Evaluation of the Impact of Climate Change and Land Subsidence on Flood Hazard in Coastal Lowlands of Southwestern Taiwan

• Main Authors: Chia-Ho Wang, 王嘉和
• Other Authors: Tsang-Jung Chang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/23674529816454582160

碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 96 === Recently, it has been confirmed that climate change has induced sea level rises and extreme rainfalls, resulting in more serious flood and inundation disasters, especially in the coastal lowlands in Taiwan. Climate change has great impact on the safety of the hydraulic infrastructure, which was built from 1970s. The main objective of this paper is to investigate the evaluation method for assessing the impact of climate change on flood hazard in the coastal lowlands of Taiwan. The paper selects Hebauyu watershed of Chiayi County as the demonstration area. The inundation-related information, such as geographic situation, hydrologic data, surface drainage system, storm sewer system etc., is collected. The newly updated DTM data in 2006 is used in the present study as well. An integrated numerical model is herein developed to assess the impact of climate change on flood hazard in the coastal lowlands, based on the extension of the 1-D river routing model and the 2-D inundation routing model. Next a series of inundation simulations of the coastal lowlands are conducted for various scenarios caused by the extreme rainfall event in the upstream watershed and the highest sea level rise in downstream, respectively. The inundation loss and risk for various scenarios are analyzed as well. Finally, the worst case of the climate-change-induced inundation scenarios is studied. The possible adaptation strategies, including the engineering and non-engineering measures, for alleviating the impact of climate change on flood hazard are proposed. In comparison with the results of three GCMs with various emission scenarios, it is found that the amounts of future precipitation calculated by the above three GCMs give different tendency, indicating that there exists some uncertainty in this topics. On the other hand, all of the three GCMs demonstrate the similar tendency of sea level rises with limited variation. Taking the A2 scenario of HADCM3 model as example, which results in the increases of precipitation and sea level rises, for the case considering both of climate change and land subsidence, the simulated results show that serious over-banking flow will both happen in 2010 to 2039 and in 2040 to 2069, and very serious over-banking flow will occur in 2070 to 2099.