National Land-Cover Characteristics Data: Refinement for the Platte River
By R.B. Zelt(1) and J.F. Brown(2)
Land cover affects the quality of aquatic ecological resources at a variety
of scales--from localized effects of chemical applications on lawns and
cropland to regional atmospheric deposition of agricultural pesticides, as
examples. The U.S. Geological Survey (USGS) is interested in quantifying the
land-cover characteristics of surface-drainage basins being studied as part
of its National Water-Quality Assessment Program. Through a collaborative
effort between scientists at the University of Nebraska-Lincoln (UNL) and at
the USGS EROS Data Center, Sioux Falls, South Dakota, digital spatial data
for land-cover characteristics of the conterminous United States were
developed. The data were derived from digital imagery collected on multiple
dates throughout the 1990 growing season by a weather-satellite sensor (the
Advanced Very High Resolution Radiometer). Data refinement was made on the
basis of other national data sets that included elevation, climate, soils,
and ecological regions. Because the labeling of land-cover categories was
optimized at the national level, the utility of the data for regional studies
potentially could be improved through refinement of the category labels on
the basis of localized information.
During the summer of 1993, investigators from UNL and USGS recorded land-cover
observations at 210 1-km2 sampling locations in the Platte River
Basin (portion below North Platte, Nebr.) to evaluate the corresponding part
of the national land-cover characteristics data and to refine it specifically
for the 78,000-km2 basin. Sampling locations were selected using
a stratified-random procedure that included statistically adequate numbers of
samples from six generalized land-cover categories--row crops, mixed crops,
grass, grass/crops, woods/crops, and woods/grass. The percentage of each
1-km2 sampling location that was covered by each of 11 specific
land-cover categories (5 major crops, grass, woods, emergent vegetation, open
water, buildings, and barren) was recorded.
- U.S. Geological Survey, 4821 Quail Crest Place,
Lawrence, KS 66049.
- Conservation and Survey Division, University of
Nebraska-Lincoln, Lincoln, NE 68588. The UNL participation was funded by U.S.
Environmental Protection Agency grant X007526-01.
Zelt, R.B., and Brown, J.F., 1993, National land-cover characteristics data--Refinement
for the Platte River Basin, Nebraska [abs.]: Platte River Basin Ecosystem Symposium,
Grand Island, Nebr., 1993, Program and Abstracts, p. 6.