Remotely sensed evapotranspiration for corporate water stewardship: Opportunities and limitations in agricultural landscapes

Sam Zipper , Rachel O'Connor, Gopal Penny, Derek Schlea, Garshaw Amidi-Abraham, Simone Schenkel, Maurice Hall

Corporate water stewardship (CWS), in which companies engage in or incentivize actions to advance sustainable water resource management, can positively affect water resources, reduce water-related business risks, and support Environmental, Social, and Governance (ESG) and sustainability reporting efforts. Agricultural landscapes affect diverse industries including finance, technology, fuel production, insurance, and food/beverage companies but distributed agricultural supply chains make quantifying water use and impacts of CWS activities difficult. Here, we discuss opportunities and limitations of remotely sensed evapotranspiration (ET, the transfer of water vapor from the land surface into the atmosphere) data for CWS applications in agricultural landscapes. First, we identify five key principles for hydrologic analysis to support effective CWS: variables should be scientifically-appropriate, actionable, spatially consistent but locally tailored, impact-focused at a relevant operational scale, and reproducible and verifiable. Remotely sensed ET has potential relevance for many CWS activities including understanding risks, setting corporate commitments, quantifying historic conditions, and outcome monitoring/reporting. Most directly, remotely sensed ET methods provide a reproducible and verifiable input for calculating consumptive water use, which is the total ET of a crop within a period of time such as a growing season and is often related to total agricultural water use. Calculating irrigation applications and/or withdrawals requires accounting for additional processes beyond ET and therefore involves additional modeling or monitoring approaches. There are many opportunities for remotely sensed ET to be useful for CWS, as long as care is taken to focus on suitable applications and communicate uncertainty.