The contributions of satellite-based remote sensing to the mapping of evapotranspiration (ET) and water resource trends over large geographic regions are being increasingly recognized. Researchers are relying on remote sensing tools such as OpenET to help analyze data and improve water resources management and monitoring. The accuracy of this modeling platform was recently gaged for different crops and land cover classifications by comparing ET data from OpenET with that produced by 152 ground-based micrometeorological stations.

The findings published in Nature Water confirm the accuracy of OpenET data for assessing evapotranspiration in agricultural settings. Trends documented for wheat, corn, soy and rice crops were highly reliable and accurate in arid regions like California and the southwestern U.S., supporting the use of this tool to address ongoing regional water sustainability issues.

“Evapotranspiration is one of the hardest hydrologic fluxes to measure, and to think we are quantifying this flux from space with comparable or better accuracy to ground-based weather stations and meter data for agricultural lands is really remarkable,” said study co-author Justin Huntington of the Desert Research Institute. “The combined use of the Landsat-satellite archive with new Google Earth Engine cloud computing resources has been key, as has our collaboration across different research groups and use of multiple models to better understand model strengths and weaknesses and identify areas for improvement.”

Continuing research will focus on natural ecosystems and how OpenET models compare under different agricultural demand management and conservation actions such as those being explored in the Colorado River Basin.

Researchers from NASA Ames Research Center, University of Idaho, the U.S. Department of Agriculture Agricultural Research Service, University of California-Los Angeles, University of Nebraska-Lincoln, Universidade Federal do Rio Grande do Sul (Brazil), U.S. Geological Survey Earth Resources Observation and Science Center, KBR Inc., NASA Marshall Space Flight Center, NASA Jet Propulsion Lab, University of California-Berkeley, Innovate! Inc. and Mississippi State University also contributed to this study.