The Surface Energy Balance Algorithm for Land (SEBAL®) was applied to estimate remotely sensed evapotranspiration (ET) in the Sacramento Valley (California) for the 2001 crop growing season. The ET estimated by SEBAL was compared to ground-based Surface Renewal ET estimates for a rice field near Nicolaus at daily, monthly and seasonal time scales. For June through September (the period of coincident ET estimates), the SEBAL ET estimate of 33.0 inches was 5 percent more than the Surface Renewal estimate of 31.4 inches. The April 1 through September 30 rice ET estimated by SEBAL was 42.9 inches for this field.

Additionally, district-wide rice crop coefficients were developed for Glenn-Colusa Irrigation District (GCID). GCID is the largest irrigation district in the Sacramento Valley, serving 138,800 irrigated acres. The primary crop grown in GCID is rice. The SEBAL ET results for rice fields in GCID were used to compute average crop coefficient values for each image date and for the months of April through September for the 2001 growing season. The crop coefficients developed from remotely sensed ET were compared to published crop coefficients for rice ET. For the 2,060 rice fields identified for the crop coefficient analysis, the average full April 1 through September 30 rice ET estimate by SEBAL was 39.0 inches.