QUALIDADE DA ÁGUA DO CÓRREGO DO SAPO NA ZONA URBANA DE RIO VERDE - GO

Abstract

In the state of Goiás, the city of Rio Verde has experienced in recent decades a strong increase in population and boosting of the economy, largely due to activities related to agribusiness. Such population expansion has led to the expansion of the urban area, and to an increase in human activities that occur in the region, contributing to greater releases of wastewater into water bodies. In urban areas, water courses fulfill important functions, acting in rainwater drainage, local landscape harmony, recreation, activities associated with food production, dilution and removal of effluents, human and animal supply. Thus, this research has as its focus the qualitative aspect of water in the urban stretch of the Sapo stream watershed, municipality of Rio Verde (GO), evaluating the characteristics of land use and occupation as well as the behavior of self-purification of organic matter exhibited by the water body. The water quality data were obtained through the monitoring of the Sapo stream (urban section), during a period of nine months, while the land use and occupation maps were obtained through geoprocessing techniques. To determine the self-cleaning capacity of organic matter, the QUAL-UFMG mathematical model was used. The results obtained allowed to identify that the two tributaries of the Sapo stream with the worst behavior in terms of water quality were the Buriti and São Tomás de Baixo streams. In both water bodies, points of point pollution were identified, as well as the existence of diffuse pollution, associated with the use and occupation of the land. From the analysis of the results, it was noticed that the watershed of the Barrinha stream had the best water quality during the study. Dividing the flows measured in the research into four scenarios for the study of self-purification, it was noticed that the bands with lower flows were those that indicated the greatest damage to water quality. The Sapo stream presented a satisfactory capacity for self-purification of organic matter up to the point of mixing with the Buriti stream, however, downstream from the confluence was not able to re-establish its equilibrium conditions within the study section. Furthermore, it was found that in some stretches of the Sapo stream water is being used in non-compliance with those established by CONAMA Resolution No. 357/2005.