Kerie J. Hitt 2008 Version 3, March 2006 (Supersedes NLCDep0905, Version 2, Sept 2005) 30-meter raster digital data Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?nlcdep0306 This 30-meter resolution raster data set of land cover for the conterminous United States ("NLCDep0306") was designed to describe conditions representative of the year 2000 and is the result of overlaying enhanced 1992 National Land Cover Data with 1990 and 2000 population data at the block group geographic level. Any area (excluding water, developed land, or wetlands) with population density of less than 1,000 people per square mile in 1990 and at least 1,000 people per square mile in 2000 was reclassified as "newly urbanized" land in the derivative product. Areas of water, developed land, or wetlands existing in the original national land-cover data set were preserved. This data set supersedes the one called "Enhanced National Land Cover Data 1992 revised with 2000 population data to indicate urban development between 1992 and 2000" ("NLCDep0905") dated September 2005. NLCDep0905 coded any area having 2000 population density of at least 1,000 people per square mile as being recently urbanized and did not consider that the area could already have been urbanized in 1990. The approach used in developing NLCDep0905 was determined to have misclassified lands that already were urban in 1990 as newly urbanized and therefore overrepresented new urban land. The U.S. Geological Survey's (USGS) National Water-Quality Assessment (NAWQA) Program uses nationally consistent land cover to characterize environmental settings of stream and ground-water sampling sites. NAWQA uses areal weighting with mapped land cover to refine the spatial distribution of various quantitative data, especially nutrient inputs and pesticide applications, which originally are compiled by county. In 2005, NAWQA required nationally consistent land-cover data representing the early 2000s to indicate changes in urban/suburban land since the 1990s and to spatially allocate nutrient and pesticide data derived using the 2002 Census of Agriculture. The NLCDep0306 data set was compiled from data sources existing at that time as a stopgap measure to describe land cover in the early 2000s for NAWQA stream sampling sites until the USGS National Land Cover Database (NLCD) 2001 became available nationwide. DATA STRUCTURE: The data is stored in four tiles, one for each of the quadrants of the conterminous United States: NLCDep0306_1 (northwest quadrant of the United States) NLCDep0306_2 (northeast quadrant) NLCDep0306_3 (southwest quadrant) NLCDep0306_4 (southeast quadrant). Each quadrant has two digital files, named as follows (where x = 1,2,3, or 4): nlcdep0306_x.tif--GeoTIFF (georeferenced Tag Image Format File) raster file of data nlcdep0306_x.tfw--GeoTIFF "World File" containing the following information for registering the image: >line 1: x resolution >line 2: amount of translation >line 3: amount of rotation >line 4: negative of the y resolution >line 5: x ground coordinate of center of upper left pixel >line 6: y ground coordinate of center of upper left pixel Example world file for quadrant 3: >line 1: 30.00000000000000 >line 2: 0.00000000000000 >line 3: 0.00000000000000 >line 4: -30.00000000000000 >line 5: -2379990.00000000000000 >line 6: 1874970.00000000000000 BACKGROUND: The National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS) assesses the quality of streams, ground water, and aquatic ecosystems across the Nation (Hamilton and others, 2004). The NAWQA Program requires nationally consistent land-cover data to characterize environmental settings of stream and ground-water sampling sites. The primary source for mapped land cover during the first decade of sampling by NAWQA (1991-2001) was "enhanced National Land Cover Data 1992" ("NLCDe 92") (Nakagaki and others, 2007). The NLCDe 92 was based primarily on 1992 National Land Cover Data ("NLCD 92") derived from satellite imagery (U.S. Geological Survey, 1999). Nakagaki and others (2007) produced NLCDe 92 by reclassifying NLCD 92 using enhanced historical Land Use and Land Cover (LULC) (Price and others, 2007). The LULC data set originally was derived from aerial photographs and better represents certain land cover categories that are not well-depicted by satellite imagery (Residential; Orchards, Groves, Vineyards, Nurseries, and Ornamental Horticultural Areas; and Tundra.) As water-quality sampling by the NAWQA Program progressed into a second decade, a data set of land cover more up to date than 1992 was required, particularly to determine where land had changed to suburban/urban since that year and to better match the time period of quantitative data on agricultural chemical use derived from the 2002 Census of Agriculture (U.S. Department of Agriculture, 2004). NLCD 2001 (Homer, 2004) was not available nationwide at this time (2005). The strategy to fill the requirement for 2000 land use was to refine NLCDe 92 using 1990 and 2000 population density to indicate urban areas. The approach was similar to that of Hitt (1994), which refined 1970s land use data with 1990 population to indicate urban land representative of the 1990s. Hitt (1994) set the threshold for urban land at 1,000 people per square mile in accordance with how the U.S. Bureau of the Census defined "Urbanized Areas" (U.S. Department of Commerce, Bureau of the Census, 1996). The same cutoff was used in developing NLCDep0306. The assumptions for combining NLCDe 92 with 1990 and 2000 population data to indicate recent (early 2000s) urban development were: 1) Most arable land in the United States already is cultivated, so we assumed a negligible increase in agricultural land from 1992-2000. 2) The largest category of land use change from 1992 to 2000 would be conversion of agricultural land to suburban and urban land. 3) The increase in suburban and urban land could be approximated by the increase in population from 1990 to 2000. The NLCDep0306 data set was created by reclassifying NLCDe 92 using 1990 and 2000 population density by Census block group. Using population by block group overrepresents urbanized areas, but spatial data at the more detailed block level were not practical for processing at the resolution required. Generalized boundaries of the 1990 and 2000 Census block groups (U.S. Bureau of the Census, Geography Division, 1990 and 2001a) were converted to grids with a 30-meter resolution to correspond with the 30-meter raster national land cover data. Each block group had an associated 1990 or 2000 population density calculated from the respective Census of population (U.S. Bureau of the Census, 1991; Geolytics, 2001) as population of the block group divided by land area of the block group. The 30-meter block group boundaries were overlaid with the 30-meter resolution NLCDe 92 land cover. The decision rules for reclassifying land cover in the 30-meter resolution combined land-cover/population grid follow: 1) Existing NLCDe 92 water, developed land, and wetlands were preserved. Recently urbanized land is defined as land areas that were NOT considered "urban" in 1990 but ARE considered "urban" in 2000 according to the population density cut off of 1,000 people per square mile (386 people per square kilometer). 2) Any 30-meter grid cell in NLCDe 92 that is not any of these categories: WATER-- Open Water DEVELOPED LAND-- Low Intensity Residential, High Intensity Residential, Commercial/Industrial/Transportation, LULC Residential, NLCD/LULC Forested Residential, Urban/Recreational Grasses WETLANDS-- Woody Wetlands, Emergent Herbaceous Wetlands FOREST-- Deciduous Forest, Evergreen Forest, Mixed Forest was reclassified as "Newly Urbanized Without Trees" in NLCDep0306 if the same 30x30-meter areas in the population density grids have 1990 population density of less than 1,000 people per square mile and 2000 population density of at least 1,000 people per square mile or more. 3) Any 30-meter grid cell in the NLCDe 92 that is any of these categories: FOREST-- Deciduous Forest, Evergreen Forest, Mixed Forest was reclassified as "Newly Urbanized With Trees" in NLCDep0306 if the corresponding 30x30-meter areas in the population density grids have 1990 population density of less than 1,000 people per square mile and 2000 population density of at least 1,000 people per square mile or more. 4) Any 30-meter grid cell in NLCDe 92 regardless of land cover was NOT changed if the same 30x30-meter area in the 2000 population grid has population density of less than 1,000 people per square mile (area does not meet "urban" criteria for 2000) or if the same area in the 1990 population grid has population density of 1,000 people per square mile or more (area considered to be urban already by 1990). After the land cover and population were overlaid, the resulting data set was clipped to the county boundaries and shoreline of the conterminous United States. Clipping to the county/shoreline grid provided consistency for areal weighting of county-based attributes, such as nutrient inputs, pesticide applications, and other agricultural variables, to selected land cover classes. The 30-meter resolution clipping grid was derived by Jo Ann Gronberg (USGS, written commun., 2005) from 2001 county boundaries and a medium resolution coastline (National Oceanic and Atmospheric Administration, 1994). The 1990 county boundaries from 1:100,000-scale TIGER/Line data (U.S. Department of Commerce, Bureau of the Census, 1993) were the base for the 2001 county boundaries for consistency with the county boundaries used with NLCDe 92. The 1990 county boundaries and codes were updated for changes between 1990 and 2000 using 2000 (U.S. Bureau of the Census, Geography Division, 2001b) and 2004 (U.S. Bureau of the Census, Geography Division, 2005) TIGER/Line files. The extents of valid data in the county/shoreline grid and the land-cover grid differed slightly. When overlaying these grids, the following applied: 1) Any grid cell in the land-cover grid that extended beyond the extent of the boundaries depicted by the county/shoreline grid was removed from the final NLCDep0306. These mostly were cells coded as "Open Water." Cells with valid county codes were not removed. 2) Any grid cell with a valid county code in the county/shoreline grid but with no land-cover code was coded as "Missing Data" in the final NLCDep0306. NLCDep0306 contains the following land-cover classifications, including 25 categories from NLCDe 92, 2 new categories added to indicate newly urbanized land (indicated by *), and 1 category for "Missing Data." The full definitions follow the table. > NLCDep0306 Land-Cover Classes >(modified from NLCD and NLCDe 92 classifications) > > * indicates a new class created by overlaying NLCDe 92 and > 1990 and 2000 population density data. > > CODE Land-Cover Classification Source of Definition > ----- ------------------------------------------------------- > 0 No Data (outside of conterminous U.S.) NLCDe 92,NLCDep > 11 Open Water NLCD 92 > 12 Perennial Ice/Snow NLCD 92 > 21 Low Intensity Residential NLCD 92 > 22 High Intensity Residential NLCD 92 > 23 Commercial/Industrial/Transportation NLCD 92 > 25 LULC Residential NLCDe 92 > 26 NLCD/LULC Forested Residential NLCDe 92 > * 27 Newly Urbanized Without Trees NLCDep > * 28 Newly Urbanized With Trees NLCDep > 31 Bare Rock/Sand/Clay NLCD 92 > 32 Quarries/Strip Mines/Gravel Pits NLCD 92 > 33 Transitional NLCD 92 > 41 Deciduous Forest NLCD 92 > 42 Evergreen Forest NLCD 92 > 43 Mixed Forest NLCD 92 > 51 Shrubland NLCD 92 > 61 Orchards/Vineyards/Other NLCD 92 > 62 LULC Orchards/Vineyards NLCDe 92 > 71 Grasslands/Herbaceous NLCD 92 > 72 LULC Tundra NLCDe 92 > 81 Pasture/Hay NLCD 92 > 82 Row Crops NLCD 92 > 83 Small Grains NLCD 92 > 84 Fallow NLCD 92 > 85 Urban/Recreational Grasses NLCD 92 > 91 Woody Wetlands NLCD 92 > 92 Emergent Herbaceous Wetlands NLCD 92 > 99 Missing Data NLCDe 92,NLCDep NLCDep0306 Classifications: Below are the NLCDep0306 class codes and definitions. Descriptions of the 21 NLCD 92 classifications are from the USGS Land Cover Institute (LCI) (http://landcover.usgs.gov/classes.php). Descriptions of the NLCDe 92 classifications are from Nakagaki and others (2007). 11. Open Water - areas of open water, generally with less than 25 percent cover of vegetation/land cover. 12. Perennial Ice/Snow - areas characterized by year-long surface cover of ice and/or snow. 21. Low Intensity Residential - areas with a mixture of constructed materials and vegetation. Constructed materials account for 30-80 percent of the cover. Vegetation may account for 20-70 percent of the cover. These areas most commonly include single-family housing units. Population densities will be lower than in high intensity residential areas. 22. High Intensity Residential - highly developed areas where people reside in high numbers. Examples include apartment complexes and row houses. Vegetation accounts for less than 20 percent of the cover. Constructed materials account for 80-100 percent of the cover. 23. Commercial/Industrial/Transportation - areas consisting of infrastructure (e.g. roads, railroads, etc.) and all highly developed areas not classified as "High Intensity Residential." 25. LULC Residential - areas that were not classified in the NLCD 92 as forest ("Deciduous Forest," "Evergreen Forest," or "Mixed Forest"), water ("Open Water," "Woody Wetlands," or "Emergent Herbaceous Wetlands") or urban ("Low Intensity Residential," "High Intensity Residential," "Commercial/Industrial/Transportation," "Urban/Recreational Grasses"), and were classified as "Residential" in the LULC data set. 26. NLCD/LULC Forested Residential - areas that were classified in the NLCD 92 as "Deciduous Forest," "Evergreen Forest," or "Mixed Forest" and as "Residential" in the LULC data set. 27. Newly Urbanized Without Trees - areas that were NOT classified in the NLCDe 92 as water ("Open Water"), developed ("Low Intensity Residential," "High Intensity Residential," "Commercial/Industrial/Transportation," "LULC Residential," "NLCD/LULC Forested Residential," "Urban/Recreational Grasses"), wetlands ("Woody Wetlands," "Emergent Herbaceous Wetlands"), or forest ("Deciduous Forest," "Evergreen Forest," or "Mixed Forest") and have 2000 population density of at least 1,000 people per square mile and 1990 population density of less than 1,000 people per square mile. 28. Newly Urbanized With Trees - areas that were classified in the NLCDe 92 as forest ("Deciduous Forest," "Evergreen Forest," or "Mixed Forest") and have 2000 population density of at least 1,000 people per square mile and 1990 population density of less than 1,000 people per square mile. 31. Bare Rock/Sand/Clay - perennially barren areas of bedrock, desert pavement, scarps, talus, slides, volcanic material, glacial debris, beaches, and other accumulations of earthen material. 32. Quarries/Strip Mines/Gravel Pits - areas of extractive mining activities with significant surface expression. 33. Transitional - areas of sparse vegetative cover (less than 25 percent of cover) that are dynamically changing from one land cover to another, often because of land use activities. Examples include forest clearcuts, a transition phase between forest and agricultural land, the temporary clearing of vegetation, and changes due to natural causes (e.g. fire, flood, etc.). 41. Deciduous Forest - areas dominated by trees where 75 percent or more of the tree species shed foliage simultaneously in response to seasonal change. 42. Evergreen Forest - areas dominated by trees where 75 percent or more of the tree species maintain their leaves all year. Canopy is never without green foliage. 43. Mixed Forest - areas dominated by trees where neither deciduous nor evergreen species represent more than 75 percent of the cover present. 51. Shrubland - areas characterized by shrubs; shrub canopy accounts for 25-100 percent of the cover. Shrub cover is generally greater than 25 percent when tree cover is less than 25 percent. Shrub cover may be less than 25 percent in cases when the cover of other life forms (e.g. herbaceous or tree) is less than 25 percent and shrubs cover exceeds the cover of the other life forms. 61. Orchards/Vineyards/Other - orchards, vineyards, and other areas planted or maintained for the production of fruits, nuts, berries, or ornamentals. 62. LULC Orchards/Vineyards/Other - areas that were not already classified as "Orchards/Vineyards/Other," nor any of the water or urban classifications in the NLCD 92 and as "Orchards, Groves, Vineyards, Nurseries, and Ornamental Horticultural Areas" in the LULC data set. (California, Oregon, Washington, and Florida areas were excluded from reclassification to "LULC Orchards/Vineyards/Other"). 71. Grasslands/Herbaceous - areas dominated by upland grasses and forbs. In rare cases, herbaceous cover is less than 25 percent, but exceeds the combined cover of the woody species present. These areas are not subject to intensive management, but they are often utilized for grazing. 72. LULC Tundra - areas that were classified in the NLCD 92 as either "Shrubland" or "Grasslands/Herbaceous" and as "Shrub and Brush Tundra," "Herbaceous Tundra," "Bare Ground Tundra," "Wet Tundra," or "Mixed Tundra" in the LULC data set. 81. Pasture/Hay - areas of grasses, legumes, or grass-legume mixtures planted for livestock grazing or the production of seed or hay crops. 82. Row Crops - areas used for the production of crops, such as corn, soybeans, vegetables, tobacco, and cotton. 83. Small Grains - areas used for the production of graminoid crops such as wheat, barley, oats, and rice. 84. Fallow - areas used for the production of crops that do not exhibit visible vegetation as a result of being tilled in a management practice that incorporates prescribed alternation between cropping and tillage. 85. Urban/Recreational Grasses - (areas of) vegetation (primarily grasses) planted in developed settings for recreation, erosion control, or aesthetic purposes. Examples include parks, lawns, golf courses, airport grasses, and industrial site grasses. 91. Woody Wetlands - areas where forest or shrubland vegetation accounts for 25-100 percent of the cover and the soil or substrate is periodically saturated with or covered with water. 92. Emergent Herbaceous Wetlands - areas where perennial herbaceous vegetation accounts for 75-100 percent of the cover and the soil or substrate is periodically saturated with or covered with water. 99. Missing Data - areas within the county boundaries of the conterminous United States that fell beyond the map extent of the NLCD 92 and thus do not have land-cover codes. These areas are generally along the U.S. borders and coastlines. BACKGROUND REFERENCES: Geolytics, Inc., 2001, CensusCD 2000 short form blocks: East Brunswick, N.J., digital data on CDROM. Hamilton, P.A., Miller, T.L., and Myers, D.N., 2004, Water quality in the Nation's streams and aquifers--Overview of selected findings, 1991-2001: U.S. Geological Survey Circular 1265, 20 p. Hitt, K.J., 1994, Refining 1970's land-use data with 1990 population data to indicate new residential development: U.S. Geological Survey Water-Resources Investigations Report 94-4250, 15 p. Homer, C., Huang, C., Yang, L., Wylie, B., and Coan, M., 2004, Development of a 2001 national land cover database for the United States: Photogrammetric Engineering and Remote Sensing, vol. 70, no. 7, p. 829-840. Nakagaki, N., Price, C.V., Falcone, J.A., Hitt, K.J., Ruddy, B.C., 2007, Enhanced national land cover data 1992 (NLCDe 92), digital data, accessed September 2005, at http://water.usgs.gov/lookup/getspatial?nlcde92. National Oceanic and Atmospheric Administration, National Ocean Service, 1994, NOS80K/ALLUS80K medium-resolution digital vector U.S. shoreline shapefile, accessed August 2005, at http://coastalmap.marine.usgs.gov/GISdata/basemaps/coastlines/nos80k/allus80k.htm. [ Currently (2008) available at http://woodshole.er.usgs.gov/pubs/of2005-1048/data/basemaps/usa/nos80k/nos80k.htm ] Price, C.V., Nakagaki, N., Hitt, K.J., Clawges, R.M., 2007, Enhanced historical land-use and land-cover data sets of the U.S. Geological Survey: U.S. Geological Survey Data Series 240, accessed August 2007, at http://pubs.usgs.gov/ds/2006/240/. U.S. Bureau of the Census, 1991, Census of population and housing, 1990: Public Law 94-171 data (United States), [machine readable data files]: Washington, DC, The Bureau [producer and distributor]. U.S. Bureau of the Census, Geography Division, 1990, Cartographic boundary files--Census 1990 block group, digital data, accessed February 2003, at http://www.census.gov/geo/www/cob/bg1990.html. U.S. Bureau of the Census, Geography Division, 2001a, Cartographic boundary files--Census 2000 block group, digital data, accessed August 2002, at http://www.census.gov/geo/www/cob/bg2000.html. U.S. Bureau of the Census, Geography Division, 2001b, 2000 TIGER/Line files for Denver, CO (08031), Jefferson, CO (08059), Adams, CO (08001), Arapahoe, CO (08005), Montgomery, MD (24031), Gallatin, MT (30031), Bedford City, VA (51515), Covington, VA (51580), Fairfax City, VA (51600), Franklin City, VA (51620), Manassas Park City, VA (51685), and Waynesboro City, VA (51820), digital files, accessed August 2005, at http://www.census.gov/geo/www/tiger/index.html. U.S. Bureau of the Census, Geography Division, 2005, 2004 TIGER/Line files for Broomfield, CO (08014), digital files, accessed August 2005, at http://www.census.gov/geo/www/tiger/index.html. U.S. Department of Agriculture, 2004, 2002 Census of Agriculture, Geographic area series, 1A and 1B, Washington, DC, U.S. summary and county level data file: U.S. Department of Agriculture, National Agricultural Statistics Service (NASS) [producer and distributor]. [CD-ROM]. U.S. Department of Commerce, Bureau of the Census, 1993, 1:100,000-scale counties of the United States, digital map, accessed September 2005, at http://water.usgs.gov/lookup/getspatial?county100. U.S. Department of Commerce, Bureau of the Census, 1996, TIGER/Line Files, 1995 Technical Documentation: Bureau of the Census, Washington, DC. U.S. Geological Survey, 1999, National land cover data 1992, digital files, accessed August 2005, at http://landcover.usgs.gov/natllandcover.php. APPLICATIONS The NAWQA Program has used NLCDep0306 to summarize 2000 land use percentages in watersheds. In addition, NLCDep0306 was combined with county boundaries and other ancillary data to improve the spatial distribution of chemicals (nutrients and pesticides) and agricultural practices applied to the land surface during the timeframe of approximately 2000-2004. LIMITATIONS Newly urbanized areas indicated by NLCDep0905 and NLCDep0306 were spot checked with urbanized areas depicted by NLCDe 92 and NLCD 2001 for several locations around the country (Thomas Trombley, USGS, written commun., 2008). The locations were 1. Shrewsbury, Westborough, and Marlborough, MA; 2. Homewood, AL; 3. Lawrence, KS; 4. Las Vegas, NV; and 5. Rapid City, SD. Although the various national land cover data sets are not directly comparable because of different methodolgies, they still can be used qualitatively for visual inspection and overall impression. The visual comparisons showed that urban development depicted in NLCD 2001 tends to be a proportional expansion around previously urbanized areas. On the other hand, newly urbanized areas shown in NLCDep0905 and NLCDep0306 often fill entire block groups. Although NLCDep0306 is less extreme than NLCDep0905, both data sets overestimate newly urbanized areas. Areas indicated as forested in NLCDe 92 tend to be forested in NLCD 2001 as well. In contrast, the newly urbanized lands shown in NLCDep0905 and NLCDep0306 include extensive areas that were classified as forested in the NLCDe 92. However, to counteract this limitation, users can distinguish the newly urbanized areas previously classified as forested because these areas are coded separately as "Newly Urbanized With Trees." Areas that were not previously classified as forested are coded as "Newly Urbanized Without Trees." Newly urbanized areas in NLCDep0905 and NLCDep0306 were based on population data only, and population data alone do not adequately address other types of urban development such as commercial, industrial, and transportation. 2000 The data set is intended to represent conditions in the early 2000s. However, the source data set NLCDe 92 was developed from NLCD 1992, which was based on satellite imagery collected during 1986-1995, and from land use/land-cover data (LULC), which was based on aerial photographs taken during the 1970s-1980s. Complete None planned -128.307900 -65.143599 51.857938 22.736542 None National Water Quality Assessment NAWQA land use land cover National Land Cover Data Set NLCD 1992 NLCDe 92 NLCDep GIRAS Geographic Information Retrieval and Analysis System Land use and Land Cover 2000 Census of population 1990 Census of population inlandWaters None Conterminous United States none Users should consider the methodology used in compiling this data set, which involved combining input data from several disparate sources, scales, and timeframes. As described in the Currentness_Reference, this data set was derived from data layers dating as far back as the 1970s. Population data can only approximate urban land cover. No ground verification was conducted to determine the accuracy of the recently urbanized land classification that was based on population density. The resolution of the data set is appropriate for regional and national analyses. http://water.usgs.gov/GIS/browse/nlcdep0306.jpg This is an image showing a national map of the 4 quadrants of NLCDep0306 and the land-cover classes. JPEG U.S. Geological Survey scientists David K. Mueller, Naomi Nakagaki, Barbara Ruddy, Jo Ann Gronberg, James Falcone, Gail Thelin, and Curtis Price were instrumental in developing the assumptions used to prepare this data set. The author acknowledges and thanks Terri L. Arnold and Thomas J. Trombley for their reviews of this data set and metadata. Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.1.1332 Kerie J. Hitt 2008 Version 2, September 2005 30-meter raster digital data Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?nlcdep0905 J.E. Vogelmann S.M. Howard L. Yang C.R. Larson B.K. Wylie N. Van Driel 2001 30-meter raster digital data Photogrammetric Engineering and Remote Sensing Journal of the American Society for Photogrammetry and Remote Sensing v. 67, no. 6, p. 650-662 http://landcover.usgs.gov/natllandcover.php http://www.asprs.org/publications/pers/2001journal/june/highlight.html Not applicable to raster data. Complete for conterminous United States. Naomi Nakagaki Curtis V. Price James A. Falcone Kerie J. Hitt Barbara C. Ruddy 200711 1.0, 2005 raster digital data Sacramento, CA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?nlcde92 digital files 1986 1995 Publication date NLCDe 92 This source provided land cover representative of the 1990s. NLCDe 92 is the nationally-consistent source of mapped land cover used by the USGS National Water-Quality Assessment Program to analyze data collected during the first decade of sampling from 1991-2001. NLCDe 92 has a 25-category land-cover classification scheme and is available as 30-meter resolution raster data. The NLCDe 92 was clipped to the U.S. boundary and shoreline. NLCDe 92 was reclassified according to a set of decision rules using 2000 population density to indicate land that changed to urban between 1992 and 2000. The derivative land-cover data set (NLCDep0306) has two additional land-cover classifications for newly urbanized land. GeoLytics, Inc. 2001 1.0 proprietary digital data CensusCD 2000 Short Form Blocks E. Brunswick, NJ GeoLytics, Inc. http://www.geolytics.com/census2000.htm digital files on CDROM 2000 2000 Census of Population and Housing USPOP00 This source provided the tabular population and land area data used in calculating 2000 population density for each block group. Population density in people per square kilometer was calculated from the tabular input data as pop2000 / (arealand / 1000000), where arealand is expressed in square meters. The population data are keyed to the 2000 block group boundaries using a block group identifier code. The 2000 population density values were used with 1990 population density to reclassify certain land-cover categories as newly urbanized land. The GeoLytics product contains all Census Short Form demographic data for over 8 million blocks from the 2000 U.S. Census of Population and Housing Summary File 1 (SF 1). Summary File 1 (SF 1) contains the 100-percent data, which is the information compiled from the questions asked of all people and about every housing unit. The GeoLytics product provided software to extract the population and housing unit data of interest in a format that could be imported into an automated geographic information system at the desired tabulation level. U.S. Bureau of the Census, Geography Division 200101 1.0 digital data Cartographic boundary Files Block groups http://www.census.gov/geo/www/cob/bg2000.html digital files retrieved 8/20/2002 2000 2000 USBG00 This source provided the generalized 2000 Census block group boundaries in vector format. The block group geographic boundaries are keyed to 2000 population density data by a block group identifier code. For processing NLCDep0306, each block group has an associated value of 2000 population density (people per square kilometer), which was obtained from Geolytics, Inc. (2001). The block group boundaries were converted from vector (polygon) format to grid format at a 30-meter resolution. The cartographic boundary files are a generalized extract from the U.S. Census Bureau's TIGER database. Line simplification/smoothing was performed with a tolerance of 0.005 decimal degrees and a coordinate reduction using the Douglas-Peucker method (1973) with a tolerance of 0.0003 decimal degrees. Very small polygons were eliminated when the combination of geographic codes existed elsewhere. The geography was clipped back to the shoreline of the United States, in contrast to TIGER/Line which shows the full extent of geography out to the 3-mile limit. Users of demographic data would need these boundaries or another set of block group boundaries such as the TIGER files to spatially represent demographic data. The population data is referenced to the block group boundary by the block group identifier. The generalized files have a much smaller file size than the original file extraction from the Census Bureau's TIGER data base, resulting in faster download and processing times. The cartographic boundary files are primarily designed for small scale, thematic mapping applications at a target scale range of 1:500,000 to 1:5,000,000. Because of coordinate thinning: 1. Cartographic boundary files should not be used for geocoding; 2. Some offshore, redundant, zero population and housing land areas may be absent from the cartographic boundary files; 3. Cartographic boundary files are not necessarily vertically integrated with previous boundary file sets. Reference cited Douglas, D.H., and Peucker, T.K., 1973, Algorithms for the reduction of the number of points required to represent a digitized line or its caricature: The Canadian Cartographer vol. 10, no. 2, pages 112-122. U.S. Department of Commerce, U.S. Bureau of the Census 1993 vector digital data http://water.usgs.gov/lookup/getspatial?county100 online 1990 1990 county100 This data set furnished 1990 county boundaries and county codes that were used to develop the 30-meter resolution grid of 2000 county boundaries. The 1990 county boundaries were used as a starting point for consistency with the county grid used to process data for NLCDe 92. County changes that had occurred from 1990 to 2001 were obtained from 2000 TIGER/Line (U.S. Bureau of the Census, Geography Division, 2001b) and 2004 TIGER/Line (U.S. Bureau of the Census, Geography Division, 2005) files. The new linework and codes were incorporated into the 1990 county boundaries to update the data to 2000. The original county boundaries had no shorelines. The boundaries of coastal counties extended into the ocean. The county boundaries were combined with a medium resolution shoreline (National Oceanic and Atmospheric Administration, 1994). The combined county/shoreline grid (CO2001G) was used to clip the NLCDep0306 land-cover grids. National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Office of Coast Survey, and the Strategic Environmental Assessments (SEA) Division of the Office of Ocean Resources Conservation and Assessment (ORCA) 1994 vector digital data http://woodshole.er.usgs.gov/pubs/of2005-1048/data/basemaps/usa/nos80k/nos80k.htm online 1988 1992 1994 ALLUS80K This is a 1:70,000-scale vector data set of the coastline of the contiguous United States that was compiled from NOAA coast charts. The original county boundaries had no shorelines (U.S. Department of Commerce, U.S. Bureau of the Census, 1993). The boundaries of coastal counties extended into the ocean. The county boundaries were combined with the medium resolution shoreline. The combined county/shoreline grid (CO2001G) was used to clip the NLCDep0306 land-cover grids. U.S. Bureau of the Census 1991 tabular digital data Washington, DC U.S. Bureau of the Census digital files on CDROM 1991 1990 Census of Population and Housing USPOP90 This source provided the tabular population and land area data used in calculating 1990 population density for each block group. Population density in people per square kilometer was calculated from the tabular input data as pop1990 / (arealand / 1000000), where arealand is square meters. The population data are keyed to the 1990 block group boundaries using a block group identifier code. The 1990 population density values were used with 2000 population density to reclassify certain land-cover categories as newly urbanized land. U.S. Bureau of the Census, Geography Division 199001 1.0 digital data Cartographic Boundary Files Block groups http://www.census.gov/geo/www/cob/bg1990.html digital files retrieved 2/14/2003 1990 1990 USBG90 This source provided the generalized 1990 Census block group boundaries in vector format. The block group geographic boundaries are keyed to 1990 population density data by a block group identifier code. For processing NLCDep0306, each block group has an associated value of 1990 population density (people per square kilometer), which was obtained from the 1990 Census of Population and Housing (U.S. Bureau of the Census, 1991). The block group boundaries were converted from vector (polygon) format to grid format at 30-meter resolution. The cartographic boundary files are a generalized extract from the U.S. Census Bureau's TIGER database. Line simplification/smoothing was performed with a tolerance of 0.005 decimal degrees and a coordinate reduction using the Douglas-Peucker method (1973) with a tolerance of 0.0003 decimal degrees. Very small polygons were eliminated when the combination of geographic codes existed elsewhere. The geography was clipped back to the shoreline of the United States, in contrast to TIGER/Line which shows the full extent of geography out to the 3-mile limit. Users of demographic data would need these boundaries or another set of block group boundaries such as the TIGER files to spatially represent demographic data. The population data is referenced to the block group boundary by the block group identifier. The generalized files have a much smaller file size than the original file extraction from the Census Bureau's TIGER data base, resulting in faster download and processing times. The cartographic boundary files are primarily designed for small scale, thematic mapping applications at a target scale range of 1:500,000 to 1:5,000,000. Because of coordinate thinning: 1. Cartographic boundary files should not be used for geocoding; 2. Some offshore, redundant, zero population and housing land areas may be absent from the cartographic boundary files; 3. Cartographic boundary files are not necessarily vertically integrated with previous boundary file sets. Reference cited Douglas, D.H., and Peucker, T.K., 1973, Algorithms for the reduction of the number of points required to represent a digitized line or its caricature: The Canadian Cartographer vol. 10, no. 2, pages 112-122. The input data sets consist of 30-meter resolution ESRI ArcInfo Workstation GRIDS of NLCDe 92 (1990 land cover), 1990 population density, and 2000 population density. The NLCDe 92 is organized in 4 tiles, one for each quadrant of the conterminous United States. Each tile was overlaid with the population density grids and four updated tiles of NLCDep0306 were produced. The general procedure was to change the land-cover classification of any area in the NLCDe 92 having 2000 population density equal to or greater than 1,000 people per square mile (386 people per square kilometer) and 1990 population density less than 1,000 people per square mile to "newly urbanized land" if the NLCDe 92 category is not water (code 11), developed (codes 21, 22, 23, 25, 26, 85), or wetlands (codes 91, 92). If 2000 population density is equal to or greater than 1,000 people per square mile and 1990 population density is less than 1,000 people per square mile and NLCDe 92 is forested (codes 41, 42, 43), then the classification of the area was changed to "Newly Urbanized With Trees" (code 28). If the 1990 and 2000 urban population cutoffs are met, but NLCDe 92 is not forested, then the classification was changed to "newly urbanized without trees" (code 27). If the 2000 population density is less than 1,000 people per square mile or the 1990 population density is at least 1,000 people per square mile, the original NLCDe 92 classification was preserved regardless of the original classification. The ArcInfo Workstation Grid commands that were used to modify the NLCDe 92 land-cover classification codes to produce NLCDep0306 are shown below. The commands were run for each of the 4 tiles of NLCDe 92. First a grid of the "urban change" areas that meet the population criteria is prepared for each tile. >/*Get areas that were NOT considered "urban" in 1990 but ARE considered "urban" in 2000 >/*according to population density cut off of 386 people/km2 (1000 people/mi2) >/*usbg90g = 30-m resolution 1990 block group grid >/*usbg00g = 30-m resolution 2000 block group grid >/*uspop90.freq = table of 1990 population density by block group >/*uspop00.dat = table of 2000 population density by block group >/*turbcg = temporary urban change grid >/*nlcdeg = 30-meter resolution NLCDe 92 quadrant grid (1-4) >/*nlcdepg = 30-meter resolution NLCDep0306 quadrant grid (output > product) >/ >&args tile /*tile 1-4 >&set popdir d:/ancill/pop >setwindow c:/data/nlcde30m/nlcde4 %popdir%/usbg90g >setcell 30 >/*Relate to tabular population density data to use the 30-m block group grids >/*instead of the 100-m population density grids >relate add >p1 >d:/ancill/pop/uspop90.freq >info >bgi >bgi >ordered >rw >p2 >d:/ancill/pop/uspop00.dat >info >bgi >bgi >ordered >rw >~ >/*Get areas that were not "urban" in 1990 and are "urban" in 2000 >/*Using 30-m block group grids with related tabular population density data >turbcg%tile% = con (%popdir%/usbg90g.p1//pdens lt 386 & %popdir%/usbg00g.p2//pperkm2 ge 386,1,0) Next the urban change grid is overlaid with the land cover grid, and the land cover is reclassified in areas where the urban change grid is coded recent urban. >%nlcdepg% = con(isnull(%turbcg%),%nlcdeg%,~ con(%turbcg% eq 1 > and isnull(%nlcdeg% in {11,21,22,23,25,26,85,91,92}), con > (isnull(%nlcdeg% in {41,42,43}),27,28),%nlcdeg%)) 20060306 To line up the land-cover data with the 30-meter 2001 county/shoreline grid (CO2001G), we clipped each NLCDep0306 land-cover tile to the county/shoreline and filled in areas of NLCDep0306 without land-cover codes as missing data (code 99). Missing data in the original NLCD 92 occurs in a northern section of Cook county, MN (land) and in 10 other counties along the shoreline (water). These were recoded as 99. >FIPS NUMBER OF STATE COUNTY NAME > CELLS >06025 1 CA IMPERIAL >12087 454 FL MONROE >26033 1 MI CHIPPEWA >27031 20,342 MN COOK >27071 50 MN KOOCHICHING >27077 7 MN LAKE OF THE WOODS >27137 400 MN ST LOUIS >36019 1,782 NY CLINTON >36033 2,285 NY FRANKLIN >36045 37 NY JEFFERSON >36089 2,341 NY ST LAWRENCE Clipping to the county/shoreline removed the band of NLCDep0306 water cells that extended beyond the shoreline of the county grid and some other NLCDep0306 land-cover categories that extended beyond the county lines into Canada or Mexico on land. We did not remove NLCDep0306 cells that fell within the county grid, but we recoded areas missing from NLCDep0306 as missing data where the land-cover grid did not extend out to the boundary cells of the county grid. Cells were coded as missing data mostly along the shoreline and along the international border. The ArcInfo Workstation Grid commands for clipping the land cover to the 2001 county/shoreline grid and coding areas of missing land-cover data as 99 are: >/*county_grid is the 30-meter resolution county/shoreline grid >/*nlcdep_orig is the 30-meter resolution unclipped NLCDep0306 > quadrant grid >/*nlcdep_with99 is the 30-meter clipped NLCDep0306 quadrant >grid >/* >setmask county_grid >nlcdep_with99 = con(isnull(nlcdep_orig),99,nlcdep_orig) As a check, the cell counts for the final NLCDe 92 grids were compared to the cell counts for the final NLCDep0306 grids to verify that water, urban, and wetlands counts are the same. > Input Output Changes between > NLCDe92_1.vat NLCDep0306_1.vat input and output > VALUE COUNT VALUE COUNT COUNT PERCENT > CHANGE CHANGE > 11 34562023 11 34562023 0 0.00 > 12 1522059 12 1522046 -13 0.00 > 21 10885977 21 10885977 0 0.00 > 22 394874 22 394874 0 0.00 > 23 6937250 23 6937250 0 0.00 > 25 3270047 25 3270047 0 0.00 > 26 2462687 26 2462687 0 0.00 > -- 27 1526131 1526131 na > -- 28 392540 392540 na > 31 54768610 31 54748842 -19768 -0.04 > 32 1012929 32 1005239 -7690 -0.76 > 33 16999910 33 16992701 -7209 -0.04 > 41 48638505 41 48535087 -103418 -0.21 > 42 534717319 42 534536958 -180361 -0.03 > 43 33122317 43 33013556 -108761 -0.33 > 51 683048136 51 682821990 -226146 -0.03 > 61 6499183 61 6409679 -89504 -1.38 > 62 118726 62 116262 -2464 -2.08 > 71 694633081 71 694154442 -478639 -0.07 > 72 10121565 72 10121565 0 0.00 > 81 95027214 81 94567710 -459504 -0.48 > 82 97612033 82 97515917 -96116 -0.10 > 83 147567073 83 147456218 -110855 -0.08 > 84 76364429 84 76336206 -28223 -0.04 > 85 1176224 85 1176224 0 0.00 > 91 5148172 91 5148172 0 0.00 > 92 19160876 92 19160876 0 0.00 > > Input Output Changes between > NLCDe92_2.vat NLCDep0306_2.vat input and output > VALUE COUNT VALUE COUNT COUNT PERCENT > CHANGE CHANGE > 11 44938928 11 44938928 0 0.00 > 21 34396093 21 34396093 0 0.00 > 22 9657233 22 9657233 0 0.00 > 23 18037821 23 18037821 0 0.00 > 25 4661354 25 4661354 0 0.00 > 26 9272478 26 9272478 0 0.00 > -- 27 3266616 3266616 na > -- 28 2197386 2197386 na > 31 703105 31 695006 -8099 -1.15 > 32 2728102 32 2680450 -47652 -1.75 > 33 5363057 33 5323744 -39313 -0.73 > 41 403925959 41 402327422 -1598537 -0.40 > 42 80534812 42 80368942 -165870 -0.21 > 43 120896603 43 120463624 -432979 -0.36 > 51 1842196 51 1841295 -901 -0.05 > 61 53459 61 53043 -416 -0.78 > 62 2044587 62 2025707 -18880 -0.92 > 71 26457203 71 26396079 -61124 -0.23 > 81 264694569 81 263381634 -1312935 -0.50 > 82 567086957 82 565318879 -1768078 -0.31 > 83 12737564 83 12728346 -9218 -0.07 > 84 10749 84 10749 0 0.00 > 85 8801165 85 8801165 0 0.00 > 91 90147764 91 90147764 0 0.00 > 92 33047052 92 33047052 0 0.00 > 99 27245 99 27245 0 0.00 > > Input Output Changes between > NLCDe92_3.vat NLCDep0306_3.vat input and output > VALUE COUNT VALUE COUNT COUNT PERCENT > CHANGE CHANGE > 11 9212044 11 9212044 0 0.00 > 12 166540 12 166513 -27 -0.02 > 21 9738777 21 9738777 0 0.00 > 22 2157643 22 2157643 0 0.00 > 23 6959871 23 6959871 0 0.00 > 25 3414225 25 3414225 0 0.00 > 26 761633 26 761633 0 0.00 > -- 27 2531267 2531267 na > -- 28 171294 171294 na > 31 64489598 31 64298310 -191288 -0.30 > 32 953433 32 948540 -4893 -0.51 > 33 231606 33 221580 -10026 -4.33 > 41 26468976 41 26423042 -45934 -0.17 > 42 221886647 42 221785559 -101088 -0.05 > 43 8519702 43 8495430 -24272 -0.28 > 51 860620187 51 859531397 -1088790 -0.13 > 61 7351712 61 7279968 -71744 -0.98 > 62 913194 62 859310 -53884 -5.90 > 71 535229626 71 534740470 -489156 -0.09 > 72 4520206 72 4520206 0 0.00 > 81 50482686 81 50215969 -266717 -0.53 > 82 110311711 82 110038980 -272731 -0.25 > 83 91032136 83 90954003 -78133 -0.09 > 84 3207950 84 3204072 -3878 -0.12 > 85 1301625 85 1301625 0 0.00 > 91 585785 91 585785 0 0.00 > 92 1781561 92 1781561 0 0.00 > 99 1 99 1 0 0.00 > > Input Output Changes between > NLCDe92_4.vat NLCDep0306_4.vat input and output > VALUE COUNT VALUE COUNT COUNT PERCENT > CHANGE CHANGE > 11 54483791 11 54483791 0 0.00 > 21 36185928 21 36185928 0 0.00 > 22 11176863 22 11176863 0 0.00 > 23 18572480 23 18572480 0 0.00 > 25 7724835 25 7724835 0 0.00 > 26 12907261 26 12907261 0 0.00 > -- 27 3127290 3127290 na > -- 28 3151285 3151285 na > 31 2373207 31 2334624 -38583 -1.63 > 32 2673363 32 2650446 -22917 -0.86 > 33 32200587 33 32098570 -102017 -0.32 > 41 544016777 41 542672224 -1344553 -0.25 > 42 273043885 42 271984660 -1059225 -0.39 > 43 209863174 43 209115667 -747507 -0.36 > 51 18724862 51 18623936 -100926 -0.54 > 61 4626640 61 4519926 -106714 -2.31 > 62 1670386 62 1661604 -8782 -0.53 > 71 111337767 71 110956930 -380837 -0.34 > 81 383239657 81 381797765 -1441892 -0.38 > 82 313320000 82 31247446 -845532 -0.27 > 83 44634786 83 44555696 -79090 -0.18 > 84 8426 84 8426 0 0.00 > 85 8769904 85 8769904 0 0.00 > 91 149855203 91 149855203 0 0.00 > 92 55300522 92 55300522 0 0.00 > 99 454 99 454 0 0.00 The method used to produce the NLCDep0905 data set considered any area having 2000 population density of at least 1,000 people per square mile as being recently urbanized. The NLCDep0905 approach was determined to have misclassified lands that already were urban in 1990 as newly urbanized. The method used to produce NLCDep0306 was corrected for this and resulted in a smaller area called newly urbanized than in NLCDep0905, as shown by the cell counts below. >NLCDep0905_1.vat NLCDep0306_1.vat Changes >VALUE COUNT VALUE COUNT COUNT PERCENT > CHANGE CHANGE >27 3418947 27 1526131 -1892816 -155.4 >28 1107761 28 392540 -715221 -164.6 > > >NLCDep0905_2.vat NLCDep0306_2.vat Changes >VALUE COUNT VALUE COUNT COUNT PERCENT > CHANGE CHANGE >27 7572697 27 3266616 -4306081 -156.9 >28 7698713 28 2197386 -5501327 -171.5 > > >NLCDep0905_3.vat NLCDep0306_3.vat Changes >VALUE COUNT VALUE COUNT COUNT PERCENT > CHANGE CHANGE >27 6033406 27 2531267 -3502139 -158.0 >28 541139 28 171294 -369845 -168.3 > > >NLCDep0905_4.vat NLCDep0306_4.vat Changes >VALUE COUNT VALUE COUNT COUNT PERCENT > CHANGE CHANGE >27 6837650 27 3127290 -3710360 -154.3 >28 7760650 28 3151285 -4609365 -159.4 20060307 The 4 tile grids were converted from ArcInfo Workstation GRIDs to GeoTIFF images for distribution. They were converted to images using the ArcInfo Workstation Grid command "gridimage" specifying colors using a color map file and compression using packbits. >GRIDIMAGE c:/data/nlcdep30m_v1/nlcdep1 nlcdep0306.clr nlcdep0306_1 TIF COMPRESSION The GeoTIFF image format allows red-green-blue (RGB) color values to be assigned to the index values and stores them in the TIFF image header. The index values correspond to the NLCDep0306 land-cover codes. The colors are used for displaying the values. Here is the GeoTIFF colormap: >Value Red Green Blue Land-Cover Classification >00 000 000 000 No Data (outside of conterminous U.S.) >11 000 182 235 Open Water >12 240 240 241 Perennial Ice/Snow >21 251 222 229 Low Intensity Residential >22 242 133 173 High Intensity Residential >23 214 000 121 Commercial/Industrial/Transportation >25 224 175 198 LULC Residential >26 199 110 151 NLCD/LULC Forested Residential >27 143 000 176 Newly Urbanized Without Trees >28 176 000 156 Newly Urbanized With Trees >31 174 085 071 Bare Rock/Sand/Clay >32 191 147 134 Quarries/Strip Mines/Gravel Pits >33 136 082 050 Transitional >41 154 210 173 Deciduous Forest >42 000 145 070 Evergreen Forest >43 139 197 062 Mixed Forest >51 198 151 058 Shrubland >61 198 159 201 Orchards/Vineyards/Other >62 143 062 151 LULC Orchards/Vineyards/Other >71 233 209 174 Grasslands/Herbaceous >72 208 210 211 LULC Tundra >81 251 240 208 Pasture/Hay >82 254 246 156 Row Crops >83 251 174 022 Small Grains >84 254 211 000 Fallow >85 229 239 202 Urban/Recreational Grasses >91 152 214 219 Woody Wetlands >92 050 149 173 Emergent Herbaceous Wetlands >99 099 099 099 Missing land-cover data 200805 Raster Grid Cell 44167 (NLCDep0306_1,NLCDep0306_2); 53833 (NLCDep0306_3,NLCDep0306_4) 73167 (NLCDep0306_1,NLCDep0306_3); 81666 (NLCDep0306_2,NLCDep0306_4) 1 Albers Conical Equal Area 29.5 45.5 -96.0 23.0 0.0 0.0 row and column 30.0 30.0 meters North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 GeoTIFF image pixel any of the data elements in the TIFF file USGS GeoTIFF image value index value and numeric code representing a land-cover classification USGS, National Land Cover Data Set 1992 0 No data Value assigned during processing of NLCDep0306 - Any area around the perimeter of the United States that falls outside the extent of the county/shoreline grid was classified as no data. 11 Open Water Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 12 Perennial Ice/Snow Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 21 Low Intensity Residential Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 22 High Intensity Residential Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 23 Commercial/Industrial/Transportation Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 25 LULC Residential Nakagaki, N., Price, C.V., Falcone, J.A., Hitt, K.J., Ruddy, B., 2007, Enhanced national land cover data 1992 (NLCDe 92), digital data, accessed September 2005, at http://water.usgs.gov/lookup/getspatial?nlcde92. 26 NLCD/LULC Forested Residential Nakagaki, N., Price, C.V., Falcone, J.A., Hitt, K.J., Ruddy, B., 2007, Enhanced national land cover data 1992 (NLCDe 92), digital data, accessed September 2005, at http://water.usgs.gov/lookup/getspatial?nlcde92. 27 Newly Urbanized Without Trees Value assigned during processing of NLCDep0306 - Any area (excluding water, developed land, wetlands or forest) with 2000 population density of at least 1,000 people per square mile and 1990 population density of less than 1,000 people per square mile was reclassified as "Newly Urbanized Without Trees" in the derivative product. 28 Newly Urbanized With Trees Value assigned during processing of NLCDep0306 - Any area (excluding water, developed land, or wetlands) that was forest in NLCDe 92 with 2000 population density of at least 1,000 people per square mile and 1990 population density of less than 1,000 people per square mile was reclassified as "Newly Urbanized With Trees" in the derivative product. 31 Bare Rock/Sand/Clay Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 32 Quarries/Strip Mines/Gravel Pits Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 33 Transitional Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 41 Deciduous Forest Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 42 Evergreen Forest Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 43 Mixed Forest Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 51 Shrubland Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 61 Orchards/Vineyards/Other Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 62 LULC Orchards/Vineyards/Other Nakagaki, N., Price, C.V., Falcone, J.A., Hitt, K.J., Ruddy, B., 2007, Enhanced national land cover data 1992 (NLCDe 92), digital data, accessed September 2005, at http://water.usgs.gov/lookup/getspatial?nlcde92. 71 Grasslands/Herbaceous Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 72 LULC Tundra Nakagaki, N., Price, C.V., Falcone, J.A., Hitt, K.J., Ruddy, B., 2007, Enhanced national land cover data 1992 (NLCDe 92), digital data, accessed September 2005, at http://water.usgs.gov/lookup/getspatial?nlcde92. 81 Pasture/Hay Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 82 Row Crops Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 83 Small Grains Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 84 Fallow Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 85 Urban/Recreational Grasses Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 91 Woody Wetlands Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 92 Emergent Herbaceous Wetlands Vogelmann, J.E., Howard, S.M., Yang, L., Larson, C.R., Wylie, B.K., and Van Driel, N., 2001, Completion of the 1990's National Land Cover Data Set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources: Photogrammetric Engineering and Remote Sensing, v. 67, p. 650-662. 99 Missing Data Value assigned during processing of NLCDep0306 - Any area around the perimeter of the United States within the extent of the county/shoreline grid without a valid land-cover code was classified as missing data. The value is the land-cover classification code. The explanations of the land-cover codes are shown in the table below. Full descriptions are in Supplemental_Information. >NLCDep0306 Land-Cover Classes (modified from NLCDe 92 classification) > > * indicates a new class created by overlaying NLCDe 92 and 1990/2000 population data. > > VALUE Land-Cover Classification >------- ------------------------------------------------------- > 0 No data (Outside conterminous United States) > 11 Open Water > 12 Perennial Ice/Snow > 21 Low Intensity Residential > 22 High Intensity Residential > 23 Commercial/Industrial/Transportation > 25 LULC Residential > 26 NLCE/LULC Residential > * 27 Newly Urbanized Without Trees > * 28 Newly Urbanized With Trees > 31 Bare Rock/Sand/Clay > 32 Quarries/Strip Mines/Gravel Pits > 33 Transitional > 41 Deciduous Forest > 42 Evergreen Forest > 43 Mixed Forest > 51 Shrubland > 61 Orchards/Vineyards/Other > 62 LULC Orchards/Vineyards > 71 Grasslands/Herbaceous > 72 LULC Tundra > 81 Pasture/Hay > 82 Row Crops > 83 Small Grains > 84 Fallow > 85 Urban/Recreational Grasses > 91 Woody Wetlands > 92 Emergent Herbaceous Wetlands > 99 Missing Data (but within county boundaries) Descriptions of the 21 NLCD 92 classifications are from USGS Land Cover Institute (LCI) (http://landcover.usgs.gov/classes.php). Descriptions of the NLCDe 92 classifications are from Nakagaki and others (2007). U.S. Geological Survey Ask USGS -- Water Webserver Team Mailing address

445 National Center

Reston VA 20192 USA 1-888-275-8747 (1-888-ASK-USGS) http://water.usgs.gov/user_feedback_form.html Although this data set has 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 and related materials. 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. 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, this metadata file may include some vendor-specific terminology. GeoTIFF Categorical raster data for northwest quadrant of the United States ZIP-format archive 365513 KB http://water.usgs.gov/GIS/dsdl/nlcdep0306_1.zip GeoTIFF Categorical raster data for northeast quadrant of the United States ZIP-format archive 345788 KB http://water.usgs.gov/GIS/dsdl/nlcdep0306_2.zip GeoTIFF Categorical raster data for southwest quadrant of the United States ZIP-format archive 283883 KB http://water.usgs.gov/GIS/dsdl/nlcdep0306_3.zip GeoTIFF Categorical raster data for southeast quadrant of the United States ZIP-format archive 537187 KB http://water.usgs.gov/GIS/dsdl/nlcdep0306_4.zip None. This data set is provided by USGS as a public service. 20080605 U.S. Geological Survey Ask USGS -- Water Webserver Team mailing address

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Reston VA 20192 USA 1-888-275-8747 (1-888-ASK-USGS) http://water.usgs.gov/user_feedback_form.html FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998