 The JANAF system also includes a petroleum derivatives pipeline to a fuel handling terminal in Zagreb.The region forms a center of Croatia's natural gas supply system, based on an underground storage facility located approximately east of Zagreb.The Dinaric mountain ranges of Lika and Gorski Kotar in the region's western reaches represent a natural barrier between the Adriatic Sea to its west and the Pannonian Basin and to its east, traversed by few high-performance transport routes until recently.