Analysis of water inflows and their relationship with the productivity of tubular wells that capture water from the Serra Geral Aquifer System in the municipality of Passo Fundo (RS)

Abstract

The Serra Geral Aquifer System (SGAS) is characterized by fractured aquifers in which well productivity varies spatially, with wells commonly presenting different degrees of yield as well as multiple water inputs (W.I.). Therefore, this study was conducted in the area encompassed by the municipality of Passo Fundo, which is located in a region more favorable to the occurrence of fractured aquifers. For this study, geological and construction data (well depth, lithologies, water inputs and weathering mantle thickness), as well as hydrogeological data (static level, stabilization flow rate and specific flow rate/specific capacity), were analysed. These data were obtained from well construction logs and drilling and pumping test reports. The results indicate the occurrence of wells with moderate to high productivity, with 17% presenting stabilization f low rates greater than 25 m³/h and 32% showing specific flow rate/specific capacities higher than 1 m³/h/m. Water inputs are predominantly concentrated at depths between 25 and 100 m, suggesting a slight increase in flow rate with increasing depth of W.I. occurrence. The identified W.I. are located mainly in the range of 25 to 100 m depth, indicating a tendency for flow rate to increase with the depth of occurrence of the W.I. Furthermore, it was possible to identify that the range of 550 to 620 m altitude has a greater quantify of W.I associated with wells of higher productivity (> 20 m³/h). No strong correlation was observed between the thickness of the weathering mantle and the stabilization flow rate or specific flow rate/specific capacity parameters. However, it was possible to identify regions where wells with higher productivity are influenced by lineaments and W.I.