Groundwater recharge, transit and discharge areas for aquifers must be found. Their location depends on influence of the ground surface and the hydrographical network (rivers, lakes, sea). Commonly it is agreed that the recharge areas are located at hilly places where maximums of infiltration flows and piezometric groundwater levels coincide. For the hydrogeological model of Latvia LAMO such method was applied. The model provides results for a complex spatial hydrogeological system where conditions even within an aquifer may differ considerably. For this reason, the common method of finding recharge, transit and discharge areas fails to provide right results. The new method has been developed that is founded on appliance of ratio for velocities of vertical to horizontal groundwater flows. The resulting velocity of the vertical flow is found as the difference of velocities of flows on top and bottom surfaces of the aquifer. The ratio r is the non dimensional function. Its values r=1 and r=0 determine locations of boundaries for the recharge and discharge areas, accordingly. For the transit area 0<r<1. Within the recharge and discharge areas r>1 and r<1, correspondingly. The new method provides right results even for discontinuous aquifers where zones of its zero thickness appear. Within such zones r=0. The method will be applied as a tool for investigating the complex groundwater processes that are modelled by LAMO. The method was used for extra calibration of LAMO, in order to improve its results. The research was supported by the Latvian State Research Program EVIDEnT