GROUND WATER IN FRACTURED CARBONATE ROCKS: THE LEGACY OF RICHARD PARIZEK

Forty years ago, L.H. Lattman and R.R. Parizek wrote what has become a classic paper on developing water resources in carbonate aquifers by drilling wells on fracture trace intersections. This paper is a milestone in the evolution of karst hydrogeology because it was one of the first to recognize the extremely anisotropic permeability of carbonate rock. The implications were extensive and are still being developed. The present paper traces developments in karst hydrogeology that have roots in the Lattman-Parizek paper. Fractures occur as isolated joints and as fracture swarms. The effective aperture and connectivity of fracture sets combined with hydraulic gradients determine the pathways that eventually evolve into conduits. The mechanisms of fracture enlargement in response to gradient and water chemistry have been worked out in elegant detail. Age and tectonic origins of fractures determine their importance as flow paths with old mineralized fractures less important and young fractures from modern tectonic movements or stress release fracturing more important. The role of fractures varies with geologic setting. Fractures appear at their most dramatic in alpine cave systems where efficient internal drainage of entire mountains is through great shafts with collective depths measured in kilometers. In plateau settings permeability may be dominated by bedding plane partings so that master conduit systems may have no surface expression in fracture traces.