Actual evapotranspiration estimation using METRIC model and Landsat satellite images over an irrigated field in the Eastern Mediterranean Region of Turkey

Actual evapotranspiration ( ETa ) estimates at regional and river basin scales can assist water authorities with water allocation decisions in agriculture and the ecosystem. Remote sensing is cutting-edge technology as well as a robust tool for generating spatiotemporal variation of energy balance components over large areas. The objectives of this study were to: (a) estimate and generate fully distributed ETa maps by the “Mapping Evapo Transpiration at high Resolution with Internalized Calibration” (METRIC) in the Akarsu Irrigation Area ( A = 9495 ha) in the Eastern Mediterranean Region of Turkey, (b) compare ETa estimations with crop evapotranspiration (ETc) series acquired by FAO-56 methodology, i.e., “two-step approach” and (c) investigate the correlation between Kc obtained by the METRIC model and Normalized Difference Vegetation Index (NDVI) for some specific crop types. Landsat satellite imagery data with 30 m by 30 m spatial resolution and meteorological data of two ground stations (L8 and Adana) were used to estimate daily and monthly ETa by the METRIC model in the winter and summer seasons of 2020. Results showed acceptable agreement between ETa and ETc estimations. ETa maps reflected the changes in parallel with crop type variations over the study area in the summer and winter seasons of 2020. A strong and moderate correlation was found between Kc acquired by METRIC (ETrF) and NDVI ( r = 0.91 for Peanut1 and r = 0.55 for Corn1) in the summer season. Research results led us to conclude that remote sensing technologies could be applied to quantify the spatiotemporal dynamics of surface energy balance variables for irrigation and non-irrigation seasons. Moreover, ETa estimation by the METRIC model could be used over large-scale irrigation schemes in realizing rational irrigation scheduling efficiently and managing agricultural water more effectively.