Hydraulic Conductivity of a Fractured Media at Different Scales

High variability of the hydraulic conductivity because of geological media heterogeneity as well as the scale dependency is a well known issue. In fractured media, this variability is even harder to characterize as available theoretical framework assumes homogeneous media. Nevertheless, the increase of underground projects and the reported affectations in/to surface and groundwater resources claim efforts to a better understanding of fractured media groundwater hydraulics and proper quantification of environmental impacts caused by those activities. In this work we estimate the hydraulic conductivity of a highly fractured massif in the Colombian Andes over scales from 6 cm to 12 km. To do so, we performed laboratory measurements, re-analyzed hydraulic tests and calibrated 3D numerical models, using the La Línea tunnels as real scale laboratory. K values vary up to four orders of magnitude at each characteristic length scale and show an increase until the local scale, followed by a small decrease at regional scale. In this way, field and regional scales display the same orders of magnitude. Finally, we explore the up-scale of the K-values based on fractal concepts and propose a power-law relationship between the K parameter and the scale.