Alaska: East Chukchi Sea Coast (Point Barrow to Icy Cape) transects with long-term (LT) linear regression rate calculations for the sheltered coast

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Frequently anticipated questions:

What does this data set describe?

Title:
Alaska: East Chukchi Sea Coast (Point Barrow to Icy Cape) transects with long-term (LT) linear regression rate calculations for the sheltered coast
Abstract:
This dataset consists of long-term (~65 years) shoreline change rates for the north coast of Alaska between Point Barrow and Icy Cape. Rate calculations were computed within a GIS using the Digital Shoreline Analysis System (DSAS) version 4.3, an ArcGIS extension developed by the U.S. Geological Survey. Long-term rates of shoreline change were calculated using a linear regression rate-of-change method based on available shoreline data between 1947 and 2012. 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 long-term rates.
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 data set 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?
    Gibbs, Ann E., Ohman, Karin A., Coppersmith, Ryan, and Richmond, Bruce M., 2017, Alaska: East Chukchi Sea Coast (Point Barrow to Icy Cape) transects with long-term (LT) linear regression rate calculations for the sheltered coast: data release 10.5066/F72Z13N1, U.S. Geological Survey, Coastal and Marine Geology Program, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz and Menlo Park, CA.

    Online Links:

    This is part of the following larger work.

    Gibbs, Ann E., Ohman, Karin A., Coppersmith, Ryan, and Richmond, Bruce M., 2017, National Assessment of Shoreline Change: A GIS compilation of Updated Vector Shorelines and Associated Shoreline Change Data for the North Coast of Alaska, U.S. Canadian Border to Icy Cape: data release 10.5066/F72Z13N1, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -161.913974382
    East_Bounding_Coordinate: -158.28672056
    North_Bounding_Coordinate: 70.8613626619
    South_Bounding_Coordinate: 70.2367560785
    Description_of_Geographic_Extent: North coast of Alaska between the Point Barrow and Icy Cape
  3. What does it look like?
    EastChukchiExtent.jpg (JPEG)
    Map of the East Chukchi subregion of the north coast of Alaska shoreline change assessment area.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1947
    Ending_Date: 2012
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data (polyline)
  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 (2308)
    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 0.0196094356. Longitudes are given to the nearest 0.0565341806. 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 data set. (Source: Producer defined)
    OBJECTID
    Internal feature number generated for each row of the transect attribute table when stored as a feature class in a geodatabase. This value is the common attribute field when joining to the TransectID value in short-term results output table calculated by DSAS. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:2389
    BaselineID
    Unique identification number of the baseline segment. Used by DSAS to determine transect ordering alongshore if multiple baseline segments exist. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:29
    Group_
    Region ID as defined in Gibbs and Richmond (2017). (Source: U.S. Geological Survey)
    ValueDefinition
    10Peard Bay to Icy Cape region
    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: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:2389
    ProcTime
    Date and time (YYYY/MM/DD HH:MM:SS) a transect was processed. This value is automatically assigned by the DSAS extension. (Source: U.S. Geological Survey)
    Range of values
    Minimum:2011/05/20 15:05:33
    Maximum:2015/11/17 13:27:04
    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: U.S. Geological Survey)
    ValueDefinition
    0Transect was not auto-generated by DSAS
    1Transect was auto-generated by DSAS
    StartX
    Unknown (Source: Producer defined)
    Range of values
    Minimum:390369.057424
    Maximum:525716.42
    StartY
    Unknown (Source: Producer defined)
    Range of values
    Minimum:7794733.89994
    Maximum:7861674.79964
    EndX
    Unknown (Source: Producer defined)
    Range of values
    Minimum:390813.693618
    Maximum:526163.84
    EndY
    Unknown (Source: Producer defined)
    Range of values
    Minimum:7794184.75963
    Maximum:7861944.46
    Azimuth
    Unknown (Source: Producer defined)
    Range of values
    Minimum:12.09
    Maximum:358.46
    ShoreType
    User defined shoreline type (Source: U.S. Geological Survey)
    ValueDefinition
    Sheltered MainlandA large, continuous extent of land that does not include offshore islands or other detached territories and is sheltered from direct wave energy by offshore islands.
    Shape_Leng
    Length of the transect created by DSAS (Source: Producer defined)
    Range of values
    Minimum:113.610765306
    Maximum:592.00907007
    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: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:2389
    TCD
    Total cumulative distance in meters from start of baseline to transect location. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:189221.77
    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: U.S. Geological Survey)
    Range of values
    Minimum:-2.10
    Maximum:1.81
    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: U.S. Geological Survey)
    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: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:78.16
    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: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:11.172
    CalcEra
    Decade (era) of shorelines used to calculate shoreline change rates. (Source: U.S. Geological Survey)
    ValueDefinition
    1940s, 1980s, 2010sUnknown
    Entity_and_Attribute_Overview:
    All calculations for length are in meter units and were based on the coincident UTM zone WGS84
    Entity_and_Attribute_Detail_Citation: Unknown

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Gibbs, Ann E.
    • Ohman, Karin A.
    • Coppersmith, Ryan
    • Richmond, Bruce M.
  2. Who also contributed to the data set?
    U.S. Geological Survey
  3. To whom should users address questions about the data?
    Ann E. Gibbs
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA
    USA

    831-460-7540 (voice)
    831-427-4748 (FAX)
    agibbs@usgs.gov

Why was the data set created?

The Arctic Coastal Plain of northern Alaska is an area of strategic economic importance to the United States, is home to remote Native American communities, and encompasses unique habitats of global significance. Coastal erosion along the north coast of Alaska is chronic, widespread, may be accelerating, and is threatening defense and energy-related infrastructure, natural shoreline habitats, and Native Alaskan communities. There is an increased demand for accurate information regarding past and present shoreline changes across the United States. To meet these national needs, the Coastal and Marine Geology Program of the U.S. Geological Survey (USGS) is compiling existing reliable historical shoreline data along sandy shores of the conterminous United States and parts of Alaska and Hawaii under the National Assessment of Shoreline Change project. There is no widely accepted standard for analyzing shoreline change. Existing shoreline data measurements and rate calculation methods vary from study to study and prevent combining results into state-wide or regional assessments. The impetus behind the National Assessment project was to develop a standardized method of measuring changes in shoreline position that is consistent from coast to coast. The goal was to facilitate the process of periodically and systematically updating the results in an internally consistent manner.

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, 2017, Offshore baseline for the sheltered Eastern Chukchi Sea, Alaska coastal region (Point Barrow to Icy Cape) generated to calculate shoreline change rates: U.S. Geological Survey, online.

    Online Links:

    Type_of_Source_Media: Digital Resources
    Source_Contribution: DSAS baseline used for calculation of shoreline change rates.
    DSAS shoreline (source 2 of 2)
    U.S. Geological Survey, 2017, Shorelines of the Eastern Chukchi Sea, Alaska coastal region (Point Barrow to Icy Cape) used in shoreline change analysis: U.S. Geological Survey, online.

    Online Links:

    Type_of_Source_Media: Digital Resources
    Source_Contribution:
    DSAS shoreline file used for calculation of shoreline change rates.
  2. How were the data generated, processed, and modified?
    Date: 2016 (process 1 of 8)
    Transect Features Generated using DSAS v4.3 in ArcMap v10.3. Parameters Used: baseline layer=UTMX_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.
    Date: 2016 (process 2 of 8)
    Some transects did not intersect all shorelines at the default transect length. These transects were manually lengthened in an edit session using standard editing tools in ArcMap v10.3. Some transects intersected the shorelines at an oblique angle. These transects were manually adjusted to a more shore-normal position in an edit session using standard editing tools in ArcMap v10.3.
    Date: 2016 (process 3 of 8)
    Rate calculations performed using DSAS v4.3 in ArcMap v10.3 on selected shoreline features. Parameters Used: shoreline layer= EastChukchi_shorelines, shoreline date field=DATE_, shoreline uncertainty field name=Uncy, the default accuracy= 0 meters, shoreline intersection parameters=nearest, stats calculations=[Linear Regression Rate (LRR)], shoreline threshold=4, confidence interval=90%,
    Date: 2016 (process 4 of 8)
    Shoreline change rates table was joined to the transect feature class in ArcMap v10.3 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: 2016 (process 5 of 8)
    The joined transect feature class was exported to a shapefile in ArcMap v10.3 by right-clicking the transect layer > data > export data, permanently linking the joined rate fields to the transect attribute table.
    Date: 2016 (process 6 of 8)
    The exported transect shapefile was projected in Esri's ArcToolbox (v10.3) > Data Management Tools > Projections and Transformations > Feature > Project. Parameters: input projection - UTM zone XN (NAD83; where X is the corresponding UTM Zone); 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: 26-Mar-2026 (process 8 of 8)
    The metadata title was modified to move the location to the beginning of the title. This was done to meet new system requirements as ScienceBase is migrated to a new platform, and to keep datasets grouped by location on the new data release landing page. (20260326). Person who carried out this activity:
    Manda Au
    U.S. Geological Survey
    Data Management Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7575 (voice)
    mau@usgs.gov
  3. What similar or related data should the user be aware of?
    Gibbs, A.E., and B.M., Richmond, 2017, National Assessment of Shoreline Change: Summary Statistics for Updated Vector Shorelines and Associated Shoreline Change Data for the North Coast of Alaska, U.S.--Canadian Border to Icy Cape: Open-File Report 2017-1107, U.S. Geological Survey, Reston, VA.

    Online Links:

    Gibbs, Ann E., and Richmond, Bruce M., 2015, National Assessment of Shoreline Change: Historical Shoreline Change along the North Coast of Alaska, U.S.--Canadian Border to Icy Cape: Open-File Report 2015-1048, U.S. Geological Survey, Reston, VA.

    Online Links:

    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: Open-File Report 2008-1278, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details: Current version 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 attributes of this dataset are based on the field requirements of the Digital Shoreline Analysis System and were automatically generated by the software during the generation of the transect layer or during the calculation of shoreline change rates performed by the software.
  2. How accurate are the geographic locations?
    A formal accuracy assessment of the horizontal positional information in the data set has not been conducted.
  3. How accurate are the heights or depths?
    A formal accuracy assessment of the vertical positional information in the data set has either not been conducted, or is not applicable.
  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 sections of the north coast of Alaska, between the U.S.-Canadian border and Icy Cape, 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?
    These data were generated using DSAS v4.3, an automated software program which does not perform checks for fidelity of the input features. The transects were visually inspected and sometimes manually adjusted within a standard ArcMap edit session to adjust the position at which an individual transect intersected the shorelines.

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 - Science Base
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    CA

    888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? EastChukchi_sheltered_LT_rates.shp
  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: 26-Mar-2026
Metadata author:
Ann E. Gibbs
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Geologist
2885 Mission Street
Santa Cruz, CA
USA

831-460-7540 (voice)
831-427-4748 (FAX)
agibbs@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_F72Z13N1/EastChukchi_sheltered_LT_rates.faq.html>
Generated by mp version 2.9.51 on Fri Apr 24 15:25:53 2026