During field researches performed in natural conditions of Chernobyl 30-km exclusion zone the redistribution of radionuclides with surface runoff and their downgoing transport with infiltration water have been studied. Observations for solid and liquid phase transport have been performed at natural field observation plot equipped with measuring moisture flow and meteorological devices. Observations were conducted during 3 years, and a one-year control experiment with intensive artificial rainfalls then was implemented to study the surface lateral (erosion runoff) and vertical downward transport of radionuclides (137Cs, 90Sr). Balance modeling assessment is done in order to evaluate the role of surface redistribution and vertical downgoing transport of long-lived radionuclides in autorehabilitation of contaminated areas.