Metadata: 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01495/index.html 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 unsat- urated 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 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. 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01490/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01489/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01493/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01491/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01495/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01486/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01487/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01492/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01494/index.html 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 Online_Linkage: http://nc.water.usgs.gov/reports/ofr01496/index.html 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 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. 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 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