1. Abstract U.S. Geological Survey, 1990. Land use and land cover digital data from 1:250,000- and 1:100,000-scale maps. Data User Guide 4. Reston, Virginia. Descriptors: GIS, digital spatial data, land use, land cover, GIRAS 2. Applications that use this data Land use and land cover data LU/LC collected by the USGS NMD is useful for environmental assessment of land use patterns with respect to water quality analysis, growth management, and other types of environmental impact assessment. 2.1 Intended use of data Data are meant to be used by quadrangle, or among adjacent quadrangles where temporally contiguous. Can be used in any geographic application where intermediate scale land use data are appropriate and the dates are representative. 2.2 Limitations of data Each quadrangle of land use data has a different representative date. Date ranges from mid 1970s to early 1980s are common. When joined together these quadrangles will not likely match along edges due to differences in interpretation and time coverage. Edges of each map file were manually digitized and may not join neighboring maps. If GIRASNEAT program has been applied (see LOG at end) then edges have been mathematically recalculated to join without overlap or gaps in coverage with adjacent maps. 3. Attribute discussion The GIRAS series can include several themes of spatial data. The most common, described here, is the land use and land cover data. Land use was mapped and coded using the Anderson classification system (Anderson and others, 1976) which is a hierarchical system of general (level 1) to more specific (level 2) characterization. Some agencies have taken this to a level 3 classification -- but this has not been done in the GIRAS series. The salient attribute managed for this polygon data set in the polygon attribute table (PAT) is the column named LUCODE containing the Anderson level 2 classification. The first digit represents the level one value and the second digit (ones place) represents the subdivision of the level 1 or level 2 value. The Anderson land use codes are: Level 1 Level 2 ------- ------- 1 Urban or built-up land 11 Residential 12 Commercial and services 13 Industrial 14 Transportation, communication, 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 feeeding operations 24 Other agricultural land 3 Rangeland 31 Herbaceous rangeland 32 Shrub and brush rangeland 33 Mixed rangeland 4 Forest land 41 Decisuous 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 not beaches 74 Bare exposed rock 75 Strip mines, quarries, gravel pits 76 Transitional areas 8 Tundra 81 Shrub and brush tundra 82 Herbaceous tundra 83 Bare ground 84 Wet tundra 85 Mixed tundra 9 Perennial snow or ice 91 Perennial snowfields 92 Glaciers 4. Procedures used to create or automate data GIRAS files are received by the USGS or EPA in 9-track ASCII format, one file per quadrangle. Files are loaded onto the hard disk of the computer from tape. Data are then processed with the GIRASARC2 program written in Arc Macro Language, part of the ARC/INFO geographic information system. This program was written by the USGS Water Resources Division to process GIRAS data into a consistent ARC/INFO format with a minimum of intervention. This GIRASARC2 AML program does the following: -- Converts the GIRAS data to ARC/INFO -- Reconstructs topology, creating line and polygon features -- Transforms the coverage into UTM and then, optionally into Albers Equal Area, using the registration points listed in the GIRAS file -- Notes transformation error, writing it to the bottom of the narrative file -- Generates a synthetic neatline based on the mathematically-determined corners of the map -- Loads available documentation into a series of companion documentation files with each data set. -- Data may then be clipped against or extended to the synthetic neatline for ease in merging adjacent maps at a later date 5. Revisions made to data (revision number, date, description) 1.0 Original conversion from GIRAS to ARC (see LOG for date and user ID) 6. Reviews applied to data (review type, date, person, description) Data are reviewed visually by the user responsible for executing the GIRASARC2 program. 7. Related spatial and tabular data sets and programs The GIRASARC2 and GIRASNEAT programs were executed in Arc Macro Language to create this data set. The DOCUMENT AML (version 0.9.9) was used to manage the documentation 8. References cited Anderson, J.R., Hardy, E.E. Roach, J.T. and Witmer, R.E., 1976, A land use and land cover classification system for use with remote sensor data: U.S. Geological Survey Professional Paper 964, 28 p. U.S. Geological Survey, 1990. Land use and land cover digital data from 1:250,000- and 1:100,000-scale maps. Data User Guide 4. Reston, Virginia. 9. Notes Example Map Header Information from GIRAS file ---------------------------------------------------------- title: ROANOKE, VA 1:250,000 QUAD LAND USE MAP file creation date: 83332 map type: 1 projection: 1 scale: 1:393701 source materials date: 1974 number of map sections: 24 ---------------------------------------------------------- Report of error in coordinate transformation: ------------------------------------------------------------------------ Transforming coordinates for coverage tmpcov Scale (X,Y) = (10.000,10.000) Translation = (499985.008,3999975.038) Rotation (degrees) = (0.007) RMS Error (input,output) = (1.343,13.431) tic id input x input y output x output y x error y error ------ ---------------- ---------------- ---------------- ---------------- 1 8899.000 9516.000 588979.500 4095136.500 6.276 11.648 2 8779.000 20607.000 587800.625 4206081.000 -1.007 -18.701 3 17559.000 20751.000 675607.750 4207496.500 -9.033 15.168 4 26343.000 20985.000 763427.938 4209857.500 9.990 3.575 5 26697.000 9886.000 766968.625 4098877.500 -4.579 -10.331 6 17797.000 9654.000 677966.500 4096539.000 -1.647 -1.360