Fusion of Spatio-Temporal Remotely Sensed Evapotranspiration by Data Assimilation for Irrigation PerformanceMonitoring of water consumption in irrigation systems is paramount to integrated water management. This is already possible with Low spatial resolution (LSR) satellite remote sensing. However, smaller pixel size is still required for more local management, while keeping return period within few days. High spatial resolution (HSR) satellite imagery is indeed available for calculation of evapotranspiration, and has been used in many studies already.