Estimation of Regional Evapotranspiration Using LANDSAT TM Images and SEBAL Algorithm

Estimation of evapotranspiration (ET) is essential for agricultural water resources management. Usually it is estimated indirectly based on (daily) weather data at the weather stations because of difficulties in its direct measurement. Considering the spatial variations of the weather parameters and subsequently of ET، application of the methods which can consider these variations are interested. Developed algorithms to estimate ET based on satellite images are among those interested methods. Surface Energy Balance Algorithm for Land (SEBAL); a remote sensing-based technique for estimation of evapotranspiration has been used in some regions in the world. The aims of the current study were 1) to test the accuracy of estimated ET based on SEBAL algorithm using LANDSAT5 TM images and 2) estimation of regional evapotranspiration over a plain. The study area was Mahidasht plain in Kermanshah، Iran. For this purpose، the ET of maize and regional ET was estimated based on four images of LANDSAT during the growing season of maize in the year 2010. Maximum difference between maize simulated ET and measured data was less than 10%.