O potencial hidrogeológico da folha de Frederico Westphalen, Região do Alto Uruguai - RS

Abstract

The Serra Geral Aquifer System (SASG) is of great importance due to the fact that most municipalities located in the Serra Geral Group use their underground water for public and private consumption. The demand, combined with the conquest and low cost tools available, nowadays has increasing the studies of the SASG. The study area is located at Frederico Westphalen’s Chart, northwest of Rio Grande do Sul and southwest of Santa Catarina, in the Alto Uruguai region, with a scale of 1:100,000. The demand for groundwater in this region is mainly in the watering of animals, industry, agriculture and tourism of waters with geothermal characteristics. Geologically, the studied quadrant is located in the Serra Geral Group, with a predominant presence of basalts and strong structuring of brittle tectonics. Thereby, the objective of this work is to determine the hydrogeological characteristics of Folha de Frederico Westphalen. The methodology used consist of create and adjuste the database of georeferenced wells in the region, using the specific capacity, complementation of linear structures (lineaments) made by means of satellite images and processing in Geographic Information System (GIS), generation of thematic maps and statistical analysis of the collected data. 922 photogeological lineaments were identified with four main trends, the N050-070W, N350-NS, N320-340W and E-W. From the three spatialized domains, it was observed that the lineament density has a strong correlation with the relief, and that the highest densities are present south of the Chart, represented by Domain 3 and 2. In general, the water productivity underground in the studied area is low. In the 223 wells, they present an average of 0.7 m³/h/m. From the boxplot of density classes in relation to specific capacity, it is observed that Domain 3 had the highest groundwater potential, followed by Domain 1. Domain 2 had lower productivity. However, it was verified that the relationships are not so clear, possibly due to the regional occurrence of hydrothermal and tectonic processes that filled these empty spaces by dikes, sills and mineralizations, increasing the heterogeneity of the studied area.