A comparison of SWAT model-predicted potential evapotranspiration using real and modeled meteorological data

Adequate characterization of potential evapotranspiration (PET) plays a critical role in hydrologic budgets, rainfall-runoff models, infiltration calculations, and drought prediction models (to name a few applications). The availability of reliable and continuous meteorological data remains a challenge; therefore, it is common to use modeled (simulated) meteorological data. This research used the Soil and Water Assessment Tool (SWAT) to estimate PET using different meteorological input data (simulated vs. real data) and the three commonly used PET calculation methods (viz. Penman-Monteith, Hargreaves, and Priestley-Taylor). The overall goal of this research was to determine the accuracy of prediction using simulated and real meteorological data when used with three PET calculation methods. Initial input layers to SWAT were: digital elevation models, soils, and land use. Real meteorological data were obtained from three local meteorological stations, whereas simulated meteorological data were generated by SWAT using one nearby national meteorological site. The model-predicted PET results were validated using independent PET measurements from Florida Automated Weather Network sites. The results of the study indicate that the difference in predicted PET between simulated (modeled) and real meteorology for a given PET calculation method is not significant; however, it is significant across the methods of PET calculation.