Browsing by Author "Villela, Daniela"

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    Assessing Structural Geological Controls on Groundwater Processes in Mountain Settings: Insights From Three‐Dimensional Numerical Modeling
    (2025) Marti, Etienne; Leray, Sarah; Roques, Clément; Yáñez Carrizo, Gonzalo Alejandro; Poblete, Fernando; Abhervé, Ronan; Tapia, Felipe; Villela, Daniela; Butikofer, Pol
    Mountains play a critical role in the hydrological cycle by transferring heavy precipitation to lowland aquifers. However, their complexity and remoteness limit our understanding of groundwater flow, particularly the influence of faults. To fill the gap, semi-idealized 3D numerical models calibrated using the mountain river network and the lowland piezometric gradient were developed. The impact of faults on groundwater flow was explored by varying their hydraulic conductivity, position, orientation, and length. The metrics evaluated were flow partitioning, seepage area, flow path lengths, and residence times. It was found that the hydraulic conductivity contrast between a fault and the pervasive rock controls recharge partitioning as much as the overall transmissivity of the pervasive rock. Regional conductive faults parallel to the orogen promote mountain-block recharge over surface flow, as significantly as thick systems do, and vice versa. Local-scale faults can exert as much influence as regional faults when crossing the catchment outlet, highlighting the importance of local heterogeneity in regional flow dynamics. Intercatchment flow is primarily governed by lithology and topography and is modulated by the fault position relative to major topographic features. Faults influence seepage areas within a multi-kilometer distance in characteristic patterns useful for segregating their effective role. By lowering the water table, conductive faults systematically reduce the seepage areas. Meanwhile, barriers decrease seepage areas downstream of their trace and increase them upstream, without affecting the extent of seepage. Finally, the distributions of flow path lengths and residence times are uncorrelated, highlighting the importance of numerical modeling for groundwater dating.
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    Unravelling geological controls on groundwater flow and surface water-groundwater interaction in mountain systems: A multi-disciplinary approach
    (ELSEVIER, 2023) Marti, Etienne Bernard Christian; Leray, Sarah Tiphaine Lucile; Villela, Daniela; Maringue Canales, José Ignacio; Yañez Morroni, Gonzalo José; Salazar, Esteban; Poblete, Fernando; Jiménez, Jose; Reyes, Gabriela; Poblete Farias, Guillermo Hernán; Huaman Sevilla, Zeidy Lisseth; Figueroa González, Ronny Javier; Araya Vargas, Jaime Andrés; Sanhueza, Jorge; Muñoz, Marjorie; Charrier, Reynaldo; Fernández, Gabriel
    Mountain water resources are considered to be the world's water towers. Still, despite their importance for downstream societies and ecosystems and their vulnerability to climate change, they remain poorly understood - It is the case in particular of mountain groundwater systems. Their complexity makes them difficult to conceptualize, while their remoteness makes them difficult to study, both observationally and instrumentally. Understanding mountain hydrogeological systems is mostly limited by the lack of characterization of the subsurface geologic framework and by the limited understanding of the role of geological structures on groundwater flow and on surface water-groundwater interaction. Removing methodological barriers is therefore a necessary step for improving the understanding of mountain hydrogeological systems. To tackle this problem, we develop a comprehensive multi-disciplinary approach to gain insights into the hydrogeological role of geological structures in ungauged mountain catchments. The methodology consists of several complementary methods: (1) geological mapping at multiple scales; (2) a geophysical study including on ground Electrical Resistivity Tomography (ERT) and, gravimetry transects, and a UAV-based magnetic survey; (3) hydraulic data, including a 9 km long transect of streamflow measurements in the recession period, the longterm Normalized Difference Vegetation Index (NDVI), and varied hydric markers (e.g., a thermal spring and a puddle). The methodology is tested in the Parque Nacional del Rio Clarillo, an ungauged catchment in the Andes Mountains (& AP;130 km2) that is illustrative of the complexity of mountain hydrosystems featuring fault zones, weathered zones, intrusive rocks, and volcano-sedimentary successions.An increase of approximately 50% in the streamflow is observed over a short distance of 1 km. Such a localized and significant increase in the baseflow is not related to any superficial supply and can only be explained by groundwater exfiltration. Based on the multiscale geological mapping and geophysical survey, a regional N-S fault and a secondary set of E-W local faults are identified in the vicinity of the resurgence area, which conjointly are likely to export groundwater from a neighbouring subcatchment up to the resurgence area. Downstream of the resurgence area, no significant change in the baseflow is observed, corresponding to the presence of an impermeable granitic pluton identified by the geological and geophysical mapping. Finally, a fractured zone in the Andean foothills is identified in the volcanic unit, which coincides with a perennial thermal spring, indicating upwelling flow and hydrogeological connectivity between the mountain block and the alluvial basin.The results strongly support the ability of the proposed methodology to identify geological structures that substantially impact the evolution of the baseflow through the catchment. The complementary multi-disciplinary methods are used innovatively to infer the link between geological and hydrogeological structures. The methodology does not aim to fully characterize the geological framework of the catchment but pragmatically focuses on hydrogeologically pertinent structures that may impact baseflow and consequently catchment management.