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Estimated crop irrigation water use withdrawals in Lower San Pedro Groundwater Basin, Arizona for 2020

April 21, 2022

Observations of irrigated agricultural land within the Lower San Pedro Groundwater Basin in Arizona. Crops were verified in situ once in 2020 on July 14th; based on digitized field boundaries. Field boundaries were digitized from U.S. Department of Agriculture, National Agricultural Imagery Program images dated 2019 and supplemented with Landsat and Sentinel2 imagery collections accessed via the U.S. Geological Survey LandLook Viewer ( and Sentinel Hub, Sentinel Playground ( Satellite images were also used to identify the length of the growing season and crop condition. Water withdrawals were calculated using the modified Blaney-Criddle model of calculating consumptive use (U.S. Bureau of Reclamation, 1992 appendix A) using crop coefficients from Doorenbos and Pruitt (1975), the number of acres with active crops, crop condition, and irrigation system efficiency. The withdrawal equation was modified from "Water withdrawals for irrigation, municipal, mining, thermoelectric-power, and drainage uses in Arizona outside of active management areas, 1991-2000" (Tadayon, 2005) to account for variations in water application. Data are available as a shapefile for visualization or as a stand-alone csv table for attributes only.

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