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[an error occurred while processing this directive]landusesw | |
Data format: Raster Dataset File or table name: landusesw Coordinate system: State Plane Coordinate System 1983 Theme keywords: Land cover2009, MRLC, Vulnerability, Unsaturated zone, Watershed |
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Abstract:
Land-use classes to characterize watersheds and the unsaturated zone
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-use classes
for use in the rating of the unsaturated zone for public ground-water
suppliers and in the rating of the watershed characteristics for
surface-water suppliers. The same ratings apply for unsaturated zone
and watershed characteristics.
The ratings relate to the likelihood of potential nonpoint-source
contamination for a given land use. For the ground and surface-water
systems, the greater the likelihood that nonpoint source contamination
exists, the higher the rating on a scale of 1 to 10. |
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.
Land-use classes to characterize watersheds and the unsaturated zone 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-use classes for use in the rating of the unsaturated zone for public ground-water suppliers and in the rating of the watershed characteristics for surface-water suppliers. The same ratings apply for unsaturated zone and watershed characteristics. The ratings relate to the likelihood of potential nonpoint-source contamination for a given land use. For the ground and surface-water systems, the greater the likelihood that nonpoint source contamination exists, the higher the rating on a scale of 1 to 10.
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.
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. LAND USE: The main objective of the Multi-Resolution Land Characteristics (MRLC) consortium is to generate a generalized and consistent land cover data layer for the entire conterminous United States (Bara, 1994). The first release of a National land cover product was in 1992. The Multi-Resolution Land Characteristics (MRLC) data used in 1999 was the NLCD 1992 data product. The source of land cover for this update is the National Land Cover Dataset (NLCD) 2001 land cover product. The 2001 data was released over a multi-year period, beginning in about 2004 for North Carolina. Slight changes were made to the land cover classes for the NLCD 2001 data. The USGS has published a cross-walk to allow users of the 1992 data to match categories in the 2001 data. A table is provided from the NLCD 1992-2001 Retrofit Change Product website to aid is comparing the 1992 product with the 2001 product (http://www.mrlc.gov/changeproduct.php). A great deal of care was taken when assigning values to the land cover classes in the original project. A team of experts were used to come up with assigned ratings for each land cover class. The scope of this update effort did not allow the time to reassemble a team of outside experts to assign values to new classes in the land cover data set. An internal review team of specialists were assembled at the USGS to review the land cover classes and assign rating values to the new classes. The team was comprised of USGS, N.C. Water Science Center employees including the N.C. Water Quality Specialist, N.C. Surface Water Specialist, N.C. Groundwater Specialist, Albermarle-Pamlico Basin National Water-Quality Assessment Study Unit Chief, Hydrologic Investigations Section Chief, and the N.C. Geographic Information Systems Specialist. Team members reviewed the definitions of new classes and reviewed the cross-walk from the 1992 to 2001 data set to assign final ratings to all classes of the 2001 NLCD land cover data for the unsaturated zone, watershed characteristics and land use. For the study, the map projection of the land-cover data was changed from the original Albers conical equal area coordinate system into the North Carolina State Plane system, North American Datum 83, map units of meters, and aligned to match the lower-left corner of the other contributing-factor data sets. Because the MRLC data are categorical, a nearest-neighbor algorithm was used to resample cell values from one coordinate system to the next, thus preserving the spatial accuracy of the classification scheme. The source of data for the land-use factor is identical to the source of data for land cover, both of which are derived from the same land-cover GIS layer (MRLC land-cover data). Although land-use and land-cover categories use the same data source and terminology, they are considered separate factors in the unsaturated zone ratings. The land-use factor measures the potential for generating nonpoint- source contamination at land surface; the land-cover factor influences the amount of precipitation that infiltrates the ground. These factors are treated separately to highlight the influence of nonpoint-source contaminants in the unsaturated zone rating. Land use describes activities that occur on the land surface and influence the potential generation of nonpoint-source contamination from these activities. The effect of land use on water quality has been the subject of previous data-collection and interpretive investigations (Eckhardt and Stackelberg, 1995; Corwin and others, 1997). Of particular note is a series of water-quality studies in large river basins across the United States conducted by the USGS as part of the National Water-Quality Assessment Program (NAWQA), which began in 1991. Other investigations have focused on study areas having one predominant land use, such as effects of agricultural lands on water quality (Nolan and Clark, 1997). Ratings assigned to land-use categories reflect the vulnerability of water supplies to nonpoint-source contamination. Land-use categories and ratings for unsaturated zone and watershed characteristics ratings: >NLCD code - Class Description Percent of Land Use UZR > area in NC and WSC Rating >11. Open Water - All areas of open water, generally with less >than 25% cover of vegetation or soil. 1 1 > >90. Woody Wetlands - Areas where forest or shrubland vegetation 11 1 >accounts for greater than 20 percent of vegetative cover and the >soil or substrate is periodically saturated with or covered with water. > >95. Emergent Herbaceous Wetlands - Areas where perennial herbaceous 1 1 >vegetation accounts for greater than 80 percent of vegetative cover >and the soil or substrate is periodically saturated with or covered >with water. > >31. Barren Land (Rock/Sand/Clay) - Barren areas of bedrock, desert < 1 2 >pavement, scarps, talus, slides, volcanic material, glacial debris, >sand dunes, strip mines, gravel pits and other accumulations of >earthen material. Generally, vegetation accounts for Less than >15% of total cover. > >41. Deciduous Forest - Areas dominated by trees generally greater 28 3 >than 5 meters tall, and greater than 20% of total vegetation cover. >More than 75 percent of the tree species shed foliage simultaneously >in response to seasonal change. > >42. Evergreen Forest - Areas dominated by trees generally greater 14 3 >than 5 meters tall, and greater than 20% of total vegetation cover. >More than 75 percent of the tree species maintain their leaves all >year. Canopy is never without green foliage. > >43. Mixed Forest - Areas dominated by trees generally greater than 3 3 >5 meters tall, and greater than 20% of total vegetation cover. >Neither deciduous nor evergreen species are greater than 75 >percent of total tree cover. > >52. Shrub/Scrub - Areas dominated by shrubs; less than 5 meters 2 4 >tall with shrub canopy typically greater than 20% of total vegetation. >This class includes true shrubs, young trees in an early successional >stage or trees stunted from environmental conditions. > >71. Grassland/Herbaceous - Areas dominated by grammanoid or 6 4 >herbaceous vegetation, generally greater than 80% of total >vegetation. These areas are not subject to intensive management >such as tilling, but can be utilized for grazing. > >81. Pasture/Hay - Areas of grasses, legumes, or grass-legume 12 5 >mixtures planted for livestock grazing or the production of seed >or hay crops, typically on a perennial cycle. Pasture/hay vegetation >accounts for greater than 20 percent of total vegetation. > >21. Developed, Open Space - Includes areas with a mixture of some 6 6 >constructed materials, but mostly vegetation in the form of lawn >grasses. Impervious surfaces account for less than 20 percent of >total cover. These areas most commonly include large-lot single- >family housing units, parks, golf courses, and vegetation planted >in developed settings for recreation, erosion control, or aesthetic purposes > >22. Developed, Low Intensity - Includes areas with a mixture of 2 7 >constructed materials and vegetation. Impervious surfaces account >for 20-49 percent of total cover. These areas most commonly include >single-family housing units. > >82. Cultivated Crops - Areas used for the production of annual 11 7 >crops, such as corn, soybeans, vegetables, tobacco, and cotton, >and also perennial woody crops such as orchards and vineyards. >Crop vegetation accounts for greater than 20 percent of total >vegetation. This class also includes all land being actively tilled. > >23. Developed, Medium Intensity - Includes areas with a mixture of 1 8 >constructed materials and vegetation. Impervious surfaces account >for 50-79 percent of the total cover. These areas most commonly >include single-family housing units. > >24. Developed, High Intensity - Includes highly developed areas < 1 10 >where people reside or work in high numbers. Examples include >apartment complexes, row houses and commercial/industrial. Impervious >surfaces account for 80 to100 percent of the total cover. SELECTED REFERENCES: Bara, T.J., comp., ed., 1994, Multi-resolution land characteristics consortium--documentation notebook, [Environmental Monitoring and Assessment Program-Landscape Characterization, Contract 68-DO-0106]: Research Triangle Park, N.C., ManTech Environmental Technology, Inc. [variously paged]. Corwin, D.L., Vaughn, P.J., and Loague, K., 1997, Modeling nonpoint source pollutants in the vadose zone with GIS: Environmental Science and Technology, v. 31, no. 8, p. 2157-2174. Eckhardt, D.A., and Stackelberg, P.E., 1995, Relation of ground-water quality to land use on Long Island, New York: Ground Water, v. 33, no. 6, p. 1019-1033. 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. Nolan, B.T., and Clark, M.L., 1997, Selenium in irrigated agricultural areas of the western United States: Journal of Environmental Quality, v. 26, no. 3, p. 849-857. 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]. For more information on MRLC data please see: http://www.epa.gov/mrlc/ or http://gisdata.usgs.gov 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.
TM imagery 1998-2001
These data are not to be used for site-specific analysis
3916 Sunset Ridge Road
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
The accuracy of the ratings are based on expert opinion. No field verification of source land-cover classes was performed for this project.
Not applicable for raster data.
MRLC data was processed in 5/2000. An updated version of the data is now available.
based on 30 meter data - accuracy checks not performed by Raleigh office
land-cover classes
land-cover classes and definitions
methods for deriving classes
Mosaicked portions of the MRLC data from GA, SC, TN and VA into the NC data (use Arc/Info GRID command MERGE) set so that an overlapping area covering contributing basins
Used the spatial analyst reclass command to create categories from 1 to 10 based on the land cover classes and their assigned rating
Metadata imported.
Internal feature number.
ESRI
> >Value Attribute Table, LANDUSEGW.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, 2, 3, 5, 6, 7, 8, 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 NC for each of the classes. SQMI is the conversion from 30 meter by 30 meter cells to square miles for study area within NC. > VALUE COUNT PCT_TOT SQMI > 1 56836045 20.61 11087.49 > 2 2013428 0.41 218.94 > 3 180955325 41.61 22388.77 > 4 27729490 7.53 4050.88 > 5 48914641 10.77 5794.45 > 6 21761297 5.83 3136.59 > 7 34427299 12.42 6682.07 > 8 2658908 0.61 326.94 > 10 1051190 0.22 119.14 >Summary Statistics Table, LANDUSEGW.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 3.620 1.765 >
none
3916 Sunset Ridge Rd.
Contact via email
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.
3916 Sunset Ridge Road