Qualidade da água e sua relação com o uso da terra em duas pequenas bacias hidrográficas

Abstract

The creation of rural settlements in areas of agrarian reform has been allowing greater social inclusion for families who were previously deprived of land ownership and subsequent income source. However, unorganized splitting or inadequate location of infrastructure in places historically worked can hamper economic and social activities of a settlement project, apart from causing environmental damage. This study had the following aims: (a) temporal diagnosis of land use and occupation of the Alvorada settlement in two distinct periods, before its creation and after 12 years of occupation, (b) to map the land-use conflicts in areas of permanent preservation in two small watersheds located in the settlement, (c) to analyze the existing relationship between land use, riparian zones and water quality of streams in the two small watersheds, and (d) to assess the potential of water used for human consumption in rural properties as a risk factor to consumers health. The Alvorada settlement is situated in southern part of the city of Júlio de Castilhos, located in the central region of Rio Grande do Sul. To better discuss the results, this dissertation is organized in three studies. In the first, the temporal diagnosis of use and occupation of the land in the Alvorada settlement by means of cartographic products in two distinct periods, before its creation and after 12 years of settlement, was made, and the conflicts of land use in area of preservation in two small watersheds were identified. The second study dealt with the relations between water quality, land use and riparian zone in two small watersheds. In the third study monitoring the water quality of sources used for drinking-related to land use and conditions surrounding the protection of the cavity drilled in two small watersheds was performed. Analysis of thematic maps allowed better visualization of changes in the geographic area of the settlement. The main changes relate to population pressure and the replacement of areas formerly used for pasture or native grassland by annual crops and extensive dairy farming. Both the small watersheds showed land use conflicts in the areas of permanent preservation totaling 86.39% of the area in a small watershed and 100% in two small watershed. The waters of the streams showed a low concentration of chemical elements reflecting the low use of agricultural factors by the farmers. The organic load showed a small contamination, this is due to physical degradation of the landscape. There was no improvement in water quality parameters in the small watershed with the highest percentage of riparian forests which was attributed to the loss of their original characteristics by grazing animals and the felling of trees inside the forest. The water used for drinking water in the two small basins showed physiochemical and microbiological parameters outside limits for drinking water as established by the Ministry of Health; thus representing a high risk and health damage to humans who drink it.