Modelagem matemática da autodepuração de um trecho do Rio Jacuí – RS

Abstract

Water pollution from domestic sewage, industrial effluents, pesticides and animal waste due to accelerated and concentrated population growth plus the indiscriminate use of natural resources is a worldwide concern. Water deterioration has serious consequences such as scarcity, public health problems, changes in aquatic fauna, and other environmental impacts. Thus, the characterization of land use and occupation and mathematical modeling can be fundamental tools to aid water resources management. In this context, this study aims to estimate the amount of domestic effluents generated in the Baixo Jacuí basin, to classify the use and occupation of the region's soil and to evaluate the self-purification process of a Jacuí river section using the QUAL-UFMG mathematical model. In the region of the lower Jacuí basin around 53.535.560 L / day of domestic effluent is generated, where only 56.36% of the municipalities in the basin have adequate sanitary sewage (septic tank or general network). The other 43.64% is discharged improperly and directly into a receiving body or rainwater drainage networks. In addition, the Jacuí River is exposed to various anthropic actions, where agriculture is dominant; 68.07% of the basin is intended for agricultural purposes, together with the presence of urban and industrial centers (0.62%), exposed soil areas (7.67%) and forest and water areas 22.07% and 1 , 58%, respectively. And according to the modeling, in general the water quality variables of the Jacuí river stretch were within the standard established according to CONAMA Resolution 357/05. However, in order to preserve the Jacuí River waters, there is clearly a need for investments and incentives in basic sanitation planning actions, especially in the implementation of Sewage Treatment Stations - ETE in the municipalities of the region. In addition, the Baixo Jacuí Basin has intensive agricultural activity, which needs the great attention of environmental agencies, such as inspection and protective measures to preserve the region's natural resources.