Avaliação do Sistema Aquífero Serra Geral com um modelo de dupla porosidade baseado na análise de testes de bombeamento

The Serra Geral Aquifer System (SGAS) is composed of fractured aquifers associated with the structures existing in volcanic rocks, being a heterogeneous and anisotropic system. For this reason, the methods of Cooper & Jacob and Theis are not usually effective in translating as discontinuities in the medium and can lead to uncertain assessments. The use of other methods, such as those of Warren & Root and Moench relative to double porosity aquifers, may represent an alternative for the evaluation of this type of aquifer. Within this context, the objective of the study was to determine the efficiency of the use of double porosity models in the evaluation of fractured aquifers, comparing with the classic models, through the analysis of the adjustments of theoretical data to the data of drawdown obtained in the field. The available data come from pumping tests with observation wells carried out in a small hydrographic basin in the city of Caxias do Sul - RS, in which there is the occurrence of SGAS. Adjustments using double porosity methods revealed that they present good suitability in adjusting the drawdown curves and can be used to analyze hydrodynamic parameters of fractured aquifers, such as the SGAS. The Moench method stands out, the errors were 90% lower than the previous ones by the classic methods, showing that the latter are less effective in evaluating the hydrodynamic behavior of water in heterogeneous and anisotropic media.