A comparative study was carried out to evaluate the performance of the advection-aridity (AA) method and the Katerji and Perrier (KP) method to derive time series of actual evapotranspiration (ET). The AA method was formulated as a linear equation which relates actual ET to meteorological data. Meanwhile, the KP method is in a form of a linear equation which relates canopy resistance to meteorological data. Both the AA method and KP method need local calibration. Field work was conducted for the crop of maize and canola grown in the Coleambally Irrigation Area located in southeastern Australia. Results show that with locally calibrated parameters used in each method the AA method performed better than the KP method both for maize and canola crop. Future work will focus on use of the AA method to derive seasonal ET from satellite-based daily ET maps. The findings and methods in this study seem to be useful in deriving ET time series under other climate conditions.