Dominant Cropland Irrigation Water Source, 1997
Description
This shaded polygon map shows the dominant water
source for irrigated cropland for each 8-digit
hydrologic unit. Water sources are categorized
by 1) Well, 2) Pond, Lake, or Reservoir, 3)
Stream, Ditch, or Canal, 4) Lagoon or Wastewater
(not tailwater), and 5) a combination of water
sources. The dominant water source is defined as
the water source that is the most common in that
hydrologic unit. Areas with 95% or more Federal
area are shown as gray. Areas without irrigated
cropland are left white.
Cautions for this Product:
In many areas shown on this map as irrgated, non-
irrigated cropland may be more common than any
type of irrigated cropland. The total amount of
irrigated cropland may be small. Irrigation of
land uses other than cropland is not included.
Data are not collected on Federal land. Data
are not available for Alaska, and the Pacific
Basin. Data for Puerto Rico and the U.S. Virgin
Islands are 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
Canal:
An artificial waterway used for irrigation. [NRI-
97]
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]
Ditch:
A long, narrow trench or furrow dug in the
ground, as for irrigation. [NRI-97]
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]
Irrigated land:
Land that shows evidence of being irrigated
during the year of the inventory or during two
or more years out of the last four years. Water
is supplied to crops by ditches, pipes, or other
conduits. Water spreading is not considered
irrigation; it is recorded as a conservation
practice. [NRI-97]
Lagoon - waste treatment:
An impoundment made by excavation or earthfill
for biological treatment of animal or other
agricultural waste. [NHCP]
Lake:
An inland body of water (fresh or salt) of
considerable size occupying a basin or hollow on
the earth's surface, and which may or may not
have a current or single direction of flow.
[ASCE- "Nomenclature for Hydraulics"]
Stream:
A flow of water in a channel or bed, as a brook,
rivulet, or small river. [NRI-97]
Well:
A hole drilled or bored into the earth providing
access to water. [NRI-97]
Product Information
Product ID:
5307
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.
| 
About Us
Map 5307 - PDF
Map 5307 - Postscript
Back to Top