To efficiently install emergency SABO facilities, the runoff sediment volume from rainfall after debris flow must be predicted. The relation between runoff sediment volume and rainfall as well as the factors controlling runoff sediment volume must be determined for such predictions. One such factor is the sediment volume remaining in the catchment. Therefore, we investigated the relations between (1) rainfall and runoff sediment volume and (2) runoff sediment volume and the remaining sediment volume in the catchment. This study targeted, 48 catchments in the Akatani River basin, Fukuoka Prefecture, Japan, where debris flow simultaneously occurred in July 2017. Moreover, three runoff sediment cases that occurred between 2018 and 2020 were considered. Differential analysis of aerial LiDAR survey data was performed to calculate runoff sediment volume and remaining sediment volume in the catchments. The results revealed that for (1), the July 2018 and August 2019 rainfalls had the same return period of 5―10 years, however, the runoff sediment volume from the August 2019 rainfall was lower than that from the July 2018 rainfall. Moreover, the runoff sediment volume from the July 2020 rainfall with a 30-50 year return period was higher than that from the August 2019 rainfall with a 5-10 year return period. Furthermore, for (2), the correlation coefficient between the runoff sediment volume from the July 2018 rainfall and the remaining sediment volume in the catchment was 0.65. The runoff sediment volume from the July 2020 rainfall was higher in the catchments containing granodiorite than in those without granodiorite.