Modelagem hidrológica e estimativa de cargas poluidoras em uma bacia hidrográfica rural

Abstract

The state of Ceará has a high number of reservoirs, in which the water stored in these places is extremely important for the population, making it necessary to monitor these environments qualitatively, and the analysis of pollutants released into them is essential. In this context, this study aimed to analyze the phosphorus polluting loads in a rural watershed, located in the semiarid region of Ceará, considering the hydrological variability of the region. Thus, the hydrological model SMAP was used together with a transient complete – mix water quality model to analyze the concentrations of total phosphorus. The study was carried out in the watershed of the Quixeramobim reservoir, located in the municipality of Quixeramobim in the state of Ceará, between 1997 and 2017. The calibration and validation processes performed in the SMAP presented a moderate performance of the model in relation to the objective functions used reaching 0.28 for the NASH coefficient and 0.61 for the correlation. The water quality model had an average maximum monthly load of 19.36 ton/year in March. For the average phosphorus concentrations, rates ranging between 0.040 g/m3 and 0.203 g/m3 were reached in which there was a higher concentration in the dry period. Such values, when compared to the data established by CONAMA resolution no 357/2005, are above the limit of 0.03 mg/l. The proposed methodology can contribute to the qualitative management of water resources.