Proposal for transitional framing and obtaining dilution flow in the Piauitinga River basin/SE

Abstract

This study had as objective to develop a proposal framing for the water bodies of the Piauitinga River, located in the state of Sergipe, located in the state of Sergipe, by determining effluent dilution flows using the QUAL-UFMG water quality model. To this end, calibration and adjustment were based on hydrological and water quality data from streamflow and monitoring stations, along with a survey of key basin users and their water demands. Based on CONAMA Resolution nº 357/2005 and considering the most restrictive predominant uses in the basin, a transitional classification was proposed. The results showed satisfactory model performance in the analyzed river segments. Simulations involving improvements to existing industrial effluent treatment systems and the installation of wastewater treatment plants (WWTPs) indicated a reduction of up to 38.2% in BOD concentrations. The transitional classification led to significant variations in dilution flows, with reductions reaching up to 98.97%. These findings demonstrate that the classification category strongly influences the volumes required to meet water quality standards, with dilution flows increasing as less restrictive classes are adopted. This study contributes to efficient watershed management, supporting decision-making for rational water use and ecosystem preservation.