Diagnóstico socioambiental da bacia hidrográfica do Lajeado dos Pires em Itaara/RS

Abstract

The watersheds are used as basic units for the management of water resources and environmental planning, and one of the cause of environmental degradation of Brazilian watersheds is the deficiency of basic sanitation services. This is the case of the area of this study, whose lack of basic sanitation in the region caused changes in the water quality of the Lajeado dos Pires, becoming a problem for nearby residents. Moreover, it is known that the area has been going through a strong population densification caused by the increase in the number of buildings and changes in land use, which leads to soil sealing and a consequent increase in surface runoff. In this sense, the objective of the study was to analyze the influence of population density, especially regarding the use and occupation of the soil on the water quality of the Lajeado dos Pires watershed. For this purpose, physical, chemical and biological analyses of water quality were performed in 5 different points of the Lajeado dos Pires during the period from October 2020 to October 2021. The parameters were analyzed at the Engineering and Environment Laboratory of the Federal University of Santa Maria, using the methodology of the Standard Methods for the Examination of Water and Wastewater. After that, a socioeconomic questionnaire was applied to the population along the Lajeado river. Subsequently, the data of water quality parameters were related to the flow and also a correlative analysis of the results with the socioeconomic part of the area. The results showed that despite the fact that points 1, 2 and 3 are the highest, that is, farthest from the residences and industrial activities carried out in the basin under analysis, in certain periods, there were punctual discharges of effluents that altered the quality of the water at those points, probably caused by the existing agricultural activities in nearby regions. On the other hand, points 4 and 5, because they are located closer to the residences and the outfall, presented a greater change in water quality, especially with respect to total coliforms and E.coli, since these points receive a greater quantity and concentration of effluents from the activities carried out and by the use and occupation of the soil in the vicinity.