Time series analysis, modelling and assessment of optimal exploitation of the Nemanja karst springs, Serbia

The time series analysis was applied in the case-study of a karst aquifer in Serbia in order to study its functioning, hydrody­namic behavior and hydraulic properties. Focusing on the defi­nition of groundwater budget, due to very complex function­ing of karst systems the correlation and spectral analyses were used to emphasize the importance of transforming the input data – precipitation to effective infiltration. The characteriza­tion of karst aquifer was further improved by separating the output component – discharge to base-flow and fast-flow com­ponents. Additionally, the importance of these transformations was proved in application of the regression model for the sim­ulation of discharges based on the effective infiltration func­tions. A recharge-discharge model was applied in accordance withthe active groundwater management, defining optimal “exploitable” regimes, whichincluded the analyses of storage changes in karst water reservoirs under natural conditions, and calculation of the potential exploitation conditions

Vulnerability methods in hard rock formation as a basis for groundwater risk assessment – from resource to source

Groundwater in a hard rock formation is most endangered at places where a potential source can discharge contaminants that can reach the saturated zone of an aquifer. In these circumstances, an essential tool for groundwater protection is the contamination risk map. This map is based on the integration of two maps: a hazards map, i.e., map of potential sources of contamination and a vulnerability map. The selection of a proper vulnerability method is an important task since the resulting vulnerability map can significantly impact the final risk of contamination map. The most appropriate method for groundwater vulnerability assessment was considered in the case study of Tara National park, in Western Serbia. The four commonly used methods were applied to assess the intrinsic vulnerability maps: DRASTIC, EPIK, PI and COP. All the applied methods resulted in different vulnerability maps in assessing the degree of vulnerability, consequently influencing the groundwater contamination risk maps. The applied research presents an example of how contamination risk should be assessed in a specific area. Comparison of the results obtained for the area of Tara National Park indicates the preference of the PI method as a well-balanced method, taking into account all the specifics of the study area. A detailed analysis of the assessed risks in the catchments of the existing sources was also conducted to indicate probable sources of contamination and confirm the degree of accuracy of the created vulnerability and risk maps. The conducted research emphasizes the necessity to adopt a clear conceptual hydrogeological model and to apply several methods simultaneously to determine the optimal one for each individual area

An impact of tectonic structures on the groundwater circulation and losses from surface accumulation in the area of the left bank of Lazići dam on the Tara MTS

The process of water leakage determination in the area of water accumulation and left bank of the Lazići dam requires extensive application of different methods: very detailed monitoring data, tracing, structural and tectonic investigations, etc. Obtained results of water losses from the reservoir indicate a tendency for further increases. According to the applied analyses, two zones at the narrow zone of the grout curtain, characterized by different hydraulic mechanisms were detected. Additionally, the general direction of water leakage from the reservoir was detected. An important conclusion is that in such hydraulically intense conditions leakage is unstoppable, but can be partially controlled or slowed down

Analysis of the utility and management of karst underground reservoirs: case study of the Perucac karst spring

The construction of an underground dam and reservoir to provide an artificial water storage and karst control groundwater discharge regime is one of the most complex systems of tapping structure in karst. There are not many examples of underground dams, which increase the importance of risk management in their construction. This study proposes a procedure for constructing the underground karst reservoirs, focusing on the example of Perucac spring located in the Dinaric karst in Western Serbia. Possible effects of building of the underground reservoir are analyzed and a solution for a tapping structure is proposed. The applied concept is based on the karst groundwater budget, which provides valuable information on storage changes in the karst aquifer, enables further predictions of the optimal exploitation rate, and facilitates karst groundwater management. The results of this study give a basis for several possible technical solutions for a future tapping structure. These solutions were additionally analyzed in the process of multicriterial ranking to find the optimal process

High rate of native arteriovenous fistulas: How to reach this goal?

The types of vascular accesses for hemodialysis (HD) include the native arteriovenous fistula (AVF), arteriovenous graft (AVG) and central venous catheter (CVC). Adequately matured native AVF is the best choice for HD patients and a high percentage of its presence is the goal of every nephrologist and vascular surgeon. This paper analyses the number and type of vascular accesses for HD performed over a 10-year period at the Clinical Center of Serbia, and presents the factors of importance for the creation of such a high number of successful native AVF (over 80%). Such a result is, inter alia, the consequence of the appointment of the Vascular Access Coordinator, whose task was to improve the quality of care of blood vessels in the predialysis period as well as of functional vascular accesses, and to promote the cooperation among different specialists within the field. Vascular access is the “lifeline” for HD patients. Thus, its successful planning, creation and monitoring of vascular access is a continuous process that requires the collaboration and cooperation of the patient, nephrologist, vascular surgeon, radiologist and medical personnel