Comparison of Consumptive Water Use Methodologies at Farm Scale Using Ground and Remote Sensing Information in Modena, UT

As increasing drought events threaten water resources, the estimation of evapotranspiration (ET) becomes an increasingly important component of water resource management. Technological advancements are improving access to water use data; however, the variations in results from the different methods pose the question of which one best balances accuracy, efficiency, and accessibility. This research aims to evaluate and recommend methods for estimating crop water use in sprinkler-irrigated corn and alfalfa fields based on results from soil moisture methods, satellite imagery, irrigation flow meters, and state recommended consumptive use for the 2021 growing season in Modena, UT. Daily ET estimates from soil moisture data were estimated using three versions of the soil moisture depletion and slope methods. Monthly ET estimates from satellite imagery were retrieved from the OpenET platform [www.openetdata.org]. The state recommended consumptive water use was retrieved from the Crop and Wetland Consumptive Use and Open Water Surface Evaporation for Utah report. The comparison of results from the methods shows that, in general, the State of Utah recommendations are larger than the monthly crop water use from the other methods. The intercomparison of methodologies shows no consistent significant differences between the ET estimates from the soil moisture methods and the ET measurements from OpenET. Comparison to the irrigation flow meter readings indicates a reasonable correlation between the applied water and the crop water use. This comparison also highlights the effort necessary to generate information based on the evaluated methodologies