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

Open File Report 01-495
By Silvia Terziotti and J.L. Eimers


Project Description

Metadata · Metadata as Plain Text file

Percent slope categories for rating the unsaturated zone

Project Description for Map Data Produced as Part of the North Carolina Source Water Assessment Program


Abstract

This web site contains the Federal Geographic Data Committee-compliant metadata (documentation) for digital data produced for the North Carolina, Department of Environment and Natural Resources, Public Water Supply Section, Source Water Assessment Program. The metadata are for 11 individual Geographic Information System data sets. An overlay and indexing method was used with the data to derive a rating for unsaturated zone and watershed characteristics 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 for susceptibility to contamination. For ground-water supplies, the digital data sets used in the assessment included unsaturated zone rating, vertical series hydraulic conductance, land-surface slope, and land cover. For assessment of public surface-water intakes, the data sets included watershed characteristics rating, average annual precipitation, land-surface slope, land cover, and ground-water contribution. Documentation for the land-use data set applies to both the unsaturated zone and watershed characteristics ratings. Documentation for the estimated depth-to-water map used in the calculation of the vertical series hydraulic conductance also is included.


Abstract || Introduction || Purpose || Contents || Links to Metadata || References

Introduction

Overlay and index methods for rating the unsaturated zone and watershed characteristics 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 for susceptibility to contamination. Factors that influence the vulnerability of public ground water and surface water supplies to contamination were selected and assigned ratings on a scale of 1 to 10, covering the range of values in North Carolina. These factors then were assigned weight to reflect their relative influence on the perceived inherent vulnerability and reliability of the data (Eimers and others, 2000).

Factors selected for rating the vulnerability to contamination of the unsaturated zone are vertical series hydraulic conductance, land-surface slope, land cover, and land use. Vertical series hydraulic conductance measures the capacity of unsaturated material to transmit water. Land-surface slope influences whether precipitation runs off land surfaces or infiltrates into the subsurface. Land cover describes the physical overlay of the land surface, which influences the amount of precipitation that runs off or infiltrates into the subsurface. Land use describes activities occurring on the land surface that influence the potential generation of nonpoint-source contamination.

In order to develop the unsaturated zone vulnerability rating, an estimated depth-to-water map was created. The estimated depth-to-water map was necessary for the calculation of the vertical series hydraulic conductance values. A documentation file was created describing methods and formulas that were applied to generate this data set.

Factors selected for rating the watershed characteristics upstream from surface-water intakes are average annual precipitation, land-surface slope, land cover, land use, and ground-water contribution. The average annual precipitation represents the amount of water available for transport in a watershed. Land-surface slope, land cover, and land use have similar influences on watershed characteristics as those identified for the unsaturated zone. Ground-water contribution represents the part of streamflow that is derived from ground water.

The values for each factor were obtained from Geographic Information System (GIS) data layers stored as raster data sets. These raster data sets have 30-meter by 30-meter cells, and each cell is assigned a value based on the characteristics of the factor within that cell. Only one data set was created for the land-use factor because identical ratings were applied for the unsaturated zone rating and watershed characteristics rating. The values for each factor were assigned a weight, then the weighted values were combined to create the final vulnerability values for the unsaturated zone and watershed characteristics ratings.

A structured documentation file (known as "metadata") for each data set has been created. The documentation files comply with the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (Federal Geographic Data Committee, 1994). The FGDC-compliant metadata files contain descriptions of the data sets and include narrative sections describing the procedures used to produce the data sets in digital form. The metadata also include references of the sources used to create the data set.


Abstract || Introduction || Purpose || Contents || Links to Metadata || References

Purpose

This page provides background context for the 11 digital data sets created for the North Carolina Source Water Assessment Program (SWAP), and is the access point for all associated metadata files.


Abstract || Introduction || Purpose || Contents || Links to Metadata || References

Contents

The FGDC-compliant metadata for the 11 data sets are linked below. The digital data are not currently online because of space limitations. The digital data sets can be requested through the distribution contact identified in the metadata.


Abstract || Introduction || Purpose || Contents || Links to Metadata || References

Links to metadata

Links to jpeg images
of the data sets

Unsaturated Zone Characteristics Rating for North Carolina (OFR 01-489) Inherent vulnerability categories for rating the unsaturated zone
Percent-Slope Classes to Characterize the Unsaturated Zone in North Carolina (OFR 01-495) Percent slope categories for rating the unsaturated zone
Land-Cover Classes to Characterize the Unsaturated Zone in North Carolina (OFR 01-491) Landcover categories for rating the unsaturated zone
Vertical Series Hydraulic Conductance Classes to Characterize the Unsaturated Zone in North Carolina (OFR 01-486) Vertical hydraulic conductance categories for rating the unsaturated zone
Estimated Depth to Water, North Carolina (OFR 01-487) Depth to water
Land-Use Classes to Characterize Watersheds and the Unsaturated Zone in North Carolina (OFR 01-493) Landuse categories for rating the unsaturated zone and watershed characteristics
Watershed Characteristics Rating for North Carolina (OFR 01-490) Inherent vulnerability categories for rating watershed characteristics
Land-Cover Classes to Characterize Watersheds in North Carolina (OFR 01-492) Landcover categories for rating watershed characteristics
Average Annual Precipitation Classes to Characterize Watersheds in North Carolina (OFR 01-494) Average annual precipitation categories
Percent-Slope Classes to Characterize Watersheds in North Carolina (OFR 01-496) Percent slope categories for rating watershed characteristics
Ground-Water Contribution Classes to Characterize Watersheds in North Carolina (OFR 01-488) Ground-water contribution categories

Abstract || Introduction || Purpose || Contents || Links to Metadata || References

References

Eimers, J.L., Weaver, J.C., Terziotti, Silvia, 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.

Federal Geographic Data Committee, 1994, Content standards for digital geospatial metadata (June 8): Washington, D.C., Federal Geographic Data Committee, 78 p.



USGS home page

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

Open File Report 01-495
By Silvia Terziotti and J.L. Eimers

Metadata

Metadata is also available as a Plain Text file.


Identification_Information:

Citation:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers, USGS
Publication_Date: 1999
Title: Percent-Slope Classes to Characterize the Unsaturated Zone in North Carolina
Edition: Version 1.0, January 26, 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: U.S. Geological Survey

Description:

Abstract:

Percent-slope classes to characterize the unsaturated zone is one of 11 data sets developed for the North Carolina Source Water Assessment Program. These data are used to rate the susceptibility of public water supplies in North Carolina to contamination.

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 ground-water systems, the greater the likelihood that water will infiltrate the land surface (that is, the lower 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 Federal Safe Drinking Water Act (SDWA) Amendments of 1996 emphasize pollution prevention as an important strategy for the protection of ground-water and surface-water resources. This new focus in the SDWA promotes the prevention of drinking water contamination as a cost-effective means of ensuring reliable, long-term, and safe drinking water sources for public water-supply systems (North Carolina Department of Environment and Natural Resources, 1999a). Specifically, Section 1453 of the SDWA Amendments requires that States develop and implement a Source Water Assessment Program (SWAP) to delineate source water areas, inventory potential contaminants in these areas, and determine the susceptibility of each public water supply to contamination. The agency charged with the task of susceptibility assessment in North Carolina is the Public Water Supply Section (PWSS) of the Department of Environment and Natural Resources. The U.S. Geological Survey (USGS) is directed under the Clean Water Action Plan, funded by Congress in 1999, to assist States with water-quality monitoring and susceptibility determinations.

The inherent vulnerability rating is a measure of the potential for contaminants within a delineated source area to reach the ground-water or surface-water supply. The inherent vulnerability of a ground-water source of public water supply is determined by combining an aquifer rating and an unsaturated zone rating (North Carolina Department of Environment and Natural Resources, 1999a). The inherent vulnerability of a surface-water source of public water supply is determined by combining a watershed classification, intake location, raw water quality (water plant data), North Carolina Division of Water Quality Use Support rating, and watershed characteristics rating (North Carolina Department of Environment and Natural Resources, 1999a). In cooperation with the PWSS, the USGS developed methods to rate unsaturated zones for public ground-water systems and watershed characteristics for public surface-water intakes. All other components of inherent vulnerability were compiled by the PWSS.

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.

The identification of factors, development of ratings for each, and subsequent assignment of weights were based on (1) a literature search, which included examination of potential factors and their effects on the drinking-water quality; and (2) consultation with experts in the fields of hydrology, geology, forestry, agriculture, and water management. The relative rating of the unsaturated zone and watershed characteristics combines hydrologic data with expert knowledge to assess the vulnerability of water supplies to contamination.

Factors selected for rating the inherent vulnerability of the unsaturated zone to contamination are vertical series hydraulic conductance, land-surface slope, land cover, and land use. Vertical series hydraulic conductance measures the capacity of the unsaturated material to transmit water. Land-surface slope influences whether precipitation runs off land surfaces or infiltrates into the subsurface. Land cover describes the physical overlay of the land surface, which influences the amount of precipitation that runs off or infiltrates into the subsurface. Land use describes activities occurring on the land surface that influence the potential generation of nonpoint-source contamination.

Factors selected for rating vulnerability to contamination of the watershed upstream from surface-water intakes are average annual precipitation, land-surface slope, land cover, land use, and ground-water contribution. The average annual precipitation represents the mass of water that becomes available for transport in a watershed. Land-surface slope, land cover, and land use have similar influences on watershed characteristics as those identified for the unsaturated zone. In the cases of land-surface slope and land cover, the ratings for watershed characteristic vulnerability are the opposite of unsaturated zone vulnerability to contamination (i.e. more infiltration or ponding produces a higher vulnerability to ground-water, but less to surface-water sources.) Ground-water contribution represents the part of streamflow that is derived from ground-water discharge.

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:

The elevation data set used to derive the slope components was the National Elevation Dataset (NED) developed by the USGS Eros Data Center. The NED is designed to provide national elevation data in a seamless form with a consistent datum, elevation unit, and map projection (USGS, 1999).

The NED is a mosaic of the best-available elevation data from the USGS. The 7.5-minute-quadrangle elevation data for the conterminous United States are the initial source data. In addition to using best-available 7.5-minute data, processing methods were developed to filter production artifacts from the data, convert datum to NAD83 datum, edge-match, and fill slivers of missing data at quadrangle seams. These processes produce a much-improved base of elevation data for calculating slope and hydrologic derivatives.

The complete metadata on the NED can be found at: http://edcnts12.cr.usgs.gov/ned/fgdcmetadata.htm
URL updated June 23 2005: http://ned.usgs.gov/Ned/metadata.asp

SLOPE:

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 60-meter grid cells indicates that nearly 47 percent of the State has slopes of less than 2 percent. Slightly more than 80 percent of the State has slopes of less than 10 percent.

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

Land-surface slope categories and ratings for unsaturated zone rating:

Land-surface slope,            Percent of area         Rating
in percent unit rise/unit run      in NC

Greater than 50 percent            2                      1

Greater than 20 to                 9                      3
less than or equal to
50 percent

Greater than 10 to                 9                      5
less than or equal to
20 percent

Greater than 5 to                 16                      7
less than or equal to
10 percent

Greater than 2 to                 18                      9
less than or equal to
5 percent

Less than or equal to             47                     10
2 percent
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.
URL updated June 23 2005: http://erg.usgs.gov/isb/pubs/factsheets/fs14899.html

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.

Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1980
Currentness_Reference: Ground Condition

Status:
Progress: complete
Maintenance_and_Update_Frequency: As Needed

Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -84.90706954
East_Bounding_Coordinate: -75.16688733
North_Bounding_Coordinate: 37.49637014
South_Bounding_Coordinate: 33.05247366

Keywords:
Theme:
Theme_Keyword_Thesaurus: none
Theme_Keyword: Slope
Theme_Keyword: Elevation
Theme_Keyword: DEM
Theme_Keyword: Hypsography
Theme_Keyword: Unsaturated Zone
Theme_Keyword: Rating
Place:
Place_Keyword_Thesaurus: none
Place_Keyword: North Carolina

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; Elizabeth Morey, Hydrogeologist; Gale Johnson, Hydrogeologist; and Rajpreet Butalia, Geographic Information Systems Specialist.

The authors also thank the following scientists and engineers who provided additional technical review of this work:

Richard Burns, Watershed and Forest Hydrologist, U.S. Forest Service,
U.S. Department of Agriculture
Ron Coble, Professional Geologist [Retired USGS]
Ed Holland, Orange County Water and Sewer Authority
Beth McGee, Clean Water Management Trust Fund
Ted Mew, Groundwater Section, Division of Water Quality, North
Carolina DENR
Joe Rudek, Environmental Defense Fund
Henry Wade, Pesticides Section, North Carolina Department of
Agriculture
Steve Zoufaly, Division of Water Quality, North Carolina DENR

The authors also thank the USGS report review team for their review of the metadata products: Stephen J. Char, Jason M. Fine, Michael L. Strobel, Douglas A. Harned and Rebecca J. Deckard.

Native_Data_Set_Environment:
Windows_NT, 5.0, Intel
ARC/INFO version 8.0.2

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Watershed Characteristics Rating for North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Unsaturated Zone Characteristics Rating for North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Land-Use Classes to Characterize Watersheds and the Unsaturated Zone in North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Land-Cover Classes to Characterize the Unsaturated Zone in North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Percent-Slope Classes to Characterize the Unsaturated Zone in North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Jo Leslie Eimers, Silvia Terziotti and Gloria Ferrell
Publication_Date: 2001
Title: Vertical Series Hydraulic Conductance Classes to Characterize the Unsaturated Zone in North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Jo Leslie Eimers, Silvia Terziotti and Mary Giorgino
Publication_Date: 2001
Title: Estimated Depth to Water, North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Land-Cover Classes to Characterize Watersheds in North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Average Annual Precipitation Classes to Characterize Watersheds in North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Percent-Slope Classes to Characterize Watersheds in North Carolina
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

Cross_Reference:
Citation_Information:
Originator: Silvia Terziotti and Jo Leslie Eimers
Publication_Date: 2001
Title: Ground-Water Contribution Classes to Characterize Watersheds in North Carolina
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


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.

Completeness_Report:
Water features not depicted on a 7.5 minute quadrangle are not reflected in the source elevation data set. For example, slopes where there are now reservoirs reflect the centerline of the lake bottom, i.e. flat lake areas were not created where they were not present in the source NED 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:
Originator: USGS
Title: National Elevation Dataset
Publication_Date: 1999
Geospatial_Data_Presentation_Form: map
Publication_Information:
Publication_Place: Sioux Falls, SD
Publisher: USGS
Series_Information:
Series_Name: U.S. Geological Fact Sheet
Issue_Identification: http://edcnts12.cr.usgs.gov/ned/factsheet.htm
URL updated June 23 2005: http://erg.usgs.gov/isb/pubs/factsheets/fs14899.html
Source_Scale_Denominator: 30 meter
Type_of_Source_Media: online
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_Citation_Abbreviation: none
Source_Contribution: elevation values

Source_Information:
Source_Citation:
Citation_Information:
Originator: Eimers, J. L.
Originator: Weaver, J. C.
Originator: Terziotti, S.
Originator: 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_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 2000
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: Eimers and others (2000)
Source_Contribution: methods of applying ratings

Process_Step:
Process_Description:
Executed the slope function in Arc/Info GRID to convert the NED data set to a percent-rise data set.
SLOPE_30M = slope(elev_30m, percentrise)
Process_Date: 20001030

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 : 10
5 : 9
10 : 7
20 : 5
50 : 3
1000 : 1
Process_Date: 20010126

Process_Step:
Process_Description:
First draft of metadata created by seterzio using FGDCMETA.AML ver. 1.31 10/16/98 on ARC/INFO data set g:\gw_layers\slopegw
Process_Date: 20010126


Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Grid Cell
Row_Count: 16163
Column_Count: 28734


Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: State Plane Coordinate System 1983
State_Plane_Coordinate_System:
SPCS_Zone_Identifier: 4901
Lambert_Conformal_Conic:
Standard_Parallel: 34.333
Standard_Parallel: 36.167
Longitude_of_Central_Meridian: 79.000
Latitude_of_Projection_Origin: 33.750
False_Easting: 2000000
False_Northing: 0.000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 30.0
Ordinate_Resolution: 30.0
Planar_Distance_Units: Meters
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: GRS1980
Semi-major_Axis: 6378206.4
Denominator_of_Flattening_Ratio: 294.98


Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Value Attribute Table, SLOPEGW.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 within each category.
SQMI is the conversion from 30 meter by 30 meter cells to square miles.
VALUE      COUNT  PCT_TOT     SQMI
1    7813391     2.07  2715.08
3   42293996    11.20 14696.75
5   44442845    11.77 15443.46
7   66687677    17.67 23173.32
9   64395933    17.06 22376.96
10  151861198    40.23 52770.29

Summary Statistics Table, SLOPEGW.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           7.740           2.601
Entity_and_Attribute_Detail_Citation: none


Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Position: Water Webserver Team
Contact_Address:
Address_Type: mailing and physical address
Address: 12201 Sunrise Valley Drive, MS 440
City: Reston
State_or_Province: VA
Postal_Code: 20192
Country: USA
Contact_Voice_Telephone: (800) 426-9000
Contact_Instructions: Contact via email
Contact_Electronic_Mail_Address: h2oteam@usgs.gov

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.


Metadata_Reference_Information:
Metadata_Date: 20010209
Metadata_Review_Date: 2001
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: North Carolina District Chief
Contact_Position: District Chief
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
("CSDGM version 2")
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Access_Constraints: none
Metadata_Use_Constraints: none

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