Gully erosion, which develops within a short period on reclaimed farmland consisting of decomposed granite soil, causes large amounts of surface soil loss. This soil first flows into a channel, and the accumulated sediment, if it occurs, causes on overflow of surface water in the channel, leading to secondary erosion. On the other hand, a sedimentation tank or reservoir often becomes full of these soils for a short period and thus develops functional disorder.<BR>In this study, in order to deal with this situation, the actual conditions of gully erosion and sedimentation, occuring on reclaimed land consisting of decomposed granite soil, were surveyed to clarify the characteristics of soil movement by soil budget analysis for each soil grain size.<BR>Soil loss from the fields was calculated from the integration of gully cross-sections. Sediment volume was calculated by surveying the sedimentation forms. Furthermore, grain size compositions and dry densities for each soil layer were measured.<BR>Sedimentation occurred in channels with a low gradient of under 2 degrees, the sedimentation tank and the sedimentation reservoir. Along the channels, there were several sediment fans adjoining each other. In the sedimentation tank, a shallow cone-shaped sediment surface was observed. In the sedimentation reservoir, the sedimentation form was observed to consist of two tongueshaped shelves. The results of the soil budget analysis showed that the sediment in low gradient channels, which was mainly composed of gravel and sand fragments, was more abundant than that in the sedimentation tank which had accumulated silt and clay subsoil but had a generally wide grain size distribution. The sediment in the sedimentation reservoir, which had a large amount of gravel and sand fragments, as in the channels, had more silt and clay fragments than any other location. This indicated that the sedimentation reservoir acted as a retarding basin due to the fact the inflow of sediment had been reduced by the upstream sedimentation.<BR>Through this study, it was proposed that a channel with a low gradient should be converted to a belt-shaped sedimentation zone and that the arrangement, the structure and the capacity of sedimentation facilities should be designed from the viewpoint of efficient sedimentation in each case.