This study aimed to examine the potential for using Cs-137 and Be-7 to identify the sources of sediment based on the different penetration depth of both radio nuclides. A large scale sprinkling experiments (94m²) has been undertaken to obtain the sediment generated from overlandflow and pipe flow. At the initial part of the experiment, both Cs-137 and Be-7 activities were high in the sediment from overland flow, but as the time passing Be-7 activity become much lower than the Cs-137 activity. Such differing responses suggested that the mode of erosion became from sheet erosion to rill erosion. The Be-7 and Cs-137 activity of pipe outflow sediment was low, suggesting that the sediment was derived from deeper part of the soil. Such information may allow the development of a practical technique for estimation the sources and predominant production processes of sediment using these isotopes.