Investigating Actual Evapotranspiration in Different Land Uses in Mountainous Areas using Sebal Algorithm and a Combination of MODIS and Landsat8 Satellite Images

Evapotranspiration is one of the most effective components of a catchment water balance in arid and semiarid regions of the world. The purpose of this study was to compare the accuracy of the estimation of actual evapotranspiration of different land uses in the surface energy balance algorithm (Sebal) Special mountainous regions of the FAO Penman-Monteith compared with the values calculated by a combination of MODIS and Landsat 8 images at the same time in Malayer city. Sebal algorithm estimates the energy component of the surface net radiation flux, soil heat flux and sensible heat flux to calculate the evapotranspiration instantly and daily. In this study, the eight images of MODIS and Landsat select from 2005 to 2013 at the same time. Meteorological data used include maximum temperature, minimum temperature, relative humidity, sunshine and wind speed were extracted during this period from Malayer synoptic station. To investigate the relationship between the amount of actual evapotranspiration and land use were used by the Zonal Statistic method. The results showed that the estimated daily average of evapotranspiration has 0.43 percent difference between FAO Penman-Monteith method and Sebal, therefore accuracy of Sebal algorithm can be acceptable. The land use map was provided by object oriented approach with 88% accuracy and kappa coefficient. The minimum and maximum amount of ETR are irrigated farming and residential. The largest standard deviation of ETR is rangeland and the lowest SD is water bodies.