
    Maximum:191.13
    LCI90
    The standard error of the slope with confidence interval describes the uncertainty of the reported rate. The LRR rates are determined by a best-fit regression line for the shoreline data at each transect. The slope of this line is the reported rate of change (in meters/year). The confidence interval (LCI) is calculated by multiplying the standard error (also called the standard deviation) of the slope by the two-tailed test statistic at the user-specified 90 percent confidence. This value is often reported in conjunction with the slope to describe the confidence of the reported rate. For example: LRR = 1.2 LCI90 = 0.7 could be reported as a rate of 1.2 (+/-) 0.7 meters/year. (Source: Thieler and others (2009).)
    Range of values
    Minimum:0
    Maximum:43.941
    CalcEra
    Decade (era) of shorelines used to calculate shoreline change rates. (Source: Producer defined.)
    ValueDefinition
    1980s, 2000s, 2010sShorelines used from specified decades.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Alexander G. Snyder
    • Ann E. Gibbs
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

Beach erosion is a persistent problem along most open-ocean shores of the United States. Along the Arctic coast of Alaska, coastal erosion is widespread and is threatens Native communities, defense and energy-related infrastructure, and coastal habitat. As coastal populations continue to expand and infrastructure and habitat are increasingly threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There also is a need for a comprehensive analysis of shoreline change with metrics that are consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical shoreline changes along the open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline change so that periodic, systematic, and internally consistent updates regarding coastal erosion and land loss can be made nationally.

How was the data set created?

  1. From what previous works were the data drawn?
    DSAS baseline (source 1 of 2)
    U.S. Geological Survey, 2019, Offshore baseline generated to calculate shoreline change rates for the north coast of Alaska, Icy Cape to Cape Prince Wales.: U.S. Geological Survey, online.

    Online Links:

    Type_of_Source_Media: Digital Resources
    Source_Contribution: DSAS baseline used for calculation of shoreline change rates.
    shorelines (source 2 of 2)
    U.S. Geological Survey, 2019, Shorelines from 1948 to 2016 for the north coast of Alaska, Icy Cape to Cape Prince Wales.: U.S. Geological Survey, online.

    Online Links:

    Type_of_Source_Media: Digital Resources
    Source_Contribution: Shorelines used for calculation of shoreline change rates.
  2. How were the data generated, processed, and modified?
    Date: 2019 (process 1 of 8)
    Transect features were generated using DSAS v4.4 in ArcMap v10.6. Parameters Used: baseline, transect spacing=50 meters, transect length=500m, cast direction=onshore, baseline location=offshore, cast method=smoothed, smoothing distance=50 meters. For additional details on these parameters, please see the DSAS help file distributed with the DSAS software. Data sources used in this process:
    • DSAS Baseline
    Date: 2019 (process 2 of 8)
    Some transects were manually edited to ensure that intersected all shorelines and were as close to perpendicular as possible. Data sources used in this process:
    • shorelines
    Date: 2019 (process 3 of 8)
    Rate calculations performed using DSAS v4.4 in ArcMap v10.6 on selected shoreline features. Parameters Used: shoreline layer=WestChukchi_shorelines, shoreline date field=DATE_, shoreline uncertainty field name=Uncy, the default accuracy= 0 meters, stats calculations=SCE/NSM/LRR, confidence interval=90%. Data sources used in this process:
    • shorelines
    Date: 2019 (process 4 of 8)
    Shoreline change rates table was joined to the transect feature class in ArcMap v10.6 by right-clicking on the transect layer; joins and relates; join; join attributes from a table. Parameters: join field - ObjectID; field in table: TransectID; join options - keep only matching records.
    Date: 2019 (process 5 of 8)
    The joined transect feature class was exported to a shapefile in ArcMap v10.6 by right-clicking the transect layer; data; export data, permanently linking the joined rate fields to the transect attribute table.
    Date: 2019 (process 6 of 8)
    The exported transect shapefile was projected in Esri's ArcToolbox (v10.6); Data Management Tools; Projections and Transformations; Feature; Project. Parameters: input projection - UTM zone 3 (NAD83); output projection - geographic coordinates (WGS84); transformation = WGS_1984_(ITRF00)_To_NAD_1983.
    Date: 19-Oct-2020 (process 7 of 8)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. 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
    Date: 13-Oct-2021 (process 8 of 8)
    Performed minor edits to the metadata to correct typos. No data were changed Person who carried out this activity:
    U.S. Geological Survey
    Attn: Susan A. Cochran
    Geologist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Gibbs, Ann E., Snyder, Alexander G., and Richmond, Bruce M., 2019, National Assessment of Shoreline Change: Historical Shoreline Change Along the North Coast of Alaska, Icy Cape to Cape Prince of Wales..

    Online Links:

    • https:/doi.org/10.3133/ofr20191146

    Other_Citation_Details:
    Gibbs, A.E., Snyder, A.G., Richmond, B.M., 2019, National Assessment of Shoreline Change: Historical Shoreline Change Along the North Coast of Alaska, Icy Cape to Cape Prince of Wales: U.S. Geological Survey Open-File Report 2019-1146.
    Thieler, Robert E., Himmelstoss, Emily A., Zichichi, Jessica L., and Ergul, Ayhan, 2009, Digital Shoreline Analysis System (DSAS) version 4.0 - An ArcGIS extension for calculating shoreline change.

    Online Links:

    Other_Citation_Details:
    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 Open-File Report 2008-1278.

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

  1. How well have the observations been checked?
    The attributes 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 transect serves as a reference point along which measurements are calculated 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?
    The transect serves as a reference point along which measurements are calculated by the Digital Shoreline Analysis System (DSAS) software. It does not correspond to any real-world feature.
  4. Where are the gaps in the data? What is missing?
    This dataset contains the transects automatically generated by the DSAS software application that were used to calculate shoreline change rates along the coast of Alaska, between Icy Cape and Cape Prince of Wales, where shoreline position data were available. Additional transects may have been generated but did not intersect the shoreline dates specified.
  5. How consistent are the relationships among the observations, including topology?
    All polylines have a unique identification attribute (ID). This field is used by the Digital Shoreline Analysis System (DSAS) to measure shoreline change.

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:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? These data are available in shapefile format contained in a single zip file, which also includes CSDGM FGDC-compliant metadata.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (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.
  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-2021
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P9H1S1PV/WestChukchi_exposed_STlrr_rates_metadata.faq.html>
Generated by mp version 2.9.50 on Thu Oct 14 14:47:22 2021