Long and short-term shoreline change rate transects for the northern North Carolina coastal region (NCnorth), calculated with and without the proxy-datum bias using the Digital Shoreline Analysis System version 5.1

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Frequently anticipated questions:

What does this data set describe?

Title:
Long and short-term shoreline change rate transects for the northern North Carolina coastal region (NCnorth), calculated with and without the proxy-datum bias using the Digital Shoreline Analysis System version 5.1
Abstract:
The U.S. Geological Survey (USGS) has compiled national shoreline data for more than 20 years to document coastal change and serve the needs of research, management, and the public. Maintaining a record of historical shoreline positions is an effective method to monitor national shoreline evolution over time, enabling scientists to identify areas most susceptible to erosion or accretion. These data can help coastal managers and planners understand which areas of the coast are vulnerable to change.
This data release includes one new mean high water (MHW) shoreline extracted from lidar data collected in 2017 for the entire coastal region of North Carolina which is divided into four subregions: northern North Carolina (NCnorth), central North Carolina (NCcentral), southern North Carolina (NCsouth), and western North Carolina (NCwest). Previously published historical shorelines for North Carolina (Kratzmann and others, 2017) were combined with the new lidar shoreline to calculate long-term (up to 169 years) and short-term (up to 20 years) rates of change. Files associated with the long-term and short-term rates are appended with "LT" and "ST", respectively. A proxy-datum bias reference line that accounts for the positional difference in a proxy shoreline (e.g. High Water Line (HWL) shoreline) and a datum shoreline (e.g. MHW shoreline) is also included in this release.
Supplemental_Information:
Rate calculations were computed within a GIS using the Digital Shoreline Analysis System (DSAS) version 5.1, an ArcGIS extension developed by the U.S. Geological Survey. Long-term rates of shoreline change were calculated using a linear regression rate based on available shoreline data. Short-term rates of shoreline change were calculated with a linear regression rate using only datum-based MHW shoreline data, or an end point rate when less than 3 MHW shorelines were available. 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. This dataset consists of shoreline change rates calculated with DSAS version 5.1 and stored as a new transect layer. Original measurement transects are cast by DSAS from the baseline to intersect shoreline vectors, and the intersect data provide location and time information used to calculate rates of change.
  1. How might this data set be cited?
    Bartlett, Marie K., 20231023, Long and short-term shoreline change rate transects for the northern North Carolina coastal region (NCnorth), calculated with and without the proxy-datum bias using the Digital Shoreline Analysis System version 5.1: data release doi:10.5066/P9HYNUNV, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Bartlett, Marie K., Farris, Amy S., Weber, Kathryn M., and Henderson, Rachel E., 2023, USGS National Shoreline Change — 2017 lidar-derived mean high water shoreline and associated shoreline change data for coastal North Carolina: data release doi:10.5066/P9HYNUNV, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Bartlett, M.K., Farris, A.S., Weber, K.M., and Henderson, R.E., 2023, USGS National Shoreline Change — 2017 lidar-derived mean high water shoreline and associated shoreline change data for coastal North Carolina: U.S. Geological Survey data release, https://doi.org/P9HYNUNV.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.869032
    East_Bounding_Coordinate: -75.456965
    North_Bounding_Coordinate: 36.550983
    South_Bounding_Coordinate: 35.218439
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/64dfb358d34e5f6cd553bf4e?name=NCnorth_rates_browse.PNG (PNG)
    Map view of dataset
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date:
    Ending_Date: 2017
    Currentness_Reference:
    ground condition at the time of shoreline source data
  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. 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: -81.0
      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 meters
      The horizontal datum used is WGS_1984.
      The ellipsoid used is WGS_84.
      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?
    NCnorth_rates_LT
    Rates of long-term shoreline change are calculated by DSAS and stored in the transect file, using the distance measurements between shorelines and baseline at each DSAS transect. The shapefiles will have LT for long-term in filename. These attributes are for long-term shoreline change rates with and without the proxy-datum bias correction applied. Rate calculations without the proxy-datum bias correction applied will have "NB_" In the attribute field title. Vector Object Count: 3022 (Source: U.S. Geological Survey (USGS))
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Feature geometry. Rates are polyline shapefiles.
    BaselineID
    Unique identification number of the baseline segment. If BaselineID=0 no transects will be generated. Used by DSAS to determine transect ordering alongshore if multiple baseline segments exist. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:1
    GroupID
    Optional DSAS field used to aggregate transects on the basis of physical variations alongshore (for example, tidal inlets, change in coastal type, or hard stabilization features). This value was assigned by the user as an attribute to a baseline segment and results in a group average being reported in the DSAS summary text file. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:1
    Azimuth
    Assigned by DSAS to record the azimuth of the transect measure in degrees clockwise from North. If a transect position has been adjusted during the editing process, the azimuth value in the attribute table is updated automatically. (Source: USGS)
    Range of values
    Minimum:238.36
    Maximum:284.44
    Units:degress
    ShrCount
    Number of shorelines used to compute shoreline change metrics. (Source: USGS)
    Range of values
    Minimum:3
    Maximum:13
    TCD
    The Total Cumulative Distance (TCD) is the measure in meters along shore from the start of the baseline segment with an ID=1, and measured sequentially alongshore to the end of the final baseline segment. (Source: USGS)
    Range of values
    Minimum:1000
    Maximum:15570
    Units:meters
    SHAPE_Leng
    Length of feature in meters (UTM zone 17N, WGS 84) (Source: USGS)
    Range of values
    Minimum:56.036
    Maximum:1215.256
    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. Any shoreline points that are referenced to HWL were adjusted by the proxy-datum bias distance (meters) along the transect to correct for the offset between proxy-based HWL and datum-based MHW shorelines. 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: USGS)
    Range of values
    Minimum:-7.12
    Maximum:1.42
    Units:meters per year
    NB_LRR
    The LRR without the bias correction applied. Decimal values may be positive or negative, which is used to indicate landward (negative) or seaward (positive) direction from baseline origin. Reported in meters per year. (Source: USGS)
    Range of values
    Minimum:-7.05
    Maximum:1.47
    Units:meters per 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: USGS)
    Range of values
    Minimum:0.0
    Maximum:1.0
    NB_LR2
    The LR2 without the bias correction applied. (Source: USGS)
    Range of values
    Minimum:0.0
    Maximum:1.0
    LSE
    This quantity is the standard error of the regression, also known as the standard error of the estimate. To calculate it, the distance between each data point and the regression line is calculated. These distances are squared then summed. The sum is divided by the number of data point minus two. The square root is taken of the result. These are positive decimal values in meters. (Source: USGS)
    Range of values
    Minimum:1.19
    Maximum:345.3
    Units:meters
    NB_LSE
    The standard error of the regression (LSE) without the bias correction applied. (Source: USGS)
    Range of values
    Minimum:1.11
    Maximum:347.85
    Units:meters
    LCI90
    The 90 percent confidence interval (LCI90) is calculated by multiplying the standard error 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 and LCI90 = 0.7 could be reported as a rate of 1.2 (+/-) 0.7 meters/year. These are positive decimal values in meters. (Source: USGS)
    Range of values
    Minimum:0.02
    Maximum:4.29
    Units:meters
    NB_LCI90
    The LCI90 without the bias correction applied. These are positive decimal values in meters. (Source: USGS)
    Range of values
    Minimum:0.02
    Maximum:4.32
    Units:meters
    TransOrder
    Assigned by DSAS based on ordering of transects along the baseline. Allows user to sort transect data along the baseline from baseline start to baseline end. (Source: USGS)
    Range of values
    Minimum:19
    Maximum:3113
    NCnorth_rates_ST
    Rates of short-term shoreline change are calculated by DSAS and stored in the transect file, using the distance measurements between shorelines and baseline at each DSAS transect. These attributes are for short-term shoreline change rates without the proxy-datum bias correction applied. The shapefiles will have ST for short-term in filename. Vector Object Count: 3055 (Source: U.S. Geological Survey (USGS))
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Feature geometry. Rates are polyline shapefiles.
    BaselineID
    Unique identification number of the baseline segment. If BaselineID=0 no transects will be generated. Used by DSAS to determine transect ordering alongshore if multiple baseline segments exist. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:1
    GroupID
    Optional field used to aggregate transects on the basis of physical variations alongshore (for example, tidal inlets, change in coastal type, or hard stabilization features). This value was assigned by the user as an attribute to a baseline segment and results in a group average being reported in the DSAS summary text file. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:1
    Azimuth
    Assigned by DSAS to record the azimuth of the transect measure in degrees clockwise from North. If a transect position has been adjusted during the editing process, the azimuth value in the attribute table is updated automatically. (Source: USGS)
    Range of values
    Minimum:238.36
    Maximum:284.44
    Units:degrees
    ShrCount
    Number of shorelines used to compute shoreline change metrics. (Source: USGS)
    Range of values
    Minimum:2
    Maximum:3
    TCD
    The Total Cumulative Distance (TCD) is the measure in meters along shore from the start of the baseline segment with an ID=1, and measured sequentially alongshore to the end of the final baseline segment. (Source: USGS)
    Range of values
    Minimum:1000
    Maximum:155950
    Units:meters
    SHAPE_Leng
    Length of feature in meter units (UTM zone 17N, WGS 84) (Source: USGS)
    Range of values
    Minimum:23.534
    Maximum:799.876
    Units:meters
    EPR
    The end point rate (EPR) is calculated by determining the distance between the oldest and youngest shoreline on a DSAS transect and dividing by the time elapsed between the two shoreline dates.Decimal values may be positive or negative, which is used to indicate landward (negative) or seaward (positive) shoreline movement. Reported in meters per year. (Source: USGS)
    Range of values
    Minimum:-24.1
    Maximum:6.45
    Units:meters per year
    EPRunc
    An estimate of end point rate uncertainty. The shoreline uncertainties for the two positions used in the end point calculation are each squared, then added together (summation of squares). The square root of the summation of squares is divided by the number of years between the two shorelines. (Source: USGS)
    Range of values
    Minimum:0.18
    Maximum:0.9
    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. Any shoreline points that are referenced to HWL were adjusted by the proxy-datum bias distance (meters) along the transect to correct for the offset between proxy-based HWL and datum-based MHW shorelines. 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.LRR calculations require a minimum of 3 shorelines; less than 3 shorelines results in a “null” value, which is not a supported value in shapefile format. A value of 9999 in the LRR attribute field along with a ShrCount of 2 indicates the required number of shorelines to compute the linear regression rate was not met. (Source: USGS)
    Range of values
    Minimum:-17.7
    Maximum:5.99
    Units:meters per 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: USGS)
    Range of values
    Minimum:0.0
    Maximum:1.0
    LSE
    This quantity is the standard error of the regression, also known as the standard error of the estimate. To calculate it, the distance between each data point and the regression line is calculated. These distances are squared then summed. The sum is divided by the number of data point minus two. The square root is taken of the result. These are positive decimal values in meters. (Source: USGS)
    Range of values
    Minimum:0.0
    Maximum:120.7
    Units:meters
    LCI90
    The 90 percent confidence interval (LCI90) is calculated by multiplying the standard error 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 and LCI90 = 0.7 could be reported as a rate of 1.2 (+/-) 0.7 meters/year. These are positive decimal values in meters. (Source: USGS)
    Range of values
    Minimum:0.0
    Maximum:54.23
    Units:meters
    TransOrder
    Assigned by DSAS based on ordering of transects along the baseline. Allows user to sort transect data along the baseline from baseline start to baseline end. (Source: USGS)
    Range of values
    Minimum:1
    Maximum:3083
    Entity_and_Attribute_Overview:
    The entity and attribute information provided here describes the tabular data associated with long-term and short-term shoreline change rates. Please review the individual attribute descriptions for detailed information. All calculations for length are in meter units and were based on the UTM zone 18N WGS 84 projection (NCnorth, NCcentral, NCsouth) or UTM zone 17N WGS84 projection (NCwest).
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Marie K. Bartlett
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Marie K. Bartlett
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd
    Woods Hole, MA
    United States

    508-457-8700 x2306 (voice)
    mbartlett@usgs.gov

Why was the data set created?

This dataset describes the long-term (up to 169 years) and short-term (up to 20 years) shoreline change rates for the North Carolina coastal region, used to maintain a national database of shoreline change.

How was the data set created?

  1. From what previous works were the data drawn?
    NCnorth_historical_shorelines (source 1 of 1)
    Kratzmann, Meredith G., Himmelstoss, Emily A., and Thieler, E. Robert, 2017, National assessment of shoreline change – A GIS compilation of updated vector shorelines and associated shoreline change data for the Southeast Atlantic Coast: data release doi:10.5066/F74X55X7, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    These shorelines were combined with new lidar shoreline for 2017 and used within the Digital Shoreline Analysis System version 5.1 to produce long-term shoreline change rates.
  2. How were the data generated, processed, and modified?
    Date: 2022 (process 1 of 8)
    Step 1: Historical shoreline data covering the coast of North Carolina (Kratzmann and others, 2017) were compiled and merged into a single feature class (NCnorth_historical_shorelines) within a personal geodatabase in ArcMap v10.7.1. Historical shoreline data covers date range 1848-2010 and includes three lidar-derived shorelines (1997,2009,2010). The shoreline database was split into four regions: NCnorth, NCcentral, NCsouth, and NCwest, to account for changes in UTM zone and the complicated morphology of the coast. The data were projected using ArcToolbox v10.7.1 (Data Management Tools > Projections and Transformations > Feature > Project). Output projection for NCnorth, NCcentral, NCsouth = UTM zone 18N (WGS 84). Output projection for NCwest = UTM zone 17N (WGS 84); transformation = none. See associated source metadata (https://www.sciencebase.gov/catalog/item/58b89084e4b01ccd5500c2ac) for complete process steps for historical shoreline delineation. This process step and all subsequent process steps were performed by the same person - Marie K. Bartlett. Person who carried out this activity:
    Marie K. Bartlett
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x 2306 (voice)
    mbartlett@usgs.gov
    Date: 2022 (process 2 of 8)
    Step 2: The datum-based, MHW shoreline (see larger work citation, NCnorth_shoreline_2017) and historical shorelines compiled for long-term (LT) analysis (NCnorth_historical_shorelines) were confirmed to have the same attribute fields required for use in DSAS before they were merged into a single feature class using Esri's ArcToolbox > Data Management > General > Merge, output filename= NCnorth_shorelines. All shorelines have an uncertainty value listed in the attribute table that provides the horizontal uncertainty associated with the shoreline, regardless of the method used. Uncertainty for historical shorelines (1848-2010) is found in Kratzmann and others (2017). Data sources used in this process:
    • NCnorth_historical_shorelines
    • NCnorth_shoreline_2017
    Data sources produced in this process:
    • NCnorth_shorelines
    Date: 2023 (process 3 of 8)
    Step 3: Transect features for LT analysis were generated in a personal geodatabase using DSAS v5.1. DSAS parameters used: baseline layer= NCnorth_baseline, baseline group field=NULL, shoreline layer= NCnorth_shorelines, transect spacing=50 meters, default search distance=1000 meters, land direction=right, shoreline intersection=seaward. File produced = NCnorth_trans_LT. Some transects were manually edited for length, moved, or deleted using the editor toolbar in ArcMap. For additional details on these parameters, please see the DSAS help file distributed with the DSAS software, or visit the USGS website at:https://www.usgs.gov/centers/whcmsc/science/digital-shoreline-analysis-system-dsas Data sources used in this process:
    • NCnorth_baseline
    • NCnorth_shorelines
    Data sources produced in this process:
    • NCnorth_trans_LT
    Date: 2023 (process 4 of 8)
    Step 4: LT rate calculations were performed producing rates with and without the proxy-datum bias correction. DSAS parameters used: shoreline layer = NCnorth_shorelines, shoreline date field = Date_, shoreline uncertainty field name = Uncy, default accuracy = 5.1 meters, shoreline intersection = seaward, stats calculations = [LRR], shoreline threshold = 3, confidence interval=90%. Files produced = NCnorth_rates_LT, NCnorth_intersects_LT. The historical shoreline database contains both MHW and HWL shorelines thus a proxy-datum bias (PDB), stored as a line feature class, is appended to the reference baseline. The PDB is applied during rate calculation. For more information about the origin of the PDB see Ruggiero and List (2009), which is cross-referenced in this metadata file. Rate statistics are presented with and without the PDB correction applied, denoted in the long-term rates attribute table with a prefix of “NB_” or “No bias”. The bias uncertainty values are stored within the bias feature attribute table (see larger work citation, NCnorth_bias_feature). Data sources used in this process:
    • NCnorth_trans_LT
    • NCnorth_bias_feature
    • NCnorth_shorelines
    Data sources produced in this process:
    • NCnorth_rates_LT
    • NCnorth_intersects_LT
    Date: 2023 (process 5 of 8)
    Step 5: MHW shorelines (1997-2017) were exported from NCnorth_shorelines and renamed NCnorth_shorelines_ST for use in short-term (ST) shoreline change rate calculations. Data sources used in this process:
    • NCnorth_shorelines
    Data sources produced in this process:
    • NCnorth_shorelines_ST
    Date: 2023 (process 6 of 8)
    Step 6: Repeat Step 3 using NCnorth_shorelines_ST to generate ST transect features. Data sources used in this process:
    • NCnorth_baseline
    • NCnorth_shorelines
    Data sources produced in this process:
    • NCnorth_trans_ST
    Date: 2023 (process 7 of 8)
    Step 7: ST rate calculations were performed without a proxy-datum bias correction which was unnecessary, since only datum-based MHW shorelines (1997-2017) were used. DSAS parameters used: Shoreline layer = NCnorth_shorelines_ST, Shoreline date field = Date_, shoreline uncertainty field name = Uncy, default accuracy = 5.1 meters, shoreline intersection = seaward, stats calculations = [LRR], shoreline threshold = 2, confidence interval=90%. Files produced = NCnorth_rates_ST, NCnorth_intersects_ST. Data sources used in this process:
    • NCnorth_trans_ST
    • NCnorth_bias_feature
    • NCnorth_shorelines_ST
    Data sources produced in this process:
    • NCnorth_rates_ST
    • NCnorth_intersects_ST
    Date: 2023 (process 8 of 8)
    Step 8: The long and short-term rate transects were exported to shapefiles in ArcMap v10.7.1 by right-clicking the transect layer > data > export data. Coordinate system: UTM Zone 18N (WGS84)
  3. What similar or related data should the user be aware of?
    Himmelstoss, Emily A., Farris, Amy S., Henderson, Rachel E., Kratzmann, Meredith G., Ergul, Ayhan, Zhang, Ouya, Zichichi, Jessica L., and Thieler, E. Robert, 2021, Digital Shoreline Analysis System (version 5.1): U.S. Geological Survey Software: software release version 5.1, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Use the first two links to access the software. The third link directs to the DSAS project page. Current version of software at time of use was 5.1.
    Himmelstoss, Emily A., Henderson, Rachel E., Kratzmann, Meredith G., and Farris, Amy S., 20211019, Digital Shoreline Analysis System (version 5.1) User Guide: Open-File Report 2021-1091, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Refer to the DSAS user guide for more information about attribute requirements, accuracy reports, and feature creation.
    Himmelstoss, Emily A., Kraztmann, Meredith G., and Thieler, E. Robert, 20170718, National assessment of shoreline change—Summary statistics for updated vector shorelines and associated shoreline change data for the Gulf of Mexico and Southeast Atlantic coasts: Open-File Report 2017-1015, U.S. Geological Survey, Reston, VA.

    Online Links:

    Ruggiero, Peter, and List, Jeffrey H., 200909, Improving Accuracy and Statistical Reliability of Shoreline Position and Change Rate Estimates: Journal of Coastal Research vol. 255, Coastal Education and Research Foundation, Charlotte, NC.

    Online Links:

    Other_Citation_Details: ppg. 1069-1081

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 while creating the transect layer or during the calculation of shoreline change rates.
  2. How accurate are the geographic locations?
    The uncertainty of the linear regression rate is estimated by the elements LR2, LSE and LCI90. See the attribute definition of each for more information.
  3. How accurate are the heights or depths?
  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 for the region. Transects that did not intersect the minimum requirement of three shorelines, one of which must be a modern lidar shoreline, were omitted from this final dataset. Shoreline change rates data are provided where there are available shorelines to compute change metrics. Though the full database of shorelines was utilized for long-term rate analysis (1848-2017), gaps in shorelines or lack of lidar data in certain areas may mean that not all transects will incorporate every shoreline date in the rate calculations.
  5. How consistent are the relationships among the observations, including topology?
    These data were automatically generated by the DSAS v5.1 software and were visually inspected prior to rate calculations. Sometimes the intersection where transects cross the shoreline was manually edited in ArcMap (v10.7.1) to create a better orthogonal transect with respect to the general trend of the coastline. It is possible that a centimeter-scale offset may occur when projecting from outside of the spatial reference system used for analysis (UTM Zone 18N WGS84 or UTM Zone 17N WGS84). This is an artifact of the projection process; rate data are unaffected.

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 These data were generated for use within the DSAS v5.1 software. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. These data should not be used for any purpose other than that for which they are intended. The United States Geological Survey does not guarantee its validity. Assumptions, analyses, opinions, and actual outcomes may vary. The user should always verify actual data and exercise their own professional judgment when interpreting any outcomes. These data should not be used for any purpose other than that for which they are intended. The United States Geological Survey does not guarantee its validity. Assumptions, analyses, opinions, and actual outcomes may vary. The user should always verify actual data and exercise their own professional judgment when interpreting any outcomes. Please recognize the U.S. Geological Survey as the originator of the dataset. These data are not to be used for navigation.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: USGS ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The dataset contains the polyline shapefile of North Carolina long-term rates of change (NCnorth_rates_LT.shp, NCnorth_rates_ST.shp and other shapefile components), browse graphic (NCnorth_rates_browse.PNG, and the FGDC CSDGM metadata in XML format.
  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. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), and have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. 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?

Who wrote the metadata?

Dates:
Last modified: 23-Oct-2023
Metadata author:
Marie K. Bartlett
U.S. Geological Survey
384 Woods Hole Rd
Woods Hole, MA
USA

508-548-8700 x2306 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9HYNUNV/NCnorth_rates.faq.html>
Generated by mp version 2.9.51 on Mon Oct 23 17:02:50 2023