An Estimation of Evapotranspiration Using SEBAL Method and its Comparison with Penman-Montieth: A Case Study of Bilevar Plain, Western Iran

Evapotranspiration from irrigated land is a useful indicator to evaluate the amount of water use in irrigation. Conventional methods of computing evapotranspiration are based on climate data and can only provide a point estimation. While better regional estimation of evapotranspiration can be obtained from satellite remote sensing and individual pixel to an entire image. One of the most popular remote sensing algorithms in the retrieval of ETa is Sebal. Sebal can calculate surface energy balance for each pixel of a satellite image at each moment. In this study, surface albedo, surface temperature and vegetation status index were calculated by using Sebal algorithm, multi-spectral satellite data and meteorological information such as degree of temperature, hours of sunshine, wind, saturated vapor pressure, soil humidity, etc. In this study, the evapotranspiration of Bilevar plain (located in western Iran) was determined and the evapotranspiration maps were prepared. Moreover, the actual evapotranspiration was computed for wheat using Penman-Montieth method and was compared to Sebal method. The results showed that there was a high correlation (0.83) between the abovementioned methods and that Sebal has a great ability to calculate evapotranspiration.