Groundwater flow in river valley aquifer is shaped by stresses, which intensity is variable during time. In this case high accuracy of mathematical model demands calculations for transient flow. In this convention was executed model of groundwater flow for the part of the Vistula river valley (central Poland). Aquifer is built of sandily-gravelly sediments of high permeability, which thickness arrives at 40 meters. A numerical finite difference model were built using Visual Modflow software. Discretization of the space in the horizontal surface was executed by orthogonal net, divisive the area on square blocks of 10 meters side length. It were distinguished 10 layers of diverse thickness. Oscillations of surface water level and distribution of recharge were treated as the main criterion for stressperiods marking. After putting of all parameters model was calibrated. The main result of calculations is the spatiotemporal variability of the hydrokinetic state of the aquifer, what gave the base for mass balance computation.