Hydrogeological Assessment and Modified Conceptual Model of a Dinaric Karst Island Aquifer

Abstract

Vis Island is situated in southern Croatia. The island is mostly composed of karstified carbonate rocks and belongs to the Dinaric karst region, which is a locus typicus of karst landforms. Located far from the mainland, Vis island has maintained a successful water supply from its own karst aquifer for decades. Hydrogeological research has been undertaken to protect this excellent karst aquifer by establishing sanitary protection zones and to explore the possibility of increasing the pumping yield. New groundwater velocity data obtained via a tracer test were in accordance with the rock mass hydraulic conductivity calculated from previous pumping tests. The hydrochemical interpretation indicated several different phenomena, from carbonate and sulfate rock dissolution to seawater mixing with groundwater. A conceptual model of the island’s aquifer was improved, and two main catchments were delineated according to tracer test results, and connected with the geological setting, hydrochemical data, and new climatological insights. Such an approach is applicable for similar karst aquifers, in which topographic and hydrogeological divides usually do not coincide.

Multidisciplinary investigations of a karst reservoir for managed aquifer recharge applications on the island of Vis (Croatia)

“…The Korita aquifer is protected from seawater intrusions and has excellent water quality, making it the most suitable and safe for MAR implementation. A sufficient storage capacity was evidenced by the high transmissivity values (Terzić et al 2022) that also suggested a homogenous groundwater flow through a densely fractured, "porous-like" aquifer. These characteristics are favorable since they allow a diffuse infiltration without a quick discharge toward the sea through large karstic conduits.…”

“…Overall, the onshore structure of Vis is an open anticline with an axial plane striking E-W and hinge dipping towards the E. The anticline is bounded to the N and S by the Oključna and Podšpilje-Rukavac faults, respectively. Terzić (2004) and Terzić et al (2022) provided a detailed description of the hydrogeological setting of the Vis island and assessed its freshwater resources. The main conclusions were:…”

“…The maximum pumping capacity at Korita is 42 l/s, and the groundwater is pumped from the approximate depth of 110 to 140 m. Groundwater levels vary between 10-20 m a.s.l. depending on the well location and pumping quantity (Terzić et al 2022). Groundwater quality is excellent since hydrogeological barriers protect it from seawater intrusion.…”

Feasibility Study of Managed Aquifer Recharge Deployment on the Island of Vis (Croatia)

“…This pressure is enhanced by the concomitant sudden increase in tourist arrivals and prolonged droughts during the summer months, as well as the precipitation decrease and the increasing frequency and intensity of storms during winter months. Furthermore, most of Croatia's coastal and island aquifers are karst aquifers [18], with a heterogeneous permeability field fostered by large conduits being a preferential path for seawater infiltration. In such aquifers, the underground mixing of seawater and groundwater forms wide transition zones and wedges.…”

“…In this case, the MAR concept is based on the recharge of the karst aquifer by the infiltration pond method, commonly used to recharge unconfined aquifers. The aim of MAR is to enhance and secure the quantitative status of groundwater resources in a karst aquifer, which endures high stresses during the dry In particular, the island of Vis was chosen due to its autonomy in terms of water supp which is uncommon for most islands in the Adriatic and Mediterranean seas [18][19][20][21]. Ho ever, the karstic aquifer from which the groundwater is abstracted, as mentioned above under considerable stress during the dry summer season, and reductions for consum In particular, the island of Vis was chosen due to its autonomy in terms of water supply, which is uncommon for most islands in the Adriatic and Mediterranean seas [18][19][20][21].…”