Improving satellite estimation of actual evapotranspiration using field monitoring and crop simulation

Water is a natural resource that is in shortage in many areas of the planet. This fact will be exacerbated in the context of the climate crisis. Agriculture is the major consumer of water in Greece but at the same time an important polluter of the environment (sea intrusion problem, pollution of aquifers with fertilizers, herbicides, pesticides). these conditions, the need to reduce water consumption and use it more efficiently is imperative, aiming at sustainable water management. Today there is technology available that allows the use of satellite images and the application of an energy balance at crop and ground level to estimate actual evapotranspiration. This method, to give values, close to reality, must be calibrated using ground data. For this reason, cotton, and maize fields in Thessaly (Central Greece) were systematically monitored for soil moisture and final yield. These water consuming plants are widely cultivated in the Thessalian plain even though the area has a negative water balance. The data collected from the monitoring together with the simulation with the AquaCrop model led to the estimation of the actual evapotranspiration. The model results are considered to correspond to real evapotranspiration since water balance application conditions were favourable (runoff and deep percolation had small or zero values). As a resiult, using the estimation of ETA in the plot we were led to improve the satellite estimation of evapotranspiration.

Key words: Evapotranspiration, satellite images, monitoring, AquaCrop