Qualidade e usos da água na bacia do Rio Cauamé no estado de Roraima

Abstract

Water is a strategic resource for human development, because in addition to being essential for living beings, it is strongly linked to social, economic and environmental development. Brazil holds a considerable portion of all fresh water in the world, with emphasis on the Amazon Basin, which includes the rivers that flow in the state of Roraima. Among the main basins of the state, that of the Rio Cauamé, a tributary of the right bank of the upper Rio Branco that drains the cities of Boa Vista and Alto Alegre in their urban and rural perimeters. The Cauamé basin underwent intense colonization during the state's formation period and currently suffers pressure in the urban space with the growth of the city of Boa Vista in its extreme southeast, and in the rural area with the implementation of agricultural projects and intense use of leisure places. . This scenario of growing demand for water and a lack of basic studies aimed at knowing the availability and quality of water, justifies the importance of this work. This research aimed to evaluate the quality and uses of surface waters in the Cauamé River basin, describing the predominant uses of the soil, classifying the water at the sampled points, determining the Water Quality Index and establishing relationships between the quality found and the land uses. Visits were carried out, survey of land use and occupation licenses and geoprocessing tools were applied to define the predominant land uses in the basin and the sampling points. Subsequently, six campaigns were carried out to collect water and measure parameters in the field (pH, temperature, total dissolved solids and turbidity). In the laboratory, the density of coliforms, biochemical demand for oxygen, phosphorus and total nitrogen were determined. The results made it possible to classify and classify water quality according to CONAMA Resolution No. 357/2005 and IQA, as well as the correlations with land use. Five of the 12 sampled points had class 4 and all the others had pH values that did not meet any class. The IQA showed that 75% of the sampled points are of regular quality and the others are of good quality. The sampling point that showed the best water quality has on its banks a dense riparian forest still preserved, possibly due to the importance of vegetation in containing the leaching and silting process. These results demonstrate the obstacles in framing the Rio Cauamé and the need for action by the competent bodies in order to mitigate the problems already encountered, including adapting and complementing the tools and parameters to monitor water quality, observing regional peculiarities.