1970's Land use data refined with 1990 population data to indicate new residential development for the conterminous United States

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Frequently-anticipated questions:


What does this data set describe?

Title:
1970's Land use data refined with 1990 population data to indicate new residential development for the conterminous United States
Abstract:
This data set represents U.S. Geological Survey (USGS) historical Land Use and Land Cover (LULC) from the 1970's that has been refined with 1990 population density at the block group level to indicate new residential development representative of the 1990's. Any area having a population density of at least 1,000 people per square mile had been re-classified as "urban" land in this data set.
Supplemental_Information:
This data set was developed by the NAWQA program to fill a requirement for a nationally consistent land-use data base that would define where "urban" land existed during the 1990's and where urbanization had occurred from the 1970's to the 1990's.
The best available nationally consistent land-use data base available at the time (1992) was the LULC data that was developed by USGS under the Land Use Data Analysis (LUDA) program in the 1970's-1980's. LULC maps were delineated manually from aerial photography, and LULC codes were assigned using a hierarchical land use and land cover classification scheme described by Anderson and others (1976). The maps were published by quadrangles at scales of 1:250,000 and 1:100,000 (USGS, 1990). The native digital format of the USGS LULC data is Geographic Information Retrieval and Analysis System (GIRAS).
In 1992, a similar nationally consistent LULC data base for the 1990's did not exist. NAWQA's approach was to take the 1970's LULC data as a base and then enhance it with more current, more detailed ancillary information on population (Hitt, 1994).
NAWQA developed a classification scheme for defining "residential" land use based on population density. The classification scheme determined "residential" land as any area with population density of at least 1,000 people per square mile (386 people per square kilometer).
The procedure to refine the LULC data was to overlay the 1970's land use with 1990 population density by block group. Any area in the derivative product that met the following criteria was re-assigned a new land use code of "new residential:" (1) original LULC land use was not urban or built-up, (2) original LULC land use was not water, and (3) 1990 population density was at least 1,000 people per square mile.
The ArcInfo Workstation grid is stored in the newlu90g.tgz file (gzipped tar file). The uncompressed file size of newlu90g.tar is about 109 MB. Ways to extract the grid from the .tgz archive file include TARARC, Winzip, UnStuffIt, or the following GNU utilities for WIN32:
gunzip newlu90g.tgz tar xvof newlu90g.tar
The grid "newlu90g" will be in a subdirectory called arctar00000.
arctar00000/ arctar00000/info/ arctar00000/info/arc.dir arctar00000/info/arc0000.dat arctar00000/info/arc0000.nit arctar00000/info/arc0001.dat arctar00000/info/arc0001.nit arctar00000/info/arc0002.dat arctar00000/info/arc0002.nit arctar00000/info/arc0002r.001 arctar00000/log arctar00000/newlu90g/ arctar00000/newlu90g/dblbnd.adf arctar00000/newlu90g/hdr.adf arctar00000/newlu90g/log arctar00000/newlu90g/prj.adf arctar00000/newlu90g/sta.adf arctar00000/newlu90g/vat.adf arctar00000/newlu90g/w001001.adf arctar00000/newlu90g/w001001x.adf arctar00000/newlu90g.aux
Related_Spatial_and_Tabular_Data_Sets:
The data set is provided as a GeoTIFF image (newlu90g.tif is contained in newlu90g.tar.gz) as well as native ArcInfo Workstation GRID format (newlu90g.tgz). The GeoTIFF file is provided as a nonproprietary format in case the user's software cannot access the data in ArcInfo Workstation GRID format. The uncompressed GeoTIFF file size is 1348131109 bytes.
The following table describes the index values stored in an embedded color map in the GeoTIFF image:
Index RGB Values Value R G B ----------------------------------------------------------------- 0 no data 10 255 20 147 11 255 0 255 12 255 0 0 13 208 32 144 14 255 105 180 15 255 192 203 16 238 130 238 17 255 228 225 21 255 215 0 22 255 255 0 23 255 140 0 24 238 221 130 31 255 250 205 32 244 164 96 33 218 165 32 41 152 251 152 42 0 255 0 43 124 252 0 51 135 206 250 52 0 191 255 53 0 255 255 54 175 238 238 61 127 255 212 62 72 209 204 71 233 150 122 72 184 134 11 73 210 180 140 74 165 42 42 75 188 143 143 76 139 69 19 77 143 188 143 81 218 112 214 82 123 104 238 83 138 43 226 84 0 0 205 85 160 32 240 91 211 211 211 92 105 105 105
The newlu90g.aux (auxiliary) file archived with the .tif file stores coordinate system information for the .tif file and is recognized by ArcGIS.
The newlu90g.clr (colormap) file specifies the colors to be used for displaying ArcInfo Workstation grid cell values. This is an ascii file containing the index numbers 0-255 followed by RGB values:
Index -- RGB Values --- Value red green blue (LULC code) ---------------------------- # value red green blue 0 30 30 30 1 30 30 30 2 30 30 30 3 30 30 30 4 30 30 30 5 30 30 30 6 30 30 30 7 30 30 30 8 30 30 30 9 30 30 30 10 255 20 147 11 255 0 255 12 255 0 0 13 208 32 144 14 255 105 180 15 255 192 203 16 238 130 238 17 255 228 225 18 30 30 30 19 30 30 30 20 30 30 30 21 255 215 0 22 255 255 0 23 255 140 0 24 238 221 130 25 30 30 30 26 30 30 30 27 30 30 30 28 30 30 30 29 30 30 30 30 30 30 30 31 255 250 205 32 244 164 96 33 218 165 32 34 30 30 30 35 30 30 30 36 30 30 30 37 30 30 30 38 30 30 30 39 30 30 30 40 30 30 30 41 152 251 152 42 0 255 0 43 124 252 0 44 30 30 30 45 30 30 30 46 30 30 30 47 30 30 30 48 30 30 30 49 30 30 30 50 30 30 30 51 135 206 250 52 0 191 255 53 0 255 255 54 175 238 238 55 30 30 30 56 30 30 30 57 30 30 30 58 30 30 30 59 30 30 30 60 30 30 30 61 127 255 212 62 72 209 204 63 30 30 30 64 30 30 30 65 30 30 30 66 30 30 30 67 30 30 30 68 30 30 30 69 30 30 30 70 30 30 30 71 233 150 122 72 184 134 11 73 210 180 140 74 165 42 42 75 188 143 143 76 139 69 19 77 143 188 143 78 30 30 30 79 30 30 30 80 30 30 30 81 218 112 214 82 123 104 238 83 138 43 226 84 0 0 205 85 160 32 240 86 30 30 30 87 30 30 30 88 30 30 30 89 30 30 30 90 30 30 30 91 211 211 211 92 105 105 105 93 30 30 30 94 30 30 30 95 30 30 30 96 30 30 30 97 30 30 30 98 30 30 30 99 30 30 30 100 30 30 30 101 30 30 30 102 30 30 30 103 30 30 30 104 30 30 30 105 30 30 30 106 30 30 30 107 30 30 30 108 30 30 30 109 30 30 30 110 30 30 30 111 30 30 30 112 30 30 30 113 30 30 30 114 30 30 30 115 30 30 30 116 30 30 30 117 30 30 30 118 30 30 30 119 30 30 30 120 30 30 30 121 30 30 30 122 30 30 30 123 30 30 30 124 30 30 30 125 30 30 30 126 30 30 30 127 30 30 30 128 30 30 30 129 30 30 30 130 30 30 30 131 30 30 30 132 30 30 30 133 30 30 30 134 30 30 30 135 30 30 30 136 30 30 30 137 30 30 30 138 30 30 30 139 30 30 30 140 30 30 30 141 30 30 30 142 30 30 30 143 30 30 30 144 30 30 30 145 30 30 30 146 30 30 30 147 30 30 30 148 30 30 30 149 30 30 30 150 30 30 30 151 30 30 30 152 30 30 30 153 30 30 30 154 30 30 30 155 30 30 30 156 30 30 30 157 30 30 30 158 30 30 30 159 30 30 30 160 30 30 30 161 30 30 30 162 30 30 30 163 30 30 30 164 30 30 30 165 30 30 30 166 30 30 30 167 30 30 30 168 30 30 30 169 30 30 30 170 30 30 30 171 30 30 30 172 30 30 30 173 30 30 30 174 30 30 30 175 30 30 30 176 30 30 30 177 30 30 30 178 30 30 30 179 30 30 30 180 30 30 30 181 30 30 30 182 30 30 30 183 30 30 30 184 30 30 30 185 30 30 30 186 30 30 30 187 30 30 30 188 30 30 30 189 30 30 30 190 30 30 30 191 30 30 30 192 30 30 30 193 30 30 30 194 30 30 30 195 30 30 30 196 30 30 30 197 30 30 30 198 30 30 30 199 30 30 30 200 30 30 30 201 30 30 30 202 30 30 30 203 30 30 30 204 30 30 30 205 30 30 30 206 30 30 30 207 30 30 30 208 30 30 30 209 30 30 30 210 30 30 30 211 30 30 30 212 30 30 30 213 30 30 30 214 30 30 30 215 30 30 30 216 30 30 30 217 30 30 30 218 30 30 30 219 30 30 30 220 30 30 30 221 30 30 30 222 30 30 30 223 30 30 30 224 30 30 30 225 30 30 30 226 30 30 30 227 30 30 30 228 30 30 30 229 30 30 30 230 30 30 30 231 30 30 30 232 30 30 30 233 30 30 30 234 30 30 30 235 30 30 30 236 30 30 30 237 30 30 30 238 30 30 30 239 30 30 30 240 30 30 30 241 30 30 30 242 30 30 30 243 30 30 30 244 30 30 30 245 30 30 30 246 30 30 30 247 30 30 30 248 30 30 30 249 30 30 30 250 30 30 30 251 30 30 30 252 30 30 30 253 30 30 30 254 30 30 30 255 30 30 30
-------------------------------------------------------------- Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
Use of trade names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.
  1. How should this data set be cited?

    Hitt, Kerie J., 20050315, 1970's Land use data refined with 1990 population data to indicate new residential development for the conterminous United States.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -128.002463
    East_Bounding_Coordinate: -65.258046
    North_Bounding_Coordinate: 51.691388
    South_Bounding_Coordinate: 22.838701

  3. What does it look like?

    <http://water.usgs.gov/GIS/browse/newlu90g.gif> (GIF)
    Map of 1970's land use refined with 1990 population data to indicate new residential development

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 1991
    Currentness_Reference:
    The data set is intended to represent conditions for the 1990's.

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: raster digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:

      • Dimensions 29150 x 46240 x 1, type Grid Cell

    2. What coordinate system is used to represent geographic features?

      The map projection used is Albers Conical Equal Area.

      Projection parameters:
      Standard_Parallel: 29.5
      Standard_Parallel: 45.5
      Longitude_of_Central_Meridian: -96
      Latitude_of_Projection_Origin: 23
      False_Easting: 0.00000
      False_Northing: 0.00000

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 100.0
      Ordinates (y-coordinates) are specified to the nearest 100.0
      Planar coordinates are specified in Meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378137.000.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    The value of each 100-m by 100-m grid cell is the level 2 land use and land cover classification code (Anderson and others, 1976) or a new level 2 code "10" (Hitt, 1994).
    The new code "10" indicates "new residential development," that is, areas having 1990 population density of at least 1,000 people per square mile (386 people per square kilometer) that were not urban or water in the source LULC data.
    The ArcInfo Workstation grid has a .VAT (value attribute table), with two fields, VALUE and COUNT.
    VALUE is the 2-digit LULC code (Anderson level 2) or new code "10."
    COUNT is the number of cells (assigned by ArcInfo) in each LULC class.
    The ArcInfo Workstation grid also has a .STA (statistics) file, with the items MIN, MAX, MEAN, and STDV.
    MIN is the minimum value in the grid (10).
    MAX is the maximum value in the grid (92).
    MEAN is the arithmetic mean of the values in the grid. (MEAN is meaningless for categorical LULC data.)
    STDV is the standard deviation of the values in the grid. (STDV is meaningless for categorical LULC data.)
    In the GeoTIFF image file, each index number corresponds to the 2-digit LULC code (Anderson level 2) or new code "10."
    Entity_and_Attribute_Detail_Citation:
    Land use and land cover classification codes and descriptions are provided in Anderson and others (1976). (See <http://landcover.usgs.gov/pdf/anderson.pdf>.)
    The Anderson classification system is:
    LEVEL 1 LEVEL 2 1 Urban or built-up land 11 Residential 12 Commercial and services 13 Industrial 14 Transportation, communication, and utilities 15 Industrial and commercial complexes 16 Mixed urban or built-up land 17 Other urban or built-up land
    2 Agricultural land 21 Cropland and pasture 22 Orchards, groves, vineyards, nurseries, and ornamental horticultural areas 23 Confined feeding operations 24 Other agricultural land
    3 Rangeland 31 Herbaceous rangeland 32 Shrub and brush rangeland 33 Mixed rangeland
    4 Forest land 41 Deciduous forest land 42 Evergreen forest land 43 Mixed forest land
    5 Water 51 Streams and canals 52 Lakes 53 Reservoirs 54 Bays and estuaries
    6 Wetland 61 Forested wetland 62 Nonforested wetland
    7 Barren land 71 Dry salt flats 72 Beaches 73 Sandy areas other than beaches 74 Bare exposed rock 75 Strip mines, quarries, and gravel pits 76 Transitional areas 77 Mixed barren land
    8 Tundra 81 Shrub and brush tundra 82 Herbaceous tundra 83 Bare ground tundra 84 Wet tundra 85 Mixed tundra
    9 Perennial snow or ice 91 Perennial snowfields 92 Glaciers


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?


Why was the data set created?

This is one of the ancillary GIS (geographic information system) data layers developed to characterize USGS National Water-Quality Assessment (NAWQA) sampling sites and study areas for national synthesis of water-quality data. For background on the design of the NAWQA program see Gilliom and others (1995).


How was the data set created?

  1. From what previous works were the data drawn?

    LULC (source 1 of 3)
    Fegeas, Robin G. , Claire, Robert W. , Guptill, Stephen C. , Anderson, K. Eric , and Hallam, Cheryl A. , 1983, Digital cartographic data standards: Land use and land cover digital data: USGS Circular 895-E, USGS, Reston, VA.

    Online Links:

    Type_of_Source_Media: digital
    Source_Scale_Denominator: 250000
    Source_Contribution:
    This data set provided land use and land cover representative of the 1970's-1980's for 1:250,000- or 1:100,000-scale quadrangles, compiled from aerial photography. The native digital format of the USGS LULC data is Geographic Information Retrieval and Analysis System (GIRAS). The LULC provided the original base of nationally consistent land use that was enhanced by users over the years and then finally was refined with more recent ancillary data on 1990 population to depict urban areas more representative of the 1990's.

    EPAGIRAS (source 2 of 3)
    U.S. Environmental Protection Agency (USEPA), 1994, Land use and land cover data digital data from 1:250,000- and 1:100,000-Scale maps, digital quadrangles converted to ArcInfo format: USEPA, Washington, DC.

    Online Links:

    Type_of_Source_Media: digital
    Source_Scale_Denominator: 250000
    Source_Contribution:
    The Environmental Protection Agency worked with USGS to convert the original LULC quadrangles from GIRAS format to ArcInfo Workstation coverages. After correcting minor errors in the coverages, the USGS NAWQA program used the EPAGIRAS data set in water-quality assessments during the mid-1990's.

    USPOPD90X10G (source 3 of 3)
    Price, Curtis, 20031124, 1990 population density by block group for the conterminous United States: USGS, Reston, VA.

    Online Links:

    Type_of_Source_Media: digital raster data
    Source_Scale_Denominator: 100000
    Source_Contribution:
    This data set provided a 100-m resolution ArcInfo Workstation grid (raster data set in which each cell is 100-m x 100-m) of 1990 population density by block group prepared using data from the 1990 Census of Population and Housing (P.L. 94-171 redistricting data) and 1990 TIGER/Line block group boundaries. Grid cell values represent population density in people per square kilometer multiplied by 10 so that the data could be stored as integer. The population data was used to enhance the older, less-detailed LULC land use data to represent urban areas more representative of the 1990's.

  2. How were the data generated, processed, and modified?

    Date: 2000 (process 1 of 6)
    During the early 1990's, USGS and the Environmental Protection Agency (USEPA) converted USGS LULC maps from GIRAS format to ArcInfo Workstation coverages. USEPA disseminated the ArcInfo Workstation coverages of LULC quads as ArcInfo export files (USEPA, 1994).
    During the mid- to late 1990's, the USGS NAWQA program downloaded coverages of LULC quads from USEPA and corrected many minor errors in the quads. NAWQA used this corrected set of quads for water-quality applications during the mid-1990's. However, many coding and topological errors still remained in the NAWQA version of the LULC coverages.
    During 2002-2003, NAWQA developed an enhanced LULC data set that was more accurate, topologically clean, and seamless. (For example, land use attribute errors were fixed and quad boundaries were matched.) Price and others (2003) describe the GIS processing steps to create the enhanced LULC data set. The enhanced version of LULC is the "best available" version of the historical USGS LULC data set.

    Date: 2003 (process 2 of 6)
    The ArcInfo Workstation seamless polygon coverage of enhanced LULC data was converted to a 30-m resolution ArcInfo Workstation grid (a raster data set in which each grid cell is 30-m by 30-m).

    Date: 28-Jan-2003 (process 3 of 6)
    The 30-m ArcInfo Workstation grid of the enhanced LULC data set (girasg) was refined using the 100-m resolution ArcInfo Workstation grid of 1990 Census block group population density using the methods described in Hitt (1994).
    Any area having a 1990 population density of at least 1,000 people per square mile (coded as 3,860 people per square km in the 100-m population density grid) that was not coded as urban or water in the LULC input data, was re-coded as "new residential" land use in the output data set. A numeric land use code of "10" was assigned to the "new residential" areas. This was accomplished using the following ArcInfo Workstation GRID commands:
    NEWLU90G = con ( ( girasg ge 11 and girasg le 17 ) or ( girasg ge 51 and girasg le 54 ) or ( girasg eq 0 ), girasg, con(uspopd90x10g ge 3860,10,girasg) )
    The resulting grid has 38 categorical values: 37 corresponding to the original Anderson level 2 land use land cover categories plus 1 for the "new residential" category. Because the quality of the output data is no better than the coarsest resolution of the input data (100 meters), the resolution of the output grid was set to 100 meters even though the resolution of the input LULC data grid was 30 meters. The ArcGIS software automatically resamples unequal input cell sizes to the output cell size.

    Date: 10-Jan-2005 (process 4 of 6)
    The grid was converted to a GeoTIFF image for distribution using the following ArcInfo Workstation command:
    gridimage newlu90g newlu90g.clr newlu90g tiff

    Date: 14-Mar-2005 (process 5 of 6)
    Data set was reviewed by Jacqueline Nolan, USGS, Reston, VA. (1/24/2005). Here is a summary of her comments, with responses to the comments in brackets:
    I think that you have everything well documented, and referenced and could not find any problems. My one area of concern is under the "Logical Consistency Report" section which described the earlier work. In this you state that the "new residential" areas in 2000 appear to be shrinking due to the changes in block group boundaries. Does this mean that the current grid represents the status quo for that timeframe; and if so, will there be any effort to recompute population using another Census Bureau parameter (if there is one)? [Added: "We do not plan to recompute population using another Census Bureau parameter." to the text.]
    Under Supplemental Information and under Entity and Attribute Overview for newlu90g, 386 people per square kilometer should read "3860" . [True, the values in the grid were multiplied by 1000, but the classification scheme remains the same, i.e., "residential" land is any area with population density of at least 1,000 people per square mile (386 people per square kilometer).]
    Under the Anderson Classification System - Code 2 Agricultural land, level 2 - Confined "feeeding" operations (misspelling) [Corrected spelling.]
    The overall grid looks good when viewed in ArcMap; colors are well chosen and coding is concise. I think you have created a very useful product.

    Date: 14-Mar-2005 (process 6 of 6)
    Data set was reviewed by Susan Buto, USGS, Carson City, NV. (1/26/2005) Here is a summary of her comments, with responses to the comments in brackets:
    1. General metadata
    a. I ran the metadata in both .xml and .met format through "mp" which found no errors in either file.
    b. I examined the metadata file that resides with the grid by opening it in ArcCatalog. I also exported it to a .txt file which I ran through mp. This file generated three errors as follows:
    i. mp 2.8.12 - Peter N. Schweitzer (U.S. Geological Survey) ii. Error (line 740): Process_Date is required in Process_Step iii. Error (line 743): Process_Date is required in Process_Step iv. Error (line 746): Process_Date is required in Process_Step v. 3 errors: 3 missing
    These errors occur because ArcCatalog records a process step when you import metadata or move the dataset. Either these process steps should be deleted so the "internal" metadata file is formatted to match the published version or the xml should be deleted from the coverage directory so you don't have to keep up with it. [Deleted the metadata.xml file that resides in the grid directory.]
    c. Our group is having an ongoing discussion regarding the use of the supplemental information section. We are split into two camps - those that think this section is a good place to put a narrative describing the process steps and any other information the author thinks is pertinent and those that think much of the information in this section is redundant. Since I am a member of the second camp, I think that everything that has nowhere else to go (how the grid is stored, how to unzip/untar it, and what the result of the unzip/untar process is) should be removed and placed in the purpose, abstract and process steps. This suggestion is absolutely subject to your interpretation. The FGDC includes no guidelines for the use of this section in the metadata workbook (<http://www.fgdc.gov/publications/documents/metadata/workbook_0501_bmk.pdf>). [No change to supplementary information.]
    d. I am unclear on the use of the term "Visual checks" in the completeness report (in data quality information). The FGDC metadata workbook suggests that the completeness report is used in "describing the relationship between the objects represented and the abstract universe of all such objects. In particular, the report shall describe the exhaustiveness of a set of features". I interpret this statement as an abstract way to say that the completeness report describes omissions from the data set. The completeness report should simply state that the data set is "complete for (some geographic area)" if there are no known omissions to report. [Changed to: "Complete for conterminous United States."]
    2. Spelling/Grammar/Usage
    a. In Keywords: The first theme keyword is inlandWaters - should that be inland waters? Is that really a primary theme? [The keyword "inlandWaters" is required for Geospatial One Stop indexing.]
    b. In the process description dated 20030128, your tense changes between paragraphs. Paragraph 1 is in past tense and paragraph 2 is in present tense. Your other process steps are in past tense. [Changed paragraph 2 to past tense.]
    c. In the process step dated 20050110, "commands" should be singular since there is only one. [Changed to singular.]
    d. You can put this comment in the category of "picky reviewer", but some of your descriptions of Anderson level 2 land use codes do not match the text in Anderson and others, 1976. This is true for: 14 - Transportation, communication, and utilities; 22 - Orchards, groves, vineyards, nurseries, and ornamental horticulture areas ; 73 - Sandy areas other than beaches; 75 - Strip mines, quarries, and gravel pits; 83 - Bare ground tundra. [All terms listed were corrected.]
    e. In your enumeration of land use codes - 11 - Residential, Residential is misspelled and in 23 - confined feeding operations, feeding is misspelled. [Spelling corrected.]
    3. Data Set and process steps
    a. The data set unzipped properly and as described in the metadata.
    b. The .vat and .sta tables were intact and display as described in the metadata.
    c. The color table works properly.
    d. Results of "describe", "list" and "items" in workstation correspond to the metadata descriptions.
    e. A spot check of grid cell values and inspection of the .vat yielded no unexpected values
    f. Overall, the process steps make sense and the discussion of changes to census block group boundaries and their effect on the data is clear and concise. However, I don't see a statement describing how you ended up with a 100 meter grid when you started with a 30 meter GIRAS grid developed from the enhanced LULC data in your first process step. The condition statement in the step dated 20030128 returns girasg or places the value 10 in the cells where the population density warrants it. Was girasg the 30 meter enhanced LULC grid you started with?
    [Added clarification to text: "Because the quality of the output data is no better than the coarsest resolution of the input data (100 meters), the resolution of the output grid was set to 100 meters even though the resolution of the input LULC data grid was 30 meters. The GIS software automatically resamples unequal input cell sizes to the output cell size."]

  3. What similar or related data should the user be aware of?

    Anderson, James R. , Hardy, Ernest E. , Roach, John T. , and Witmer, Richard E. , 1976, A land use and land cover classification system for use with remote sensor data: USGS Professional Paper 964, U.S. Government Printing Office, Washington, DC.

    Online Links:

    USGS, 1986, Land use and land cover data digital data from 1:250,000- and 1:100,000-scale maps, Data user guide 4: USGS, Reston, VA.

    Online Links:

    Hitt, Kerie J. , 1994, Refining 1970's land-use data with 1990 population data to indicate new residential development: USGS Water-Resources Investigations Report 94-4250, U.S. Geological Survey, Reston, Virginia.

    Online Links:

    Price, Curtis, Nakagaki, Naomi, Hitt, Kerie, and Clawges, Rick, 2003, Mining GIRAS: Improving on a national treasure of land use data: Proceedings of the ESRI International User Conference 2003, ESRI, Redlands, CA.

    Online Links:

    Gilliom, R.J., Alley, W.M., and Gurtz, M.E., 1995, Design of the National Water-Quality Assessment Program--Occurrence and distribution of water-quality conditions: USGS Circular 1112, USGS, Reston, VA.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    Not checked.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Complete for conterminous United States.

  5. How consistent are the relationships among the observations, including topology?

    The data set was spot checked with the 100-m source grid of enhanced LULC and a similar derivative product consisting of a 100-m grid of LULC updated with 2000 population.
    Some logical assumptions are that areas that were "new residential" urban land in 1990 would not revert to another land use in 2000 and that "new residential" areas would expand from 1990 to 2000. However, between 1990 and 2000, some Census block group boundaries changed, and population density shifted. As a result, some areas considered to be "new residential" in 1990 no longer are considered to be "new residential" in 2000. In some places, areas of "new residential" appear to be shrinking in 2000 because of the different block group boundaries. Population density in part of the area that used to be considered new residential is less than the population density threshold value in 2000. We do not plan to recompute population using another Census Bureau parameter.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None.
Use_Constraints: This data should not be used at scales smaller than 1:250,000.

  1. Who distributes the data set? (Distributor 1 of 1)

    U.S. Geological Survey
    Ask USGS - Water Webserver Team
    507 National Center
    Reston, VA 20192
    USA

    1-888-275-8747 (1-888-ASK-USGS) (voice)
    <http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+newlu90g>

  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    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.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 14-Mar-2005
Metadata author:
U.S. Geological Survey
Ask USGS - Water Webserver Team
507 National Center
Reston, VA 20192
USA

1-888-275-8747 (1-888-ASK-USGS) (voice)
<http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+newlu90g>

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata ("CSDGM version 2") (FGDC-STD-001-1998)


Generated by mp version 2.9.6 on Wed Apr 10 12:34:14 2013