New assessment of OpenET accuracy points to expanding, vital role of satellite-based water management tools

(SACRAMENTO, CA - January 23, 2024) — The satellite-based water data platform OpenET demonstrates considerable accuracy in measuring evapotranspiration in agricultural settings according to a new study in Nature Water. Evapotranspiration—the amount of water lost to the atmosphere through soil evaporation and plant transpiration—is a key measure of water consumption in agriculture and has previously been difficult and expensive to monitor accurately at scale.  

A public-private collaboration led by NASA, California State University Monterey Bay, Environmental Defense Fund, Desert Research Institute, and HabitatSeven, OpenET uses publicly available data produced by NASA and USGS Landsat and other satellite and ground-based systems to calculate evapotranspiration rates at the field level. The study shows OpenET’s results are particularly reliable for arid regions like California and the Southwest and for annual crops like wheat, corn, soy, and rice. The findings highlight the increasing value of OpenET in supporting real-time agricultural water management in regions hardest hit by growing water scarcity. 

“Farmers and water managers increasingly need accurate, field-level data on water use,” said Maurice Hall, OpenET director and senior advisor, Climate Resilient Water Systems, Environmental Defense Fund. “As reflected in the author list, this study is built on decades of work and helps confirm the vital role OpenET plays in providing a more granular, dynamic picture of water use that can meaningfully inform real-time water decision-making. We look forward to continuing to refine and expand the implementation of OpenET, to ensure farmers, ranchers, and communities can thrive in a world of highly stressed and variable water supplies.” 

“It’s truly rewarding to see decades of careful research and hard work by this science community come together, and this study sets a new benchmark for satellite mapping of field-scale evapotranspiration with Landsat,” said Forrest Melton, senior research scientist with NASA Ames Research Center. “By documenting the accuracy of the OpenET data, I anticipate that this study will further accelerate the already rapid uptake and use of these data to help solve pressing water management challenges and open up new applications and areas of future study.” 

In a supplementary article also published in the same edition of Nature Water, researchers argue, “OpenET shows promise towards a more sustainable way of water use,” by providing farmers with, “information that can potentially help them reform irrigation scheduling and increase water use efficiency, thereby conserving water and saving money.” 

Members of OpenET’s growing user base have also voiced their support for the platform’s accuracy and efficacy:

“The OpenET portal has enabled the Upper Colorado River Commission to evaluate water use from field- to basin-scale in a more efficient, cost-effective, and timely way,” said Sara Larsen, Deputy Director and Chief Engineer of the UCRC. “It has enabled us to fairly evaluate and administer our ongoing interstate water conservation programs such as the System Conservation Pilot Program. These programs work to benefit and protect critical infrastructure in the Upper Basin, as well as to increase local resiliency to drought and climate change. The OpenET Platform and the science behind it are core components of our ongoing efforts.”

The full study is available here.

OpenET was developed through an unprecedented public-private collaboration with input from more than 100 farmers, water managers, and other stakeholders. OpenET is led by NASA, California State University Monterey Bay, Environmental Defense Fund, Desert Research Institute, and HabitatSeven. Additional team members include Google, U.S. Geological Survey, U.S. Department of Agriculture, California State University Monterey Bay, University of Idaho, University of Maryland, University of Nebraska-Lincoln, University of Wisconsin-Madison, UCLA, and Universidade Federal do Rio Grande do Sul in Brazil.