Performance of SSEBop model for estimating wheat actual evapotranspiration in the Brazilian Savannah region

Abstract

ABSTRACTIn a scenario where supplying the increasing demand for food depends highly on irrigation, understanding the temporal and spatial variation of actual evapotranspiration (ETa) is essential for water resources management. In the last decades, several models for mapping and monitoring ETa using remote sensing data were developed and studied. In this work, the Simplified Surface Energy Balance for Operational Application (SSEBop) model was applied to estimate actual evapotranspiration of irrigated wheat in the Cerrado (Brazilian Savannahs) region, using ETM+/Landsat 7 and OLI-TIRS/Landsat 8 images. The results were compared with evapotranspiration calculated by the Bowen ratio method. Considering the data referring to satellites overpasses days, SSEBop overestimated ETa by an average of 13.6%, with a coefficient of determination (R2) equal to 0.82 and root mean square error (RMSE) equal to 0.89 mm d−1. Considering the daily data for the entire period, including the extrapolation for the days between the satellites overpasses, SSEBop overestimated ETa by an average of 5.5%, with R2 equal to 0.66 and RMSE equal to 0.95 mm d−1. The results obtained demonstrated a reliable performance of the SSEBop for estimating actual evapotranspiration of irrigated wheat in the Cerrado, which can contribute to improve the irrigation efficiency and reduce water use conflicts. Considering the simplicity of the modeling concept and operational implementation, it can also be beneficial for water agencies on water resources planning, management and regulation in the region.