ABSTRACT
The main goal of this study was to seasonally model the water quality of Sinos River, in Rio Grande do Sul state, Brazil, using as support the QUAL-UFMG mathematical model. Nine monitoring sections were performed, between the counties of Caraá and Canoas, in a 211-km-long stretch. The water quality variables were analyzed between 2011 and 2012, in order to comprehend the different seasonal variations. The model was calibrated using the water quality variables: biochemical oxygen demand (BOD); dissolved oxygen (DO); total phosphorus (Ptotal); and total nitrogen (Ntotal). The seasonal variations demonstrated to influence the different simulated calibration curves. Thus, the utilization of QUAL-UFMG mathematical model in Sinos River water quality evaluation was appropriate, since there was a similarity between the observed data and the simulated curve in the calibration process. For DO, the model presented good efficiency (Nash and Sutcliffe Coefficients - CNS>0.75), and for BOD, Ptotal and Ntotal variables (autumn/winter), the model was considered acceptable (0.36<CNS<0.75).
Keywords:
mathematical model; calibration; water resources; seasonal variation