Comparison of Evapotranspiration Estimates from Remote Sensing (SEBAL), Water Balance, and Crop Coefficient Approaches

Three independent approaches were applied to estimate annual evapotranspiration (ET) for the Imperial Irrigation District of Southern California for the 1998 water year (October 1997 to September 1998). These approaches included remote sensing (Surface Energy Balance Algorithm for Land, SEBAL®), a district-wide water balance with ET as the closure term, and a dual crop coefficient approach based on the procedures of FAO Irrigation and Drainage Paper No. 56 with refinements to account for field-specific irrigation frequency. Differences between annual ET from each independent ET estimation approach are evaluated relative to estimated confidence intervals.