Evaluation of Spatial Evapotranspiration Estimation by the SEBS Model in a Dry Mountainous Region, Southern Iran

The conventional methods for actual evapotranspiration (ETa) estimating is not sufficiently accurate due to the point based nature of meteorological data and the difficulties related to the plant coefficient (Kc) estimation. The true rate of ET from a basin is an important factor of hydrological cycle and in the water balance equation and accounts for a huge part of out-flow of a basin or any other scale. In this study, the ET values were calculated in the region of Kelestan located in the northwest of Shiraz. The SEBS evapotranspiration model was applied and evaluated by using the Landsat 8 satellite images (nine images) and the meteorological data collected at the Kelestan Station for the period 2015–2017. Results were compared to the FAO Penman-Monteith equation to verify the accuracy of this model in the region of Kelestan. The radiation sources required for the SEBS model were produced by the R.sun module in Grass-GIS. Other remote sensing data were calculated in the Ilwis software environment. The results of evapotranspiration obtained from the SEBS model in comparison with the mentioned equation showed a correlation coefficient of 0.999, which is statistically significant. Variations of the ETa for different landuses were within a reasonable range. The production of reliable data from evapotranspiration is one of the prominent advantages of using this model for application in hydrologic research of the basin.