Explicit expressions for the vector fields of specific discharge and scalar fields of stream functions and piezometric heads in a Darcian steady-state essentially two-dimensional (2-D) flow through a three-component composite representing a vertical or horizontal well with a gravel pack and annular skin are obtained and analysed. The refraction conditions along two concentric circles, which represent interfaces between three porous media of contrasting hydraulic conductivities, are exactly satisfied. Flow nets, isotachs, the locus of the stagnation point bounding the capture zone of the well, and functionals quantifying area-averaged hydraulic characteristics are found. The flow topology and drawdowns near the well illustrate that at small pumping rates a common concept of a purely radial 1-D flow can be superficially plausible but misleading.

The misunderstanding of hydrogeological processes together with the oversimplification of aquifer conceptual models result in numerous inaccuracies in the management of groundwater resources. In Central Chile (32–36°S), hydrogeological studies have exclusively focused to alluvial aquifers in valleys (~15% of total area) and mountain-front zones remain considered as no-flux boundary conditions. By a topological approach and an analysis of fractures, the hydrogeological potential of the Western Andean Front along the N–S-oriented Pocuro Fault Zone (PFZ) in the Aconcagua Basin were determined. Perennial springs (23) show evidence of groundwater flows into the fractured Principal Cordillera. Topology allows for quantification of the density of connected fractures within the fault zone and its relationship with groundwater circulation. The study results highlight two areas where the density of fractures and connected nodes (Nc) is high (>2.4 km/km², 2.5 Nc/km²). Both areas are topologically related to the main springs of the PFZ: Termas de Jahuel (discharge ~14.0 m³/h at 22 °C) and Termas El Corazón (discharge ~7.2 m³/h at 20 °C). Outcrop-scale mapping reveals that groundwater outflows from NW–SE fractures, which is consistent with the preferential orientation of the fracture network (N30–60 W) within the PFZ. The results indicate that oblique basement faults are discrete high-permeability structures conducting groundwater across the Western Andean Front from the Principal Cordillera up to adjacent alluvial aquifers (focused recharge). Therefore, the simplistic hydrogeological view of the Western Andean Front (i.e. impervious limit) is partially erroneous.