South Atlantic Water Science Center - North Carolina Office

Rating Unsaturated Zone and Watershed Characteristics of Public Water Supplies - Updates

Metadata - Characterizing the Watershed Characteristics of North Carolina
Land-surface Percent Slope Category Ratings

• Identification Information
• Data Quality Information
• Spatial Data Organization Information
• Spatial Reference Information
• Entity and Attribute Information
• Distribution Information
• Metadata Reference Information

Metadata elements shown with blue text are defined in the Federal Geographic Data Committee's (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM). Elements shown with green text are defined in the ESRI Profile of the CSDGM. Elements shown with a green asterisk (*) will be automatically updated by ArcCatalog. ArcCatalog adds hints indicating which FGDC elements are mandatory; these are shown with gray text.

Identification Information:

Citation:

Citation information:

Originators: Silvia Terziotti

*Title:

slopesw

*File or table name: slopesw

Publication date: 2009

Edition: Version 1.0, January 26, 2001

*Geospatial data presentation form: raster digital data

Publication information:

Publication place: Raleigh, NC

Publisher: U.S. Geological Survey

*Online linkage: \\Igsavbewfs001\Work\SWAP_updates\FinalLayers\SW\slopesw

Description:

Abstract:

Percent-slope classes to characterize watersheds is one of 6 data
sets updated for the North Carolina Public Water Supply, Source
Water Assessment Program. These data are used to rate the susceptibility of
public water supplies in North Carolina to contamination.

The original dataset was produced in 2000. This version is updated to reflect new data sources.

This data set represents the ratings applied to the land-surface slope classes for use in the rating of the unsaturated zone for public ground-water suppliers.

Land-surface slope influences the amount of precipitation that ponds on the land surface and infiltrates to contribute to ground water, or runs off the land surface as overland flow to surface water. When all other factors are the same, precipitation infiltrates into
the subsurface in areas characterized by low slope; precipitation runs off land surface in areas characterized by high slope. For surface-water systems, the greater the likelihood that water will run off the land surface, (that is, the higher the slope), the higher the rating applied on a scale of 1 to 10.

Purpose:

This data set is to be used in a hydrologic analysis with other
data sets to rate the unsaturated zone for public ground-water
supplies and watershed characteristics for public surface-water
supplies in North Carolina.

For ground-water supplies, the factors used to rate susceptibility to
contamination include vertical hydraulic conductance, land-surface slope,
land cover, and land use.  The selected factors used to devise ratings for
surface-water supplies' susceptibility to contamination are average annual
precipitation, land-surface slope, land cover, land use, and ground-water
contribution.

Supplemental information:

The 1996 Amendments to the Safe Drinking Water Act require that each state prepare a source-water assessment for all public water supplies. States are required to (1) delineate source areas supplying wells and surface-water intakes, (2) inventory potential contaminant sources within the delineated source areas, and (3) determine the susceptibility of wells or intakes to the inventoried potential contaminant sources.

In North Carolina, the lead agency charged with this task is the Public Water Supply Section (PWSS) of the Division of Environmental Health, Department of Environment and Natural Resources (DENR). North Carolina's Source Water Assessment Program (SWAP) provides assessments of each public drinking water intake in North Carolina. These assessments provide a relative susceptibility rating calculated using state-wide data.

The U.S. Geological Survey (USGS) cooperated with the PWSS to provide components of the inherent vulnerability rating that was used with the contaminant rating to determine the overall susceptibility rating of source water supplies. To assist the PWSS with rating ground water inherent vulnerability, the USGS compiled the unsaturated zone rating based on the following characteristics: vertical hydraulic conductance, depth to water, land surface slope, land use and land cover. The watershed characteristic rating includes average annual precipitation, land surface slope, land use, land cover and groundwater contribution.

The SWAP program has planned for updates to the initial ratings as conditions change and new data sources become available. The initial data used to calculate the unsaturated zone ratings and watershed characteristics ratings were compiled from sources from the late 1990's. Critical data layers have been updated since the ratings were calculated. These improved data layers need to be used in the ongoing update of the susceptibility ratings.

Overlay and index methods for rating susceptibility to contamination
of the unsaturated zone for ground-water suppplies, and watershed
characteristics for surface-water supplies were derived for use
by the State of North Carolina in assessing more than 11,000 public
water-supply wells and approximately 245 public surface-water intakes.
Factors that influence the inherent vulnerability of ground water and
surface water were selected and assigned ratings on a scale of 1 to 10.
These factors were then assigned weight to reflect their relative influence
on inherent vulnerability and the reliability of the data.  The
values for each factor were obtained from geographic information
system (GIS) data layers that were transformed into ARC/INFO
raster data sets known as grids. These raster data sets have
30-meter by 30-meter cells, and each cell is assigned a weighted-
factor value.

Limitations --

The overlay and index methods of unsaturated zone and watershed
characteristics ratings are broad-stroke methods that assess
vulnerability on the basis of expert opinion. The methods aslo have
limitations in the age and scale of the hydrologic and geographic
data. But the most significant limitation of the methods used
is that no statistical confirmation of the results have been
performed.

ELEVATION:

Since the initial compilation of land-surface slope classes in 2000, a new source of elevation data has become available. In 2001, the State of North Carolina, Floodplain Mapping Program began to produce a digital elevation model (DEM) from lidar data to produce digital flood maps. Lidar data is an airborne data collection method that collects elevation data at a very high degree of accuracy (20 cm vertical accuracy). This creates an elevation surface that captures very subtle changes in elevation, and much more detailed changes in elevation. The slopes derived from a lidar DEM tend to capture areas of high slope that occur over short distances, such as ridges on stream banks, that earlier mapping techniques were not able to record. This tends to increase slope values over a study area.

SLOPE:

The slope dataset was created from the individual tiles of 20 foot elevation horizontal post spacing. The data is freely downable at the North Carolina Floodplain Mapping Information System site (http://ncfloodmaps.com). The elevation tiles were merged to encompass the entire State of North Carolina, projected from a North Carolina state-plane coordinate system in feet, to a North Carolina state-plane coordinate system in meters, and resampled to a 30 meter cell size. The elevation values were also recalculated from feet to meters so that the horizontal and vertical units were the same. A 10 meter elevation dataset was used from the USGS National Elevation Dataset (NED) to fill in areas of surrounding States that were necessary to complete river basin areas. The slope values were calculated using ArcGIS slope function.

Land-surface slope influences the amount of precipitation that runs off the land surface or infiltrates into the subsurface.  In general, precipitation is more likely to infiltrate into the subsurface in areas characterized by low slope and run off the land surface in areas characterized by high slope.

In North Carolina, regional slopes range from relatively flat in the Coastal Plain to steep and highly variable in the Piedmont and Blue Ridge Provinces.  There are, however, local exceptions to these regional characterizations.  For example, in the Coastal Plain, slopes may be steep near streams; and in the Piedmont and Blue Ridge Provinces, slopes may be flat in floodplains, valleys, and hilltops. Analysis of a statewide GIS layer depicting land-surface slopes at a resolution of 30-meter grid cells indicates that about 43 percent of the State has slopes of less than 2 percent.  Slightly more than 60 percent of the State has slopes of less than 5 percent.

Slopes were divided into classes and assigned ratings from 1 to 10. Low ratings were assigned to the low slopes, and high ratings were assigned to the high slopes. Surface water is more  vulnerable to contamination in areas where land-surface slope is high.

Land-surface slope categories and ratings for watershed characteristics
rating:

>Land-surface slope,            Percent of area         Rating
>in percent unit rise/unit run      in NC
>
>Less than or equal to               43                    1
>2 percent
>
>Greater than 2 to                   17                    3
>less than or equal to
>5 percent
>
>Greater than 5 to                   16                    5
>less than or equal to
>10 percent
>
>Greater than 10 to                  10                    7
>less than or equal to
>20 percent
>
>Greater than 20 to                  10                    9
>less than or equal to
>50 percent
>
>Greater than 50 percent              3                   10
>NOTE: Due to rounding error, percents may not total 100.
>

SELECTED REFERENCES:

Eimers, J. L., Weaver, J. C., Terziotti, S., and Midgette, R. W.,
2000, Methods of rating unsaturated zone and watershed
characteristics of public water supplies in North Carolina: U. S.
Geological Survey Water-Resources Investigations Report 99-4283,
31 p.

North Carolina Department of Environment and Natural Resources,
1999, North Carolina source water assessment program plan: Raleigh,
North Carolina Department of Environment and Natural Resources,
Division of Environmental Health, Public Water Supply Section,
[variously paged].

U.S. Geological Survey, 1999, National Elevation Dataset Fact Sheet:
accessed January 26, 2001, at URL
http://edcnts12.cr.usgs.gov/ned/factsheet.htm.

DISCLAIMER:

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 ARC/INFO format, this metadata file may include some
ARC/INFO-specific terminology.

*Language of dataset: en

Time period of content:

Time period information:

Single date/time:

Calendar date: 2001

Currentness reference:

ground condition

Status:

Progress: Complete

Maintenance and update frequency: As needed

Spatial domain:

Bounding coordinates:

*West bounding coordinate: -84.907009

*East bounding coordinate: -75.307866

*North bounding coordinate: 37.554514

*South bounding coordinate: 33.052474

Local bounding coordinates:

*Left bounding coordinate: 86676.419070

*Right bounding coordinate: 936216.419070

*Top bounding coordinate: 422155.256040

*Bottom bounding coordinate: -62644.743960

Keywords:

Theme:

Theme keywords: Slope, Elevation, DEM, lidar, Watershed Characteristics, Rating

Theme keyword thesaurus: none

Place:

Place keywords: North Carolina

Place keyword thesaurus: none

Access constraints: none

Use constraints:

These data are not to be used for site-specific analysis

Point of contact:

Contact information:

Contact person primary:

Contact person: Silvia Terziotti

Contact organization: U.S. Geological Survey

Contact position: Computer Specialist

Contact address:

Address type: mailing address

Address:

3916 Sunset Ridge Road

City: Raleigh

State or province: NC

Postal code: 27607

Country: USA

Contact voice telephone: (919) 571-4000

Contact facsimile telephone: (919) 571-4041

Contact electronic mail address: (seterzio@usgs.gov)

Data set credit:

The authors are grateful to colleagues in the Public Water Supply
Section of the Division of Environmental Health, North Carolina
Department of Environment and Natural Resources (DENR) for their
assistance in this collaborative project: thanks to Robert Midgette,
Protection and Enforcement Branch Head; Amy Axon,hydrogeologist - Source Water Protection; and David Hammermann, Geographic Information Systems Specialist.

The authors also thank the USGS report review team for their review of
the update procedures: Jeanne Robbins, Surface-water Specialist; Melinda Chapman, Ground-water Specialist; Mary Giorgino, Water-quality Specialist; and Douglas Harned, ALBE-National Water Quality Assessment Project Chief.

*Native dataset format: Raster Dataset

*Native data set environment:

Microsoft Windows 2000 Version 5.2 (Build 3790) Service Pack 2; ESRI ArcCatalog 9.2.6.1500

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Watershed Characteristics Rating for North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-490

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01490/index.html

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Unsaturated Zone Characteristics Rating for North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-489

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01489/index.html

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Land-Use Classes to Characterize Watersheds and the Unsaturated Zone in North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-493

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01493/index.html

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Land-Cover Classes to Characterize the Unsaturated Zone in North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-491

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01491/index.html

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Percent-Slope Classes to Characterize the Unsaturated Zone in North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-495

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01495/index.html

Cross reference:

Citation information:

Originators: Jo Leslie Eimers, Silvia Terziotti and Gloria Ferrell

Title:

Vertical Series Hydraulic Conductance Classes to Characterize the Unsaturated Zone in North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-486

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01486/index.html

Cross reference:

Citation information:

Originators: Jo Leslie Eimers, Silvia Terziotti and Mary Giorgino

Title:

Estimated Depth to Water, North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-487

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01487/index.html

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Land-Cover Classes to Characterize Watersheds in North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-492

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01492/index.html

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Average Annual Precipitation Classes to Characterize Watersheds in North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-494

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01494/index.html

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Percent-Slope Classes to Characterize Watersheds in North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-496

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01496/index.html

Cross reference:

Citation information:

Originators: Silvia Terziotti and Jo Leslie Eimers

Title:

Ground-Water Contribution Classes to Characterize Watersheds in North Carolina

Publication date: 2001

Geospatial data presentation form: map

Series information:

Series name: USGS Open-File Report

Issue identification: USGS OFR 01-488

Publication information:

Publication place: Raleigh, NC

Publisher: USGS

Online linkage: http://nc.water.usgs.gov/reports/ofr01488/index.html

Data Quality Information:

Attribute accuracy:

Attribute accuracy report:

Slopes and ratings plotted at 1:100,000 scale and visually checked
for accuracy. No field verification was performed. The accuracy
of the ratings is discussed in Eimers and others (2000).

Logical consistency report:

Not applicable for raster data.

Positional accuracy:

Horizontal positional accuracy:

Horizontal positional accuracy report:

30 meter cells: visual spot checks for accuracy

Lineage:

Source information:

Source citation:

Citation information:

Originators: North Carolina Floodplain Mapping Program

Title:

LiDAR

Publication date: 2006

Geospatial data presentation form: map

Series information:

Series name: U.S. Geological Fact Sheet

Issue identification: http://edcnts12.cr.usgs.gov/ned/factsheet.htm

Publication information:

Publication place: Sioux Falls, SD

Publisher: USGS

Online linkage: http://www.ncfloodmaps.com

Source scale denominator: 30 meter

Type of source media: online

Source citation abbreviation:

none

Source contribution:

elevation values

Source time period of content:

Time period information:

Single date/time:

Calendar date: 19990201

Source currentness reference:

Best-available, variously-dated DEM data source

Source information:

Source citation:

Citation information:

Originators: Eimers, J. L., Weaver, J. C., Terziotti, S., Midgette, R. W.

Title:

Methods of rating unsaturated zone and watershed characteristics of public water supplies in North Carolina

Publication date: 2000

Series information:

Series name: U. S. Geological Survey Water-Resources Investigations

Issue identification: WRIR 99-4283

Type of source media: paper

Source citation abbreviation:

Eimers and others (2000)

Source contribution:

methods of applying ratings

Source time period of content:

Time period information:

Single date/time:

Calendar date: 2000

Source currentness reference:

publication date

Process step:

Process description:

Projected LiDAR 20 foot DEMS to StatePlane meters.
Resampled the 20foot DEMS to 30 meters.
Converted the elevation values to meters.
Executed the slope function in Arc/Info GRID to convert the data set to a percent-rise data set.
SLOPE_30M = slope(elev_30m, percentrise)

Process date: 2009

Process step:

Process description:

Remapped the values to the ratings using the
following table (Using the Arc/Info GRID command, SLICE, with
the TABLE option).
>2 : 1
>5 : 3
>10 : 5
>20 : 7
>50 : 9
>1000 : 10

Process date: 20090501

Process step:

Process description:

Metadata imported.

Source used citation abbreviation:

W:\SWAP_updates\Documents\Metadata\slopesw.xml

Spatial Data Organization Information:

*Direct spatial reference method: Raster

Raster object information:

*Image format:

*Number of bands: 1

*Row count: 16160

*Column count: 28318

*Vertical count: 1

*Cell size X direction: 30.000000

*Cell size Y direction: 30.000000

*Bits per pixel: 8

*Pyramid layers: FALSE

*Image colormap: FALSE

*Compression type: Default

*Raster object type: Grid Cell

*Raster display type: matrix values

*Raster origin: Upper Left

Spatial Reference Information:

Horizontal coordinate system definition:

Coordinate system name:

*Projected coordinate system name: NAD_1983_StatePlane_North_Carolina_FIPS_3200

*Geographic coordinate system name: GCS_North_American_1983

Planar:

Grid coordinate system:

*Grid coordinate system name: State Plane Coordinate System 1983

State Plane Coordinate System:

*SPCS zone identifier: 3200

Lambert conformal conic:

*Standard parallel: 34.333333

*Standard parallel: 36.166667

*Longitude of central meridian: -79.000000

*Latitude of projection origin: 33.750000

*False easting: 609601.220000

*False northing: 0.000000

Planar coordinate information:

*Planar coordinate encoding method: row and column

Coordinate representation:

*Abscissa resolution: 30.000000

*Ordinate resolution: 30.000000

*Planar distance units: meters

Geodetic model:

*Horizontal datum name: North American Datum of 1983

*Ellipsoid name: Geodetic Reference System 80

*Semi-major axis: 6378137.000000

*Denominator of flattening ratio: 298.257222

Entity and Attribute Information:

Detailed description:

*Name: slopesw.vat

Entity type:

*Entity type label: slopesw.vat

*Entity type type: Table

*Entity type count: 6

Attribute:

Attribute label: Rowid

Attribute definition:

Internal feature number.

Attribute definition source:

ESRI

Attribute domain values:

Unrepresentable domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute label: VALUE

Attribute:

Attribute label: COUNT

Attribute:

*Attribute label: PCT_TOT

*Attribute alias: PCT_TOT

*Attribute type: Single

*Attribute width: 4

*Attribute precision: 0

*Attribute scale: 0

Attribute:

*Attribute label: SQMI

*Attribute alias: SQMI

*Attribute type: Single

*Attribute width: 4

*Attribute precision: 0

*Attribute scale: 0

Overview description:

Entity and attribute overview:

>
>Value Attribute Table, SLOPESW.VAT:
>
>COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
>    1  VALUE                  4    10     B      -
>    5  COUNT                  4    10     B      -
>    9  PCT_TOT                4     8     F      2
>   13  SQMI                   4     8     F      2
VALUE is the rating: valid values are integers 1, 3, 5, 7, 9, and 10.
COUNT is the number of 30-meter by 30-meter cells in the entire data
set that have the rating.
PCT_TOT is the percent of the total area just of NC within each category.
SQMI is the conversion from 30 meter by 30 meter cells to square miles for NC portion of Study are
>
>  VALUE      COUNT  PCT_TOT     SQMI
>      1  116235497    42.92 23091.79
>      3   65232594    17.09  9197.07
>      5   65979799    15.96  8589.01
>      7   43998285     9.78  5260.34
>      9   41919065     9.57  5151.09
>     10    8721263     2.56  1379.81
>
>Summary Statistics Table, SLOPESW.STA:
>
>COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
>    1  MIN                    8    15     F      3
>    9  MAX                    8    15     F      3
>   17  MEAN                   8    15     F      3
>   25  STDV                   8    15     F      3
>
MIN is the minimum value of item VALUE.
MAX is the maximum value of item VALUE.
MEAN is the average value of item VALUE.
STDV is the standard deviation of item VALUE.
>
>   MIN             MAX            MEAN            STDV
> 1.000          10.000           4.134           2.926

Entity and attribute detail citation:

none

Distribution Information:

Distributor:

Contact information:

Contact organization primary:

Contact organization: U.S. Geological Survey

Contact position: Information Officer

Contact address:

Address type: mailing and physical address

Address:

3916 Sunset Ridge Rd.

City: Raleigh

State or province: NC

Postal code: 27607

Country: USA

Contact voice telephone: (919) 571-4000

Contact electronic mail address: gs-w-ncrlg_www@usgs.gov

Contact instructions:

Contact via email

Resource description: Downloadable Data

Distribution liability:

Although these data have been used by the U.S. Geological Survey,
U.S. Department of the Interior, no warranty expressed or implied
is made by the U.S. Geological Survey as to the accuracy of the
data.

The act of distribution shall not constitute any such warranty,
and no responsibility is assumed by the U.S. Geological Survey in
the use of this data, software, or related materials.

Standard order process:

Digital form:

Digital transfer information:

*Transfer size: 135.036

*Dataset size: 135.036

Metadata Reference Information:

*Metadata date: 20090702

Metadata review date: 2001

*Language of metadata: en

Metadata contact:

Contact information:

Contact organization primary:

Contact person: North Carolina Water Science Center Director

Contact organization: U.S. Geological Survey

Contact position: Director

Contact address:

Address type: mailing and physical address

Address:

3916 Sunset Ridge Road

City: Raleigh

State or province: NC

Postal code: 27607

Country: USA

Contact voice telephone: (919) 571-4000

Contact facsimile telephone: (919) 571-4041

Contact electronic mail address: dc_nc@usgs.gov

*Metadata standard name: FGDC Content Standards for Digital Geospatial Metadata

*Metadata standard version: FGDC-STD-001-1998

*Metadata time convention: local time

Metadata access constraints: none

Metadata use constraints:

none

Metadata extensions:

Online linkage: http://www.esri.com/metadata/esriprof80.html

Profile name: ESRI Metadata Profile

Metadata extensions:

*Online linkage: http://www.esri.com/metadata/esriprof80.html

*Profile name: ESRI Metadata Profile

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URL: https://nc.water.usgs.gov/projects/SWAP/Metadata/slopesw.html
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