Hydrogeologic Behavior of a Complex and Mature Karst Aquifer System under Drought Condition

This paper aims, using classic hydrogeologic techniques, Time Series Analysis, Principal Component Analysis, Standardized Precipitation Index, and MRC methods to better understand the hydrogeological, and hydraulic characteristics of a mature karst aquifer system, and to analyze its behavior under drought conditions. The study area is the karst aquifer system of Aggitis (AAS), Northern East Greece, characterized by a mountainous terrain consisting of highly fissured and karstified Falakro marbles of Mesozoic age. AAS catchment extends 63.4 km² and exhibits a duality of conduit and/or diffuse flow model. AAS is drained by the permanent large Maaras spring with a mean annual value of 4.656 m³/s. The dominant chemical type is Ca-HCO₃. PCA and hydrochemical analysis were effectively used in combination to interpret the main hydrogeochemical mechanisms controlling karst water quality. A combined methodology provides a useful and effective tool for assessing the characteristic behavior of karst springs under drought conditions. It enables also, to gain insight into the prevailing processes in a karst aquifer system. The statistical analysis of hydrological data revealed the karst system is mainly recharged by diffuse infiltration.