Hydrological modeling for the piracicaba river basin to support water management and ecosystem services

Abstract The application of hydrological modeling is very important to support decision makers, providing technical basis for better management of water resources, correct use of soil and introduction of sectorial policies and programs, identifying potential areas for their implementation. In this study, the SWAT model was calibrated and validated and its performance was evaluated for the simulation of flow, total solids, total nitrogen and total phosphorus in the Piracicaba River basin. The performance of the model was evaluated based on the coefficient of determination, the Nash-Sutcliffe efficiency parameter (NS) and its logarithmic version, as well as on the percentage bias analysis (PBIAS). For simulation of the monthly flow, the NS values varied from 0.72 to 0.89 for the calibration period and from 0.50 to 0.75 for the validation period. Total solids showed NS greater than 0.48 and PBIAS less than 20.90%. For the nitrogen and total phosphorus data, the NS ranged from −1.53 to 0.78, with PBIAS below 42.62%. Based on the statistical parameters, after calibrating the SWAT model, it was able to properly reproduce the studied variables, providing a good fit between observed and simulated data, enabling the use of this tool to manage water resources, as well as supporting Payments for Ecosystem Services.