Change in Average Annual Soil Erosion by Wind on Cropland and CRP Land, 1982 - 1992
Description
This shaded polygon map shows the change in the
average annual rate of soil erosion by wind in
tons per acre per year on cropland and
Conservation Reserve Program (CRP) land between
1982 and 1992. The average annual Wind Erosion
Equation (AAWEQ) is used to determine annual
erosion rates. Data are aggregated by 8-digit
hydrologic unit areas. Areas where cropland and
CRP land occupy less than 5% of the total area
are hatched. Areas with 95% or more Federal area
are shaded gray. There was a net decrease of 1.0
tons per acre per year between 1982 and 1992. This map replace map #2754.
Cautions for this Product:
Since cropland and CRP land may occupy only a
small percentage of the total area of some of
the polygons, the map may leave a misleading
impression as to the higher erosion rates in
some areas. Note that no CRP land was recorded
in 1982, since the program did not begin until
the mid-1980s. Data are not shown where cropland
and CRP are less than 5% of the total area. 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
Conservation Reserve Program (CRP):
A Federal program established under the Food
Security Act of 1985 to assist private
landowners to convert highly erodible cropland
to vegetative cover for 10 years. [NMCSP]
Cropland:
A Land cover/use category that includes areas
used for the production of adapted crops for
harvest. Two subcategories of cropland are
recognized: cultivated and noncultivated.
Cultivated cropland comprises land in row crops
or close-grown crops and also other cultivated
cropland, for example, hayland or pastureland
that is in a rotation with row or close-grown
crops. Noncultivated cropland includes permanent
hayland and horticultural cropland. [NRI-97]
Erosion:
The wearing away of the land surface by running
water, waves, or moving ice and wind, or by such
processes as mass wasting and corrosion
(solution and other chemical processes). The
term "geologic
erosion" refers to natural erosion processes
occurring over long (geologic) time spans.
"Accelerated
erosion" generically refers to erosion that
exceeds what is presumed or estimated to be
naturally occurring
levels, and which is a direct result of human
activities (e.g., cultivation and logging).
[NSSH-96]
Wind erosion:
The process of detachment, transport, and
deposition of soil by wind. [NAM]
Wind erosion equation (WEQ):
An erosion model designed to predict long-term
average annual soil losses from a field having
specific characteristics (NAM). E= f(IKCLV)
where E is the estimated average annual soil
loss expressed in tons per acre per year; I is
the soil erodibility; K is the soil ridge
roughness factor; C is the climatic factor; L is
the equivalent unsheltered distance across the
field along the prevailing wind erosion
direction; and V is the equivalent vegetative
cover. [NAM]
Product Information
Product ID:
5066
Production Date:
12/7/00
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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