Entity_Type:
Entity_Type_Label: GA_transects_rates_ST.shp
Entity_Type_Definition:
Transects were automatically generated by DSAS at a 90 degree angle to the user-specified baseline using a smoothing algorithm to maintain roughly parallel transects that are orthogonal with respect to the baseline. These attributes are for short-term rates in Georgia (GA). Count = 2628.
Entity_Type_Definition_Source: U.S. Geological Survey
Attribute:
Attribute_Label: FID
Attribute_Definition:
Internal feature number used as a unique identifier of an object within a table primarily used in shapefiles.
Attribute_Definition_Source: Esri
Attribute_Domain_Values:
Unrepresentable_Domain:
Sequential unique whole numbers that are automatically generated.
Attribute:
Attribute_Label: Shape
Attribute_Definition: Feature geometry.
Attribute_Definition_Source: Esri
Attribute_Domain_Values:
Unrepresentable_Domain: Coordinates defining the features.
Attribute:
Attribute_Label: TransectID
Attribute_Definition:
A unique identification number for each transect. Values may not increment sequentially alongshore.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
Sequential unique whole numbers that are automatically generated.
Attribute:
Attribute_Label: BaselineID
Attribute_Definition:
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.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 1
Range_Domain_Maximum: unlimited
Attribute:
Attribute_Label: TransOrder
Attribute_Definition:
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.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0
Range_Domain_Maximum: unlimited
Attribute:
Attribute_Label: Azimuth
Attribute_Definition:
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.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0
Range_Domain_Maximum: 360
Attribute_Units_of_Measure: degrees
Attribute:
Attribute_Label: ShrCount
Attribute_Definition:
Number of shorelines used to compute shoreline change metrics. If ShrCount = 2 only an end point rate (EPR) is computed since there are not enough shorelines to compute a linear regression rate (LRR).
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 2
Range_Domain_Maximum: unlimited
Attribute:
Attribute_Label: SHAPE_Leng
Attribute_Definition: Length of feature in meter units (UTM zone 17N, WGS 84)
Attribute_Definition_Source: Esri
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0
Range_Domain_Maximum: unlimited
Attribute:
Attribute_Label: EPR
Attribute_Definition:
The end point rate is calculated by dividing the distance of shoreline movement by the time elapsed between two shorelines, the oldest and most recent only. The rate is reported in meters per year with positive values indicating accretion and negative values indicating erosion.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
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.
Attribute:
Attribute_Label: NB_EPR
Attribute_Definition:
End point rate-of-change statistic as described in the attribute EPR but without the proxy-datum bias applied. NB=no bias.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
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.
Attribute:
Attribute_Label: EPRunc
Attribute_Definition:
Describes the uncertainty of the reported end point rate in meters. 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. This result is reported as the confidence of the end point rate calculation (EPRunc).
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain: Positive decimal values in meters.
Attribute:
Attribute_Label: NB_EPRunc
Attribute_Definition:
The uncertainty of the reported end point rate in meters as described in the attribute EPRunc for rates without the proxy-datum bias applied (NB_EPR). NB=no bias.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain: Positive decimal values in meters.
Attribute:
Attribute_Label: LRR
Attribute_Definition:
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.
For short-term (ST) rates, an LRR value of 9999 in the attribute table means that value is Null. ArcGIS automatically changes Null values to zero values when a feature class is exported from a geodatabase to a shapefile. Zero values were changed to 9999 to clearly identify Null values. This scenario occurs when ShrCount = 2 and only an EPR rate is calculated.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
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.
Attribute:
Attribute_Label: NB_LRR
Attribute_Definition:
A linear regression rate-of-change statistic as described in the attribute LRR but without the proxy-datum bias applied. NB=no bias.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
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.
Attribute:
Attribute_Label: LR2
Attribute_Definition:
The R-squared statistic, or coefficient of determination, is the proportion 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).
For short-term (ST) rates, an LR2 value of 9999 in the attribute table means that LR2 is Null. ArcGIS automatically changes Null values to zero values when a feature class is exported from a geodatabase to a shapefile. Zero values were changed to 9999 to clearly identify Null values. This scenario occurs when ShrCount = 2 and only an EPR rate is calculated.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0
Range_Domain_Maximum: 1
Attribute:
Attribute_Label: NB_LR2
Attribute_Definition:
The R-squared statistic, or coefficient of determination, as described in the attribute LR2 but for NB (no bias) rates.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0
Range_Domain_Maximum: 1
Attribute:
Attribute_Label: LSE
Attribute_Definition:
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.
For short-term (ST) rates, an LSE value of 9999 in the attribute table means that LSE is Null. ArcGIS automatically changes Null values to zero values when a feature class is exported from a geodatabase to a shapefile. Zero values were changed to 9999 to clearly identify Null values. This scenario occurs when ShrCount = 2 and only an EPR rate is calculated.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain: Positive decimal values in meters.
Attribute:
Attribute_Label: NB_LSE
Attribute_Definition:
The standard error as described in the attribute LSE but for NB (no bias) rates.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain: Positive decimal values in meters.
Attribute:
Attribute_Label: LCI90
Attribute_Definition:
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.
For short-term (ST) rates, an LCI90 value of 9999 in the attribute table means that LCI90 is Null. ArcGIS automatically changes Null values to zero values when a feature class is exported from a geodatabase to a shapefile. Zero values were changed to 9999 to clearly identify Null values. This scenario occurs when ShrCount = 2 and only an EPR rate is calculated.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain: Positive decimal values in meters.
Attribute:
Attribute_Label: NB_LCI90
Attribute_Definition:
The 90 percent confidence interval as described in the attribute LCI90 but for NB (no bias) rates.
Attribute_Definition_Source: U.S. Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain: Positive decimal values in meters.
Entity_and_Attribute_Overview:
The entity and attribute information provided here describes the tabular data associated with short-term (approximately 30 years) shoreline change rates, as well as rates that incorporate the known unidirectional offset between proxy-based high water line features and datum-based mean high water line features (the proxy-datum bias), and rates that did not have the necessary information to correct for this offset (no bias). Please review the individual attribute descriptions for detailed information. All calculations for length are in meter units and were based on the UTM zone 17N WGS 84 projection. This region, Georgia, has two shapefiles describing rates: long-term (LT) and short-term (ST).
Entity_and_Attribute_Detail_Citation: U.S. Geological Survey
