Conceptual Model Suitability for Reproducing Preferential Flow in Waste Rock

Stefan Broda, Daniela Blessent, and Michel Aubertin

Keywords

numerical modeling, mine waste rock, preferential flow, macropores, fractures

Abstract

This study describes the first-time application of modelling approaches designed for groundwater flow in fractured massive rock aquifers to reproduce preferential flow triggered by macropores and fractures in waste rock material, using the 3D numerical HydroGeoSphere model. Besides the common equivalent porous media conceptual approach, the dual continuum and discrete random fracture approach were tested for reproducing distinct, predominantly macroporeand porous media-driven outflows observed at an intermediate laboratory scale experiment. Outflows obtained with the numerical model applying the basic equivalent porous media approach could not cover the macropore-driven drainage period. Increasing model complexity improved model accuracy in terms of reproducing onset of observed drainage periods and total cumulative volumes. However, observed distinct discharge periods and discharge pausing could not be depicted with the numerical model, independently of the conceptual model applied. A sensitivity analysis concludes this study, indicating the necessity of improving knowledge on principal model parameters, such as fracture aperture and location.

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