Satellite Mapping of Agricultural Water Requirements in California with the Terrestrial Observation and Prediction System

Satellite mapping of evapotranspiration (ET) from irrigated agricultural lands can provide water managers and agricultural producers with information that can be used to optimize agricultural water use, especially in regions with limited water supplies. In particular, the timely delivery of information on agricultural crop water requirements has the potential to make irrigation scheduling more practical, convenient, and accurate. We present findings from the development and deployment of a prototype system for irrigation scheduling and management support in California. The system utilizes the NASA Terrestrial Observation and Prediction System to integrate satellite observations and meteorological observations to map crop canopy development, basal crop coefficients (Kcb), and evapotranspiration (ETcb) values for multiple crop types in the Central Valley of California at the scale of individual fields. Information is distributed to agricultural producers and water managers via a web-based irrigation management decision support system and web services. We present the prototype system, including comparisons of estimates of ETcb from the prototype system against estimates of ET from other methods, including surface renewal stations and observations from wireless sensor networks deployed in operational agricultural fields across California. We discuss the potential for integration of ET from energy balance models to support near real-time mapping of consumptive water use and crop water stress.