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Percent of Irrigated Cropland in Pressure Irrigation, 1992

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Description

This shaded polygon map shows the percent of irrigated cropland in pressure irrigation for each 8-digit hydrologic unit. Areas with 95% or more Federal area are shown as gray. There were 24.9 million acres of pressure irrigated cropland in the U.S. in 1992.

Cautions for this Product:
This map does not show the total amount of pressure irrigated Cropland. 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

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]

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]

Pressure irrigated:
Water is delivered to the farm and/or field in pump or elevation induced pressure pipelines; and water is distributed across the field by: [NRI-97] 1. Sprinkle irrigation (center pivot, linear move, traveling gun, side roll, hand move, big gun, or fixed set sprinklers), or, 2. Micro irrigation (drip emitters, continuous tube bubblers, micro spray or micro sprinklers).

Product Information

Product ID: 6013
Production Date: 5/23/01
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.