Assessment of reference evapotranspiration using remote sensing and forecasting tools under semi-arid conditions

Once calibrated and validated, and thanks to the use of remotely sensed data, the MAK-Adv approach allowed the ETo assessment at regional scale. For a semi-arid region located in southern Spain with an area of 87,300 km2, a detailed spatial ETo assessment was performed, determining ETo values for the totality of the area with a resolution of about 9 km2 allowing to evaluate the spatial and temporal variability at basin/region scale. This new approach gets over the serious limitations for a correct ETo assessment when traditional methodologies are not able to provide these data for vast areas, even with the modern weather station networks. Thus, MAK-Adv approach is especially useful for those areas with missing or inaccurate meteorological in situ observations.