Monitoramento ambiental dos córregos urbanos no município de Palmas - TO

Abstract

Urbanization is an event of transformation from rural areas to urban areas, usually linked to the development of civilization and subsequent population migration. In the implementation of urban centers, the parceling of the native soil by several units of fragmented land begins, in these processes the natural areas are occupied by impermeable surfaces. The Municipality of Palmas - TO presents environmental problems related to the use and irregular occupation, as a consequence, this dynamic exerts intense anthropic pressure in the urban watersheds of the municipality. In this context, we sought to disseminate knowledge about the control of anthropic activities arising from the implementation of urban centers. This research analyzed the qualitative and quantitative patterns of water bodies and the dynamics of the evolution of land use and occupation in urban watersheds from 1988 to 2020. The study area is composed of 8 urban watersheds in the municipality of Palmas – TO, being Cachimbo stream, Sussuapara, Brejo Comprido, Prata, Machado, Santa Barbara, Taquari and Cipó. Water quality analyzes were carried out at 24 specific points distributed by streams, in two periods of the year 2021 (dry and rainy). The following parameters were analyzed: temperature, electrical conductivity, turbidity, total dissolved solids, pH, biochemical oxygen demand, dissolved oxygen, ammonia, nitrite, nitrate, total phosphorus, Chlorophyll a, total coliforms and Escherichia coli, according to the conditions and quality standards established in CONAMA Resolution 357/05 for class 2 water bodies. The hydrological aspects were evaluated by measuring the flows in 8 points distributed by the streams, in the dry and rainy period of the year 2021. The dynamics of the evolution of the use and Land occupation was carried out by multitemporal analysis of microbasins and their APPs, in the years 1988, 1999, 2010 and 2020.The water quality results show that urban streams have concentrations of Escherichia coli and total coliforms above the limits allowed for class 2 water bodies, as established by CONAMA Resolution 357/05, in the dry period most of the streams have proportions of dissolved oxygen below Resolution standards. The evaluation of the hydrological aspects demonstrates that in the dry season the streams have a reduction in hydrographic flow. The results of the spatio-temporal evaluation of land use and occupation show that urban advances caused changes in the studied watersheds. After the implantation of the municipality, the areas of forest formations continuously reduced over the years, as the urban area expanded. The procedures employed in the study denote that urban expansion overlapped areas with a degree of soil protection, this scenario may compromise the natural ecological maintenance of watersheds, limiting the provision of their ecosystem services.