Glossary of Karst and Cave Terms
1. The ratio, usually expressed as a percentage of the total volume of voids available for fluid transmission to the total volume of the porous medium . 2. The ratio of the volume of the voids of a soil or rock mass that can be drained by gravity to the total volume of the mass . 3. The amount of interconnected pore space and fracture openings available for the transmission of fluids, expressed as the ratio of the volume of interconnected pores and openings to the volume of rock. See also porosity; porosity, primary; porosity, secondary; porosity, tertiary.