Abstract. The production and transportation of sediment in mountainous areas caused by
extreme rainfall events that are triggered by climate change is a challenging problem,
especially in watersheds. To investigate this issue, the present study
adopted the scenario approach coupled with simulations using various models.
Upon careful model selection, the simulation of projected rainfall,
landslide, debris flow, and loss assessment was integrated by connecting the
models' input and output. The Xindian watershed upstream from Taipei, Taiwan,
was identified and two extreme rainfall scenarios from the late 20th and 21st
centuries were selected to compare the effects of climate change. Using
sequence simulations, the chain reaction and compounded disaster were
analysed. Moreover, the potential effects of slope land hazards were compared
for the present and future, and the likely impacts in the selected
watershed areas were discussed with respect to extreme climate. The results
established that the unstable sediment volume would increase by 28.81 % in
terms of the projected extreme event. The total economic losses caused by the
chain impacts of slope land disasters under climate change would be increased
to USD 358.25 million. Owing to the geographical environment of the Taipei
metropolitan area, the indirect losses of a water supply shortage caused by
slope land disasters would be more serious than direct losses. In particular,
avenues to ensure the availability of the water supply will be the most critical
disaster prevention topic in the event of a future slope land disaster. The
results obtained from this study are expected to be beneficial because they
provide critical information for devising long-term strategies to combat the
impacts of slope land disasters.