Spatializing and validating daily evapotranspiration over a Mediterranean vineyard watershed

Daily Evapo-Transpiration (ET) was spatialized over a Mediterranean vineyard watershed by using ASTER data along with the S-SEBI model. Validation over seven contrasted sites was performed using an original procedure that allowed easier multi-site monitoring without being much expensive. It made use of neutron probe data for calibrating the HYDRUS-1D model that simulates vadoze zone water transfers. The calibration of the HYDRUS-1D was satisfactory, with a 6% relative error on water storage. Validation over two contrasted sites of HYDRUS1D against eddy covariance data showed the model simulated daily ET with a 0.6 mm.d−1 accuracy. Finally, daily ET derived from ASTER / S-SEBI were validated against HYDRUS-1D simulations. The obtained accuracy was about 0.8 mm.d−1, regularly quoted as a requirement for further applications.