Annual Groundwater Withdrawals By Agriculture In The Willcox Basin, 2023
Presenter: Dylan Simpson P211
Co-Author(s): Dylan Simpson, Amy Read, Tom Porter, Abigail Kahler
Advisor(s): Martha Whitaker
1Hydrology & Atmospheric Sciences
The Willcox Groundwater Basin is a highly-active farming region in southeastern Arizona near the borders of New Mexico and Mexico. Its aquifer receives minimal recharge from precipitation (13 in/year) yet farming in Cochise County has continued to increase over the century as population growth demands more agricultural resources. In response to over-pumping the basin has undergone substantial and irreversible subsidence: sections of the basin have subsided almost 10 feet in the past 50 years. To estimate the yearly withdrawal from the Willcox aquifer various properties of the agriculture fields were gathered. To gather properties of various fields such as crop type, area, and length of the growing season, infrared satellite imagery was coupled with physical field visits throughout the year. In addition to observing and recording types of crops, field visits were crucial in understanding variables such as irrigation type and irrigation efficiency that play a role in the overall withdrawal. PRISM (Parameter-elevation Regressions on Independent Slopes Model) data are used to integrate weather conditions such as precipitation and temperature. Some field properties and weather data were used in a modified Blaney-Criddle model to estimate annual consumptive use, additional field properties were used to estimate groundwater withdrawals in 2023. Previous years’ estimates of total withdrawal throughout the Willcox Basin were around 200,000 ac-ft for 2020 and 150,000 ac-feet for 2022.