Estimating evapotranspiration using remote sensing and the METRIC energy balance model: case study of Sidi Benour region (Morocco)

Morocco has become an increasingly frequent and severe drought episode due to climate change in recent decades. This has significantly reduced freshwater, especially in areas characterized by significant agricultural potential, such as the Sidi Bennour region. Consequently, rational and sustainable management of existing water resources has become essential. The main objective of this study was to estimate evapotranspiration by applying the METRIC energy balance model (mapping evapotranspiration at high resolution with internalized calibration). Thus, this application, based on the combined use of auxiliary climate data and high-resolution optical satellite data (Landsat 8 OLI), allowed the evaluation and spatial distribution, at the scale of the Sidi Bennour region, of the different variables (net radiation, surface temperature, sensible heat flux, latent heat flux) controlling the evapotranspiration. The analysis of the various images derived, especially that of evapotranspiration, shows that these variables change depending on the presence and condensation of cultures. The results of this study are satisfactory and allow us to conclude that the METRIC model is a promising and operational approach for the evaluation, spatialization, and monitoring of evapotranspiration by remote sensing. The interest of this study lies in the importance of the precise knowledge of the evapotranspiration through the derived image, which will constitute an essential document for the persons in charge of the irrigation and the farmers in order to evaluate the need for the water of the cultures and to an integrated management of the water resources that become increasingly rare in the study area.