Uso da terrra e caracterização hidropedológica na região de vila Kramer, São Francisco de Assis - RS

Abstract

The knowledge about the physical-natural environment to be explored is extremely important for the correct development of human activities. The planning of land use and occupation minimizes the environmental impact, therefore, providing a balanced ecosystem in its different phases. The incorrect use of land can harm considerably the environment, which is many times irreversible. The aim of this work was to evaluate the use of land in different times, to study the natural vulnerability of aquifer systems and to evaluate the physical-chemical parameters of groundwater in the region of Vila Kramer, in the city of São Francisco de Assis, Rio Grande do Sul, State, Southern Brazil. A soil study was made, identifying and characterizing the different soil classes which occur in the area, using geoprocessing techniques. Different soil maps were made, such as: geological, hypsometrical, gradient index, land use in 1989, 1999 and 2009, Permanent Preservation Areas (PPAs), agricultural sustainability, and adaptation of the soil use. There was also an identification of the areas with land use conflict. The tool used to study the natural vulnerability of aquifers (confined/not confined) was the DRASTIC and GOD methodology. In order to characterize the groundwater, an analysis of physical and chemical parameters was made using the water collected from the wells. The results showed that the natural forest cover presented a significant decrease between 1989 and 2009, which corresponds for 26.32% of the area. In the areas without forest there was not much difference between 1989 and 1999 considering this class of use. In 2009 there was an increase of 10.16% compared to the past decade. This increase is related mainly to the decrease in the areas used with crops. As a result we can highlight, in relation to the natural vulnerability of the aquifer area, that, the DRASTIC methodology ranged between vulnerable, high vulnerable, and extremely vulnerable area, while in the GOD methodology it ranged between negligible, low moderate, high and extreme. The DRASTIC and GOD methodologies provided approaches to identification of the vulnerability of the areas and the natural conditions of the aquifers, as well. From this point, it is possible to have the use of GIS, through the delineation of theme maps, which can be used to sustainably manage the hydric groundwaters resources.