WELLMO DOS SANTOS ALVES
Abstract:
Ribeirão das Abóboras is the main water body that supplies the Rio Verde (GO) population and is one of the main tributaries of the São Tomás River; This is the main source of water supply in Santa Helena de Goiás (GO) city. These municipalities are located in the Goiás Southwest microregion, with agribusiness-based economy, and the municipality of Rio Verde is the main economy of this microregion. The aim of this study was to evaluate the physical characteristics and water quality of the Ribeirão das Abóboras watershed in Rio Verde (GO). The physical characteristics evaluated using geotechnologies were morphometry, land use and vegetation cover from 1985 to 2015 and environmental fragility. The water quality variables evaluated were temperature (T), hydrogen potential (pH), dissolved oxygen (OD), electrical conductivity (EC), total dissolved solids (STD), suspended solids concentration (CSS), apparent color (CA), true color (CV), turbidity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate and total phosphorus (FT), the averages being compared to the limits for freshwater class 2 established by CONAMA Resolution 357/05. The study of trophic state was also performed with application of Trophic State Index (EIT) for TF. It was found through this study that: the area of this basin is characterized as more elongated, that is, it's less prone to large floods, compared to a circular basin; Ribeirão presents watercourse characteristics with predominance of soft undulating relief, facilitating agricultural practices; the basin is characterized as medium drainage density, inferring that the geological substrate and the pedological material are medium porous; land use and vegetation cover, diversified since 2005 and in a disorderly manner, without respecting the limits imposed by current environmental laws, caused significant environmental damage, including water pollution, such as BOD and TF variables in disagreement with CONAMA Resolution 357/05 and high trophic state indices, which ranged from mesotrophic to hypereutrophic. Such impacts may cause damage to the multipurpose water supply. Thus, it's necessary to plan land use and vegetation cover, reconciling economic interests with environmental preservation and especially the improvement of the quality of life of the population of Rio Verde and Santa Helena de Goiás.
