DESCRIPTION OF THE STUDY AREA
Vis is a small remote island on the Adriatic Sea and belongs to the group of the Middle Dalmatian islands. With an area of 89.7 km2, the island is mostly composed of karstified carbonate rocks and belongs to Dinaric karst region, locus typicus for karst landforms.
Vis is not connected to the mainland by submarine water pipeline so it has autonomous water supply due to favorable geological and hydrological conditions which enabled the formation of excellent karst aquifers.
Island’s landscape can be described as three hilly chains separated by two valleys. The northern valley is relatively narrow, tectonically predisposed and in this valley there is island’s most important water supply spot – the Korita wells. Southern valley is wider and karst poljes are developed.
All populated places on the island are connected to public water supply. The island of Vis has water supply from its own karst aquifer (drilled wells in location Korita and costal spring Pizdica). Pumping capacity of Pizdica is 3.3 L/s. In Korita pumping site the capacity is around 40 L/s. The main problem concerning water supply from island karst aquifers is high possibility of seawater intrusion. However, karst poljes, together with infilled rock mass below them, serve as a barrier to the see water intrusion from souther direction into the cental island karst aquifer. Western boundary is geologically clear and represented by volcanic-sedimentary-evaporite total barrier. That prevention of seawater penetration from two major sides is geological reason for such a high quality aquifer on this karstic island.