The Potential Assessment of Environmental Disasters for Remoted Mountainous Communities nearby the Riverbank in Southern Taiwan under Climate Change

There are almost 24% of total remoted mountainous communities located in Chiayi, Tainan, Kaohsiung and Pingtung counties/cities of southern Taiwan. During recent years, the extreme rainfall events brought huge amounts of rainfall and triggered severe environmental disasters such as landslides, debris flows, flooding and sediment disasters in southern Taiwan. The maximum rainfall of typhoon Morakot in August 2009 was approaching 3,000 mm during 4 days in mountainous area of Chiayi city. There are 359 landslides occurred nearby the remoted mountainous communities in the study area during the typhoon event. The landslide area was over 900 ha.

The potential assessments of environmental disasters for 38 remoted mountainous communities nearby the riverbank were analyzed. The landslide areas nearby the 38 communities in last 10 years (2007-2016) were identified. The numerical models (HEC-RAS, CCHE-2D and FLO-2D) were used to simulate the flooding level, scouring and deposition of river bed and the influence area of debris-flow occurrence under different return periods (25, 50 and 100 years). The results show that there are 5, 4 and 14 high potential communities of landslide, flooding and debris flow disasters, respectively. The results proposed by this study can provide the disaster risk management of administrative decisions to lessen the impacts of environmental disasters for remoted mountainous communities nearby the riverbank in southern Taiwan under climate change.