The climate change for flood and debris mitigation after typhoon Morakot 2009 in Taiwan

摘要

The typhoon Morakot struck Taiwan during August 8–10, 2009, and the government statistics analyzed that typhoon brought maximum 3,004mm in three days, and 21 rain stations is over 2,000mm. It claimed 673 casualties, 26 missing persons and 24,950 evacuees are evacuated by the Disaster Prevention and Response Act. The heavy and log period rainfall also triggered multi-hazards; such as: flooding, debris flow and deep landslides, and the economic loss is 6.2billion USD. This kind damage is extreme weather, and we think that climate change will bring huge impacts to nations all over the world. Those impacts including the followings: change in biosphere, long-duration drought, large floods trigger by extreme torrential rain, spatial change in homelands, and food scarcity. The extreme weather induced by climate change is the most direct factor influencing the floods, e.g. the extreme rainfall increases discharge and inundation area, sea level and estuary water level raising induce overbank floods, and land-use abuse and land-slides trigger high concentration of sediment discharge and river bed aggradations. This study aims at the settings of hydrological scenarios due to climate change, evaluation of hydraulic structures (e.g. levees), vulnerability and risk analysis, and adaption strategy and practices. The study area is focused on Kaoping River basin watershed. First, the hydrological scenarios due to climate change are set. Secondly, based on those scenarios, the hydraulic structures are evaluated. Thirdly, the vulnerability and risk analysis are performed. Last, adaption strategy and action plans are proposed by referencing to actions taken by the Netherlands, Japan and USA for improving the capacity of the hydraulic structures of this basin watershed.