Olive Evapotranspiration of a Drip-Irrigated Orchard Using the Clumped Model.

A study was performed in order to evaluate the for direct estimation of actual evapotranspiration (ET_a) and latent heat flux (LE) over a drip-irrigated olive orchard under semi-arid conditions. The orchard, with an average fractional cover of 30%, is located in the Pencahue Valley, Region del Maule, Chile. The performance of the Clumped (three-source) model was evaluated using an eddy covariance system during the 2010/11 growing seasons. Results indicate that the Clumped model was able to predict ET_a with a root mean square error (RMSE), mean bias error (MBE) and model efficiency (EF) of 0.44 mm day^-1, -0.31 mm day^-1 and 74 %, respectively. Also, the Clumped model simulated the daytime variation of LE with a RMSE of 40 W m^-2, MBE of -15 W m^-2 and EF of 80%.  The results obtained in this study indicate that the Clumped model could be used to directly estimate olive water requirements for a drip-irrigated orchard.  However, application of the Clumped model requires a good characterization of the orchard architecture.