Hydrodynamics of Flow

Abstract

Flow of groundwater in karst areas covers a wide field of hydrodynamic conditions. There is diffuse flow through partings in the rocks, such as joints or beddings, which initially, i.e. prior to widening by dissolution, might have apertures as small as 2 × 10−3 cm (Davis 1968). To describe the hydrodynamic properties of these pathways of flow, one may visualize these partings either as two parallel planes with a fixed distance, or as a two-dimensional porous medium. In any case flow is laminar and flow velocities are small, in the order of 10−3 cm s−1. Thus, diffuse flow is characterized by a long retention time of karst water in the rock. The springs fed by this kind of water, which has sufficient time to equilibrate with respect temperature and chemical composition, usually show only small variations in temperature and are close to calcite saturation. Due to the long retention time of water and the large storage volume of the aquifer, they react slowly to flood pulses.