Percent of Hydrologic Unit in Developed Land, 1997
Description
This polygon map shows developed land as a
percentage of total surface area of each 8-digit
hydrologic unit. Developed land is a
combination of land cover/use categories, Urban
and built-up areas, and Rural transportation
land. Areas with 95% or more Federal area are
shaded gray.
Cautions for this Product:
Use this map only to identify broad spatial
trends. Data are not collected on Federal land.
Data are not available for Alaska or the Pacific
Basin. Data for Puerto Rico and the U.S. Virgin
Islands is shown by 6-digit hydrologic unit.
Sources
Source:
National Resources Inventory, 1997
Distributor:
USDA-NRCS-RIAD
Reliability:
NRI sample data are generally reliable at the
95% confidence interval for state and certain
broad substate area analyses. Generally,
analyses that aggregate data points by smaller
geographic areas and/or more specific criteria
result in fewer data points for each aggregation
and therefore less reliable estimates. NRI maps
reflect national patterns rather than site-
specific information.
Layers
Aggregate Layer:
8 Digit Hydrologic Unit Areas with Federal Land
Other Layers Displayed:
States, Rivers
Definitions
Developed land:
A combination of land cover/use categories,
Urban and built-up areas, and Rural
Transportation Land.
Hydrologic units:
A hierarchical system developed by the U.S.
Geological Survey that divides the United States
and the Caribbean into 21 major regions, 222
subregions, 352 accounting units, and further
subdivided into 2,150 cataloging units that
delineate river basins having drainage areas
usually greater than 700 square miles. [USGS]
Rural transportation land:
A Land Cover/Use category which consists of all
highways, roads, railroads and associated rights-
of-way outside urban and built-up areas;
including private roads to farmsteads or ranch
headquarters, logging roads, and other private
roads, except field lanes. [NRI-97]
Urban and built-up areas:
A Land Cover/Use category consisting of
residential, industrial, commercial, and
institutional land; construction sites; public
administrative sites; railroad yards;
cemeteries; airports; golf courses; sanitary
landfills; sewage treatment plants; water
control structures and spillways; other land
used for such purposes; small parks (less than
10 acres) within urban and built-up areas; and
highways, railroads, and other transportation
facilities if they are surrounded by urban
areas. Also included are tracts of less than 10
acres that do not meet the above definition but
are completely surrounded by Urban and Built-up
land. Two size categories are recognized in the
NRI: (i) areas 0.25 to 10 acres, and (ii) areas
greater than 10 acres. [NRI-97]
Product Information
Product ID:
5089
Production Date:
12/13/00
Product Type:
Map
For additional information
contact the Resources Inventory and Assessment Division.
Please include the Product ID you are inquiring about.
nri@wdc.usda.gov
or 1400 Independence Avenue SW - P.O. Box 2890 -
Washington D.C. 20013. If you use our analysis products,
please be aware of our disclaimer.
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