Satellite-Based Remote Sensing Approaches for Estimating Evapotranspiration from Agricultural Systems

Quantifying the actual amount of water used by agricultural cropping systems is deemed essential for irrigation scheduling and management. Conventionally, this has been either not pursued or done using single-point measurement or estimation tools. Since crop water uses may vary spatially within the field and over time, understanding its spatiotemporal dynamics has emerged as a critical need for sustainable agricultural production. To address this, satellite-based remote sensing (RS) has evolved as a rapid and high-throughput tool for mapping geospatial evapotranspiration (ET) from agricultural production systems, globally. Such data is either used through various biophysical models or empirical data-run approaches towards improving the accuracy of ET estimates which are deemed to serve as decision support for precision irrigation and water management. This chapter discusses fundamentals of computing ET through various energy balance and empirical models that have evolved or refined over time. The chapter also summarizes up-to-date case studies with identified accuracies of water use estimations using satellite-based RS approaches. Such approaches demonstrate potentials to be coupled with automated irrigation systems for envisioned precision irrigation scheduling and management at spatiotemporal scales.