Aplicação do modelo SWAT na estimativa da evapotranspiração na bacia hidrográfica do rio Piranhas-Açu no estado do Rio Grande do Norte

Abstract

The modeling has stood out for allowing the prediction of the functioning of several natural systems including watersheds, emerging as an alternative to obtain ET evapotranspiration estimates. The present work aimed to evaluate the performance of the SWAT (Soil and Water Assessment Tool) hydrological model, in the simulation of the ET for the Piranhas-Açu river basin (BHRPA), in the Rio Grande do Norte stretch, in the absence of calibration. The basin area information used in the simulation is for topography, using the Digital Elevation Model (MDE) provided by EMBRAPA, Climate Forecast System Reanalysis (CFSR) weather data available from Global Weather Data for SWAT, soil classes and characteristics of use and occupation obtained from the Soil and Land Cover and Land Use Maps of Brazil acquired from the Brazilian Institute of Geography and Statistics-IBGE. To comparation the results of the hydrological simulation, the ET through the water balance (BH) was calculated for locations within the study area. The Nash and Sutcliffe (NSE) coefficient values ranged from satisfactory (0.61) to very good (0.82), from the performance index (c) from good (0.67) to very good (0.81), for all locations a strong correlation index (r) was obtained. The ME and Pbias statistical indices show an underestimation of the simulated ET compared to the calculated one. It was found that the SWAT model used without calibration presented a good performance to simulate ET for BHRPA.