ABSTRACT: This paper describes the possibility of increasing the catchments retention capacity due to of artificial groundwater storage within alluvial sediments of the river. Variations of the water level in adjoining river on the real examples of upper part of the Podlužianka stream (Hron river catchment) and Predmieranka stream (Kysuce river catchment) serve as a source of artificial infiltration and exfiltration. Small theoretical reservoirs (dams) prolong the accumulation of the water for seven days, followed by its depletion. Amount of water, which could theoretically infiltrate to the alluvial aquifer during simulated situation of high water level in the adjoining river, was calculated. Time period of the retention the given volume of water in the aquifer and the reactions of the groundwater level on the changes of the boundary condition were calculated as well.