Estimating 2017 groundwater withdrawals for agricultural water use In Arizona

Ammon Cadogan and Martha Whitaker

Hydrology and Atmospheric Sciences
The University of Arizona

Crops grown in Arizona are found in grocery stores across the nation. With low levels of rainfall and high heat, groundwater is essential for the survival of agricultural plants and humans in Arizona.  The goal of this project was to estimate groundwater withdrawals for agricultural use in several basin defined by Arizona Department of Water Resources in 2017. Withdrawals were calculated by multiplying crop consumptive use by field acreage then dividing by the corresponding irrigation efficiencies. Crop and irrigation efficiency data was collected via in situ visits and remote sensing methods. Crop consumptive use data was calculated using Prism Climate Group data (NACSE, 2017) with the Modified Blaney-Criddle equation. Total withdrawal values for 2017 ranged from 253,000 to fewer than 1,000 acre feet. The Gila Bend watershed used the most water (253,000 acre feet) followed by Willcox (208,000 acre feet) and Lower Gila (121,000 acre feet) watersheds. Compared with previous years’ data, most of the basins show a trend of decreasing water use, indicating smarter irrigation practices and more strict regulations. This information has the potential to educate the public and help managers make more informed decisions with regard to the state’s diminishing water resources.

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