Potential Impact of Climate Change and Extreme Events on Slope Land Hazard – A Case Study of Xindian Watershed in Taiwan

Abstract

Abstract. The production and transportation of sediment in mountainous areas caused by extreme rainfall events 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 were integrated by connecting the models' input and output. The Xindian 10 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 between 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 15 economic losses caused by the chain impacts of slope land disasters under climate change would be increased to US$ 358.25 million. Owing to the geographical environment of the Taipei metropolitan area, the indirect losses of water supply shortage caused by slope land disasters would be more serious than direct losses. In particular, avenues to ensure the availability of 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 20 combat the impacts of slope land disasters.