The problem of self-similar flat spreading of groundwater mound in porous stratum bounded by impermeable bed in the presence of constant in time and localized in space source of liquid has been considered. Basing on dimension analysis method, the problem was reduced to ordinary differential equations. One-dimensional and two-dimensional cylindrically symmetrical cases were investigated. Intermediate asymptotics for pressure head distribution was obtained, and limits to applicability of solutions were analyzed.