This master thesis deals with hydrogeological characteristics of Kopački rit, a special nature reserve located in Baranja. The aim of the research is to analyze geomechanical properties of the materials from borehole cores in order to determine hydrogeological properties of the Quaternary deposits and to correlate them with the results of well pumping test interpretations. Two methods, the Kozeny-Carman model and correlation analyses, are used to determine the specific surface area and hydraulic conductivity of the deposits. The results of the analysis confirm the predicted specific surface area of the covering deposits and the corresponding hydraulic conductivity of the Quaternary deposits, which significantly affects the quantity and quality of groundwater in this area. The analysis also shows that the semi-permeable covering deposits provide limited protection from potential contamination because of their thinness and low specific surface area, consistent with the granulometric composition of the material. The obtained results provide valuable information for further research and the development of strategies for the conservation and management of water resources in Kopački rit, with a particular emphasis on contamination protection and groundwater quality maintenance.