Physical and analytical modeling of rhythmic karst springs

Rhythmic Karst Springs (RKSs) are rare geologic features that rhythmically outflow water. A mechanical model for the rhythmic flow with rhythmic spill-over configuration was constructed in this work. The evolution of the RKS was revealed by using geological process analysis. The analytical model can directly explain the existence of RKSs in soluble rock regions and their formation mechanism in nature. Visual observations and flow measurements were performed using a laboratory physical model of RKS. The physical model components included a soluble rock simulation area, karst pipes, cave-reservoir, karst depression terrain, water tank, rhythmic spring, and the outflow measurement system. Groups of tests were carried out to recreate the process of RKS functioning and to confirm the rhythmic cycle duration and the threshold of replenishment intensity. This research helped to interpret the behavior of rhythmic springs using the recharge and evacuation of the subsurface cave-reservoir by means of fluid mechanics and groundwater hydraulics theories.