Application of SEBAL method to estimate crop evapotranspiration in arid regions of Chile

Evapotranspiration is a biophysical variable difficult and expensive to estimate by conventional methods, but it’s essential to determine the net irrigation water requirements, especially in arid regions. For this study, a pilot crop area in the extreme arid region of Atacama Chile was selected to estimate evapotranspiration by the Surface Energy Balance Algorithm for Land Method (SEBAL), developed by Bastiaanssen et al., in 1998. SEBAL was applied to 12 Landsat 7 ETM+ images recorded in 2000. The spectral radiances plus routine weather data and topographic information (ASTER GDEM) were used to solve the energy balance at the earth’s surface. A spatially distributed daily evapotranspiration data and also its evolution during the year were obtained for the pilot crop area. The results are reasonable similar to the available validation data estimated by Penman-Monteith in previous studies.