<URL:http://water.usgs.gov/nawqa-only/gw.html>
This data set consists of NLCDE landcover category for NAWQA sampling sites. The NLCDE data is from the 1990's vintage NLCD 30-m data enhanced with GIRAS data. The sampling sites are from the NAWQA data warehouse.
This is one of the ancillary GIS data layers developed to characterize NAWQA sampling sites for national synthesis of water-quality data.
This data set excludes Alaska and Hawaii.
The original NLCD land cover data does not portray some land-cover categories very well:
1) Orchards are underrepresented, especially in the east. This is apparent when comparing NLCD and 1992 Census of Agriculture county totals.
2) Alpine tundra is not represented at all in NLCD.
3) Transportation is lumped with commercial and industrial or is not captured at all in NLCD.
4) Residential areas (especially mature residential areas) are often misclassified as forest, grassland or agriculture in NLCD.
Ancillary data layers from GIRAS were used to modify NLCD by burning in certain land cover data from GIRAS to the NLCD land cover map. We decided against using TIGER roads data because of coding errors in the TIGER attribute data (August 2003).
GIRAS data provided: Orchards/Vineyards Tundra (alpine areas) ResidentialSpecific rules were followed to preserve as much information as possible in the result.
CHANGE NLCD TO: WHEN: PRESERVE NLCD WHEN NLCD IS:
Orchard GIRAS is Orchard Water, Urban,
and state is not Orchard, Urban Grasses
CA, FL, OR, WA
Tundra GIRAS is Tundra and Any category except
NLCD is Shrubland Shrubland and
or Herb. Grassland Herbaceous Grassland
Residential w/ forest GIRAS is Residential Water, Urban,
and NLCD is forest Urban Grasses, Wetlands
Residential w/o forest GIRAS is Residential Water, Urban,
and NLCD is not forest Urban Grasses, Wetlands
Intersected sampling points with enhanced NLCD attributes using IDENTITY. (March 2004 version of NAWQAPT.)
Intersected sampling points with enhanced NLCD attributes using IDENTITY. (May 2004 version of NAWQAPT.)
The data set is organized by STAID (station id).
The fields are:
STAID Station id NLCDE NLCDE land use codeThe explanations for NLCDE codes:
NLCDE EXPLANATION CODE 11 Open Water 12 Perennial Ice/Snow 21 Low-Intensity Residential 22 High-Intensity Residential 23 Commercial/Industrial/Transportation 25 Residential without trees (GIRAS) 26 Forested Residential (Res-GIRAS, For-NLCD) 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 Orchards/Vineyards (GIRAS) 71 Grasslands/Herbaceous 72 Tundra (GIRAS) 81 Pasture/Hay 82 Row Crops 83 Small Grains 84 Fallow 85 Urban/Recreational Grasses 91 Woody Wetlands 92 Emergent Herbaceous Wetlands -999 No data (AK, HI, Canada)
kjhitt@usgs.gov
kjhitt@usgs.gov