Modelling of karst genesis at the catchment scale – influence of spatially variable hydraulic conductivity

Abstract

The aim of this work is to study the genesis of karst aquifers at the catchment scale. Especially the influence of different boundary conditions and geological setting is investigated in several scenarios. A hybrid continuum-discrete flow model is used for the modelling of conduit development. Effects of heterogeneity in hydraulic conductivity and in fracture spacing are examined in four scenarios. For homogeneous conditions a shallow water-table cave develops. If an area of reduced hydraulic conductivity is introduced, the conduit system evolves around this area and a deep phreatic cave is formed. This is true only, if the contrast in hydraulic conductivity is large enough. If an area of higher fracture density is introduced, this area is more intensely karstified, and a local system of deep karstification develops.