Numerical modelling and groundwater analysis in the Vuka river basin

3D numerical models of groundwater flow are characterised by great complexity and numerous input data but also high applicability. The paper presents groundwater modelling in the Vuka river basin in eastern Croatia. The key features of this area are automorphic and hydromorphic soils, vertical and horizontal heterogeneity of geological strata, vegetation cover and numerous rivers and canals. Following the establishment of the conceptual model, we turned it into a numerical model using appropriate mathematical expressions. After the model calibration, we conducted a parameter analysis that revealed infiltration as having the highest impact on the flow in the analysed conditions, which was determined as 17% of the total precipitation that occurred in the river basin by the calibration. This is important data since the observed soil types are recharged mostly through precipitation, but also for purposes of water balance calculation. The parameter analysis showed that evapotranspiration has very low impact on the final result in such models despite 70 % vegetation cover in the basin.