Estimation of the actual evapotranspiration in olive orchard using a two-layer model integrating climate and satellite data

Traditionally, irrigation labor considers the value of reference evapotranspiration () and crop coefficient to estimate actual evapotranspiration (). This methodology presents significant errors in the obtention of . To avoid using empirical values of Kc, some authors suggest using two layer models to estimate over sparse canopies such as olive orchards. However, the model does not consider the effect of spatial variability corresponding to the size of the canopy, leaf area index () and fractional coverage () on the quantification of . For this reason, a study was carried out to estimate using the Shuttleworth-Wallace () model over a drip irrigated olive orchard using as inputs climatic and satellite data. The experiment was performed over a 6.45 ha, processing 7 Landsat images acquired from 2009 to 2010. The information was used to calculate instantaneous net radiation () and instantaneous soil heat flux (), which estimated the instantaneous available energy (). The SW model performance was compared with the eddy-covariance () method. Results indicate that estimated through climatic and remote sensing information () shows an error of 10% with a RMSE and MAE values of 0.31 and 0.28 mm day-1 respectively. For estimated through climatic information () an error of 10% and a RMSE 24% higher than was observed, showing that the use of spatially distributed variables such as and could improve the performance of the proposed model