The book brings the analysis of relations between recharge and discharge of karst aquifers, i.e. input and output functions of karst system, which can be applied in order to define the characteristics of its functioning. Three different recharge-discharge models were set up. The functioning within the system was expressed by the transfer function between the input and the output signal, and the adequacy of individual models was evaluated according to the accuracy of the simulation, which is related to the transfer function’s ability to reproduce discharges, on the basis of which it was determined. The improvement in the model’s results, brought about by the introduction of the effective infiltration function instead of the precipitation, highlighted the significant influence exerted by the vegetation and processes in air and in the soil on the quantity and the temporal distribution of actually infiltrated water. Additionally, a specific hydrodynamic function of epikarst was proved, which, due to its typical structure, influences the temporal distribution of recharge.