Efficient agriculture water use is of crucial importance for water resources management. Evapotranspiration is an important part of the water cycle, as it is the sum of evaporation and plant transpiration from the Earth's land and ocean surface to the atmosphere. Consequently, accurately determining evapotranspiration (ET) is the first step for improving irrigation efficiency and productivity and for quantifying the ecosystem water balance. The IRIDA´s approach is to combine on the ground ET and soil moisture measurements, with remote sensing ET determinations obtained with unmanned aerial vehicle (UAV/RPAS/UAS) (at plot scale) and manned vehicles and satellites (at catchment scale). More