Estimation of Actual Evapotranspiration using Surface Energy Balance Algorithms for Land Model: a Case Study in San Joaquin Valley, California

Almond is an important cash crop in semi-arid southern San Joaquin Valley, California. Estimating almond water use is an important research objective in the arid area of Paramount farm. A Surface Energy Balance Algorithm for Land (SEBAL) model spatially estimates actual evapotranspiration (ETa) in the southern San Joaquin Valley in California from available MASTER airborne data. The objectives of the study are: (1) to study the spatial distribution property of canopy surface temperature (Tc), Normalized Difference Vegetation Index (NDVI), and ETa over the San Joaquin Valley, (2) estimate ETa of almond class on pixel-by-pixel basis in the Central Valley, California, and (3) to compare ETa obtained from SEBAL model with Penman- Monteith method. The results show that the regression between ETa, and Tc show negative (-) correlation. The correlation coefficient of ETa from remote sensing with Penman Monteith was 0.85 with bias of 0.77 mm and mean percentage difference is 0.10%. These results indicate that a combination of MASTER data with surface meteorological data could provide an efficient tool for the estimation of regional actual ET used for water resources, irrigation scheduling and management