Multi‐Variable SWAT Model Calibration Using Satellite‐Based Evapotranspiration Data and Streamflow

Abstract

In this study, monthly streamflow and satellite‐based actual evapotranspiration data (AET) were used to evaluate the Soil and Water Assessment Tool (SWAT) model for the calibration of an experimental sub‐basin with mixed land‐use characteristics in Athens, Greece. Three calibration scenarios were performed using streamflow (i.e., single variable), AET (i.e., single variable), and streamflow–AET data together (i.e., multi‐variable) to provide insights into how different calibration scenarios affect the hydrological processes of a catchment with complex land use characteristics. The actual evapotranspiration data were obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS). The calibration was achieved with the use of the SUFI‐2 algorithm in the SWAT‐CUP program. The results suggested that the single variable calibrations showed moderately better performance than the multi‐variable calibration. However, the multi‐variable calibration scenario displayed acceptable outcomes for both streamflow and actual evapotranspiration and indicated reasonably good streamflow estimations (NSE = 0.70; R2 = 0.86; PBIAS = 6.1%). The model under‐predicted AET in all calibration scenarios during the dry season compared to MODIS satellite‐based AET. Overall, this study demonstrated that satellite‐based AET data, together with streamflow data, can enhance model performance and be a good choice for watersheds lacking sufficient spatial data and observations.