Groundwater includes water located in deeper soil layers characterized by a complete saturation. The groundwater flow is divided to flow in saturated conditions and flow in unsaturated conditions. Water flow in unsaturated medium is primarily vertical and water flow in the saturated medium is primarily horizontal. Water flow models describe the groundwater flow and solute transport using mathematical equations based on certain simplified assumptions. In unsaturated soil zone modeling is more complex due to the constant change in soil moisture as a result of precipitation and groundwater level variations. Determining the water regime of the unsaturated soil zone, while taking into account the seasonal variations of groundwater levels at selected locations, were carried out using the HYDRUS-1D numerical model. The numerical model was tested using the data obtained from the lysimeters at five locations in the Biđ field (eastern Croatia). The model was successfully validated with a high level of confidence on lysimeter outflow (R2 = 0,87 – 0,96). Hydropedological soil properties were determined at five locations to determine soil water regime of the unsaturated soil zone considering seasonal variations of groundwater levels measured at the proximity of each location. Results show different groundwater levels at every location, which had a major influence on water content and pressure head oscillations in the upper soil layers. The low amount of precipitation in the observed year resulted in even larger effect of groundwater levels at the experimental sites. Results highlight the importance of groundwater resources in agricultural production because of their significant influence on soil surface layer, especially when irrigation practices are needed.