Modelagem numérica de fluxo no sistema aquífero cristalino, município de Itu (SP)

Fundação para o Desenvolvimento da Unesp (Fundunesp) ; The crystalline aquifer system occurs in the eastern portion of São Paulo state, with 61,312 km2 area. Due to the low productivity associated to this aquifer, it is still few used as a water resource, a scenario that has changing with the growing cities demand. Previous studies has associated higher productivity to the existence of expressive lineaments, a thick weathered zone, or the presence of few expressive fractures connected to water bodies. With the objective of understanding the groundwater governing dynamics in crystalline terrains, focusing on surface water contribution in deep tubular wells production, the present study developed a numerical flow model based on information gathered from field lithostructural survey, interpretation of pumping test diagnostic plot and stable isotopes analysis. The finite elements method was used to elaborate the model through FEFLOW algorithm. The structural survey shows predominance of two main fracture families, both vertical and high frequency; the vertical fracture analytical model was fitted to drawdown and derivative plots; the isotopic data suggest surface water contribution in deep tubular well production located next to water body. The conceptual model elaborated admits a set of hidraulically interconnected subvertical discontinuities, responsible for connecting the pumping well to the river. Based on the numerical simulation results, the maximum contribution of surface water in the well production after 1440 minutes of continuous pumping was estimated at 12.6%, while the aquifer would account for 87.3% of the volume extracted ; O sistema aquífero cristalino ocorre na porção leste do estado de São Paulo, com 61.312 km2 de área. Devido à baixa produtividade associada a este aquífero, ainda é pouco utilizado como recurso hídrico, cenário que tem se alterado frente à crescente demanda dos municípios. Estudos anteriores associam maiores produtividades à existência de lineamentos expressivos, manto de alteração ...