Hydraulic conductivity characteristics in mountains and implications for conceptualizing bedrock groundwater flow | Caractéristiques de la conductivité hydraulique en région de montagne et implications pour la conceptualisation des écoulements souterraines dans la roche en place Características de la conductividad hidráulica en montañas e implicancias para conceptualizar el flujo del agua subterránea en el basamento 山区水力传导率特征及在概念化基岩地下水流中的含意 Condutividades hidráulicas típicas em montanhas e implicações para a concetualização do escoamento subterrâneo no bedrock
2014
Welch, L. A. | Allen, D. M.
Influences of hydraulic conductivity (K) heterogeneities on bedrock groundwater (BG) flow systems in mountainous topography are investigated using a conceptual 2D numerical modelling approach. A conceptual model for K heterogeneity in crystalline bedrock mountainous environments is developed based on a review of previous research, and represents heterogeneities due to weathering profile, bedrock fracture characteristics, and catchment-scale (∼0.1–1 km) structural features. Numerical groundwater modelling of K scenarios for hypothetical mountain catchment topography indicates that general characteristics of the BG flow directions are dominated by prominent topographic features. Within the modelled saturated BG flow system, ∼90 % or more of total BG flux is focussed within a fractured bedrock zone, extending to depths of ∼100–200 m below the ground surface, overlying lower-K bedrock. Structural features and heterogeneities, represented as discrete zones of higher or lower K relative to surrounding bedrock, locally influence BG flow, but do not influence general BG flow patterns or general positions of BG flow divides. This result is supported by similar BG transit-time distribution shapes and statistics for systems with and without structural features. The results support the development of topography-based methods for predicting general locations of BG flow-system boundaries in mountain regions.
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