Evaluation and comparison of estimation of evapotranspiration of wheat crop using Sabal algorithm and Penman-Montith method in Chah-e-Nimeh region of Sistan and Baluchestan

Estimation of plant water consumption or evapotranspiration is necessary for management and planning of water and agricultural resources, hydrological balance as well as approximate estimation of crop yield. There are various methods for determining evapotranspiration on a small scale using field measurements such as lysimeters, which are highly accurate but are not widely used due to their high cost and difficulty. For this reason, methods based on telemetry and the use of satellite imagery have received more attention from researchers. Therefore, due to the importance of the subject in this study, the evapotranspiration in the Chah region of Sistan and Baluchestan was estimated using satellite images and Sabal algorithm. In this research, Landsat 8 satellite images for 1396 and 1398 have been used and to compare the results obtained from the remote sensing method (Sabal), from the data of the synoptic meteorological station of Zahak city to estimate evapotranspiration by FAO-Penman-Montith method has been used. Using statistical indicators such as relative error and explanatory coefficient, the ability and performance of remote sensing and Sabal algorithm were investigated. Thus, the values of statistical indices in 1396 and 1398 for the coefficient of determination are 0.82 and 0.95, respectively, for the root mean square error (RMSE) with values of 2.15 and 1.27, respectively, as well as the mean error Absolute (MAE) values are 1.49 and 1.11, respectively, and finally the mean oblique error (MBE) is 0.27 and 0.09, respectively.The results indicate the acceptable accuracy of the Sabal algorithm in estimating actual evapotranspiration.