New insights into factors controlling the underground drainage of South Supramonte (Sardinia, Italy) from dye-tracing tests

The recent exploration of a new sinkhole found along the Flumineddu fluviokarst canyon (Sardinia, Italy) has presented the opportunity to investigate a further segment of the Supramonte karst aquifer. In this work, the result of a dye-tracing test performed in the Piggios de Janas Cave is presented together with an updated view on the current understanding of the hydrogeology of this area. A water connection between this new discovery and Su Colostrargiu Cave has been detected, unveiling another part of the S'Edera-Su Gologone karst system. Furthermore, three distinct groundwater drainages have been recognized at 250, 450 and 650 m asl, within S'Eni 'e Istettai Cave, S'Orale 'e Su Mudrecu Cave and Su Colostrargiu Cave, respectively. Within each of these caves a river flows in vadose conduits developed along the main fractures, parallel to each other, but at different altitudes determined by the fault-dislocated basement position.