Extreme typhoon events have been increasing due to climate change. In recent years, severe landslides, flooding, and extreme sediment transport have become more easily induced by these events. This study employs dynamic downscaling climate projection data to evaluate riverbed changes and sediment transport processes of the Gaoping River, located in southern Taiwan, under the worst late 20th century conditions and projections for the late 21st century. Results show that the peak runoff discharge in the late 21st century could be 1.48 times larger than that in the late 20th century. This data indicates that the risk potential for overbank and pier scour disasters will increase in the future. However, in contrast to the late 20th century, the thalweg sediment aggradation model indicated 19% less in the late 21st century. An experimental design method was applied to further explore the reasons behind this outKome. It was found that severe riverbed changes correlated negatively with the peak discharge in extreme floods. These findings will greatly assist in understanding riverbed change processes under extreme typhoon events using dynamic downscaling climate change data.