Avaliação da evolução da qualidade da água superficial na bacia do Rio Pomba, MG, utilizando o índice IQA-CCME

Abstract

In recent decades, Brazil has been constantly suffering from water supply problems, both in terms of adequate quantity and quality, especially in large urban centers. In this sense, the monitoring of water resources becomes real and necessary, in order to understand the relationships involving water and the use and occupation of the soil in a basin, making it possible to propose improvement in the quality of water in a river or basin. This work uses a water quality index developed in Canada, the WQI-CCME, to assess the evolution of surface water quality in the Pomba River basin, in the state of Minas Gerais. The justification for this work is given by the relation of multiple uses of water in the basin, mainly the use for public supply. In this work, monitoring data from the Minas Gerais Water Management Institute - IGAM and the Minas Gerais State Sanitation Company - COPASA were used, between the years 1998 and 2019. The data used had three different treatments: Calculation of the WQI per point for each year of monitoring, Calculation of the WQI of the basin per year of monitoring, Calculation of the WQI per accumulated subsection of the basin. The WQI relationship with the flow data on the day of collection was also evaluated. The three models demonstrated that the Rio Novo sub-basin contributed to an improvement in water quality in the main channel and the Xopotó sub-basin was the main contributor to the worsening of water quality. The data also showed a relationship of worsening in the WQI when at peaks of large flows. It was also evidenced that the model of land use and occupation over time in the basin had a direct influence on water quality, especially in urban areas with the discharge of untreated domestic sewage into rivers. The water quality was kept in balance, no investigation format showed a trend of worsening or improvement in water quality over the time studied. However, the WQI presented itself as an effective tool with a simple methodology, its main advantage being the possibility of incorporating parameters into the index, however it presented high sensitivity in the calculation of the WQI with large oscillations in the incidence or absence of the coliform parameter.