Totally 40 debris flow torrents in the Zousui river basin were selected for numerical simulation to clarify sediment impact due to climate change. Rainfall data from the climate scenario representative concentration pathway (RCP) 8.5, generated through dynamic downscaling and bias correction, were used to simulate discharge through Hec-HMS and debris flow impacts through Flo-2D, as well as the variation in impact from the end of 20th century to the end of 21st century. The results indicate that total sediment impact by debris flow exhibited an increasing trend of approximately 11%. Thus, rainfall variation affects debris flow. This manifests not only among sub-catchments,
but also in the same sub-catchment, in that numerous sediments from torrents import to the main flow and affect the downstream area.
Key Words: Climate change scenario, debris flow impact, Flo-2D, sediment volume, sediment disaster susceptibility