This paper studies the statistics and tectonism of a multiscale natural fracture system in limestone. The fracture network exhibits a self‐similar characteristic with a correlation between its power law length exponent a and fractal dimension D, i.e., a ≈ D + 1. Contradicting the scale‐invariant connectivity of idealized self‐similar systems, the percolation state of trace patterns mapped at different scales and localities of the study area varies significantly, from well to poorly connected. A tectonic interpretation based on a polyphase fracture network evolution history is proposed to explain this discrepancy. We present data to suggest that the driving force for fracture formation may be dissipated at the end of a tectonic event when the system becomes connected. However, the “effective” connectivity can successively be reduced by cementation of early fractures and reestablished by subsequent cracking, rendering a variable “apparent” connectivity that can be significantly above the percolation threshold.

We present a discussion of the state-of-the art on modelling geometrical characteristics, hydrogeological behavior and geochemical evolution of karst aquifers of meteoric origin. The considered key karst processes include: (1) the recharge processes, (2) the various hydrodynamic processes in the vadose and phreatic zones, (3) the related transport processes and (4) the speleogenesis processes. Different types of approaches for modelling geometrical characteristics of karst conduit networks are summarized. Integrated numerical studies on hydrogeological behavior of karst aquifers with functional and physically based models are then reviewed. Challenging issues in karst modelling are further discussed based on previous modelling progresses. The paper finally offers recommendations for advancing the modelling of hydrogeological behavior of karst systems and lists several open questions for future research.