Measured precipitation vs. effective infiltration and their influence on the assessment of karst systems based on results of the time series analysis

Karst aquifers are characterized by high heterogeneity and spatial variability of hydrogeological parameters. One possible approach to study them is the time series analysis of the recharge and discharge data as the input and output functions of the system. But the interpretation of obtained results in the sense of understanding of the functioning of karst system is very difficult and the findings are often not properly validated. One way of testing the results is to apply the method on various test areas with different characteristics. Therefore, for the purpose of this study we selected four karst aquifers with well-known characteristics – two of them on Slovene and two on Serbian karst. They differ above all in the characteristics of recharge, the extent of the catchment, and the degree of karstification. Based on the comparison of obtained results it was possible to draw inferences about these characteristics and the capability of the applied time series analysis to reflect and demonstrate them. We used the effective infiltration as the input function instead of precipitation in order to take into consideration various processes in air, vegetation and soil and their influence on the recharge, and to separate them from the processes within the karst aquifer. The results of the study confirm that for the assessment of the karst system structure it is essential to consider the effective infiltration as the input function instead of precipitation. Still the largest differences between the results of the applied time series analysis on four studied karst aquifers are due to their different structures, degrees of karstification and characteristics of groundwater flow.