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Heterogeneity of the aquifers is one of the key factors that control transport processes in groundwater. It is defined by the spatial distribution of hydofacies-sedimentsformed in characteristic depositional environments and have typical hydrogeological properties. Due to the (in time and space) changing sedimetological conditions, is the distribution of hydrofacies in nature often complex and difficulttodefine.The difficulty of this procedure most of ten limits reliability and consequently applicability of numerical transport models. For the purposes of improvement of reliability of hydrological modelling in the area of alluvial deposits of Ljubljana polje a hydrogeological model was constructed. It is based on the borehole logs, supplemented with geological conceptual information and geostatistical methods, combined with Markov chain models. The model consists of four units - hydrofacies with different volume tricportions (Gravel 45 %, Silt and clay with gravel 36 %, Silt and clay 5 % and Conglomerate 14 %). The used approach enables development of a set of equally probable realisations of spatial distribution of hydrofacies that are conditioned to the borehole data and represent geologically plausible image of the heterogeneity of the aquifer.