Abstract
The aim of this study is to investigate the potential of the Shuttleworth-Wallace (SW) model to provide accurate estimates of actual evapotranspiration (ET) and its partitioning into plant transpiration (T) and soil evaporation ( E) of an irrigated olive (Olea europaea L.) orchard in the semi-arid region of Tensift-basin (central of Morocco). SW model is a two-source model driven by meteorological data and in-situ soil moisture, surface temperature and leaf area index in order to compute both soil and vegetation resistances. Two years (2003 and 2004) of continuous measurements of ET with the eddy covariance technique were used to test the performance of this model. Model simulations were compared to data obtained from eddy covariance ET measurements and scaled-up sap flow measurements of transpiration. Overall, despite the complexity of the study field (tall, sparse trees), the results showed that the model gives acceptable estimates of ET and T with an overestimation around wetting events (irrigation and rainfall). The root mean square error (RMSE) between simulated and measured ET (resp. T) are 0.74 (0.13) and 0.62 (0.26) mm day(-1) for 2003 and 2004, respectively.