Scientific Developments in Quantifying Consumptive Use and Crop Water Requirements for Washington State

This research highlight advances the quantification of crop water requirements and consumptive use across Washington state. The project developed a new statewide database of crop water requirements using updated methods and expanded datasets, replacing outdated paper-based estimates. The database is publicly available through an online tool that supports water right planning, irrigation system design, scheduling, and hydrologic modeling.

The research also adapted the METRIC evapotranspiration (ET) model for drone-based imagery, substantially improving spatial and temporal resolution compared to satellite imagery. Drone-based ET estimates were validated against satellite estimates and shown to produce comparable results while enabling field-level management insights.

Additional work examined whether microclimate cooling from sprinkler irrigation reduces downstream crop water demand. While sprinkler losses slightly reduced evapotranspiration (about 1%), the effect did not offset measured water losses of approximately 30% due to wind drift and evaporation. The study also evaluated portable artificial hot and cold reference surfaces for improving drone-based ET estimation accuracy.

This work was supported by the USDA National Institute of Food and Agriculture, project #1016467.