A Transboundary monitoring network for the management of the Classical karst aquifer.

The always increasing demand for good quality freshwater has ancient roots, and when the resource to be protect is a transboundary aquifer, the challenge is quite high, as the case of Classical Karst Reka/Timavo aquifer system, a shared aquifer between Italy and Slovenia. The importance of this water resource depends from the use of the resource itself. About the 20% of the waters exploited by AcegasApsAmga aqueduct for drinking purposes for the Trieste Province (Italy), belongs to the Reka/Timavo aquifer system. The remaining 80% is coming from the artesian wells of the Low Isonzo Plain. The 100% of the drinkwater withdrawals of Kraski Vodovod Sezana (the Slovenian aqueduct that serve Sesana and surroundings) is coming from the Classical Karst aquifer. Already the Resolution adopted by the General Assembly of the United Nations on 11 December 2008, on the low of transboundary aquifers (A/RES/63/124), emphasize the continuing importance of the codification and progressive development of international law aimed at the cross border protection of a so precious and fragile resource. In this framework fits the European HYDROKARST Interreg Project which aim is the knowledge of the Classical Karst aquifer system through the implementation of a jointed and stable water-monitoring network (www.hydrokarst-project.eu). A conscious protection of a resource pass through its knowledge so, a deep investigation was realized to understand the complexity of the hydrostructure. Classical Karst is a broad area shared between the northeastern Italian sector and the southwestern Slovenian side. The area is about 40 km long and 15 wide (SE-NW direction) bounded by the Isonzo/Soča and Vipacco/Vipava rivers, by the Pivka River basin, Cicarija structure and the Gulf of Trieste. The plateau, slightly inclined towards NW, consists of limestones deeply karstified and dolostones. Rainfall and surface waters swallow in the karst bedrock, where a network of caves is developed, transferring vertically the waters through the epikarst and vadose zone and collecting them in the aquifer characterized by large conduits quickly transporting the waters to the spring’s area. The fragility of the area is clarified by the well-developed mature karst and by the more of 5000 caves present over a surface of about 750 km2. In collaboration with the Slovenian partners 10 among caves, wells and springs were instrumented with in continuous datalogger devices. On about 40 points, in different flow water regimes, were collected water samples devoted to chemical, geochemical, microbiological and fauna analysis. The shared GeoDatabase collecting all the available and newly obtained geological, hydrological, hydrodynamic, geochemical and biological data, and all the maps realized are the common base to prepare cooperation agreements able to promote and implement action focused on the safe guards zone identification and realization. This common vision implements strategies able to prevent and/or reduce risks in emergencies in order to improve the drinking water quality, ensuring to the future generations, an abundance of good quality freshwaters.