engleski

Geomorphology and Hydrogeological Features of the Rječina Karst Spring-Croatia

Geomorphology and Hydrogeological Features of the Rječina Karst Spring - Croatia Abstract: The Rječina spring is one of the major springs in the Dinaric Karst. The spring occurs approximately 10 km in the north from the town of Rijeka, 325 m above sea level and offers an outstanding opportunity to cover gravitationally the public water demand of a town of about 200, 000 inhabitants, and the tourist needs of the whole region, with a groundwater of excellent quality. The spring appears at the tectonic contact between permeable Cretaceous carbonates and impermeable Paleogene clastic rocks, with a maximal discharge of 120 m3/s, but it is inactive during the summer dry seasons for up to three months a year. Over the past few decades, the spring and its catchment areas were the subject of comprehensive hydrogeological investigations. Part of these studies have been caving and cave-diving investigations that contributed to a better knowledge of spring cave geomorphology, and ultimately a better understanding of its hydrogeological features. Groundwater at the Rječina spring discharges from the approximately 300 m long cave, which consists of two main branches. The Upper channel morphology has characteristics of epiphreatic development while the Lower channel is more of artesian (Vauclusian) structure. The research results show that Upper and Lower inlet channels of the spring are hydraulically separated and probably connected to the different drainage systems, i.e. different retention areas. In the dry period both underground canals have no direct connection with the retention areas and the water present in the spring is only the rest of the last outflow detained in the cave channels. The recession coefficient obtained from hydrograph analysis indicates the lack of the base-flow spring component, and only fast-flow component was determined. Flow model calculations were conducted for 18O with the exponential (EM) and dispersion model (DM). The obtained mean residence time (MRT) of 3.6 months confirms dominant recent groundwater recharge.

Karst spring, geomorphology, hydrogeology, Rječina, Croatia

nije evidentirano