| Summary: | 碩士 === 淡江大學 === 水資源及環境工程學系碩士班 === 102 === Taiwan is among the most active tropical cyclone regions in the world. There are several typhoons hit Taiwan every year. Especially in 2009, typhoon Morakot brought a significant disaster in Taiwan. Due to the serious damages caused by typhoons, it is necessary to explore the characteristics of typhoons. In order to understand the characteristics of rainfall of typhoon, the method of empirical mode decomposition (EMD) in Hilbert-Huang transform (HHT), able to consider the non-linear and non-stationary nature of signal, is adopted in this study. On the other hand, the method of empirical orthogonal function (EOF) analysis, usually used in atmospheric sciences, is also employed to analyze the spatiotemporal characteristics of typhoon rainfall. In addition, the data of Laonong River Basin is taken for example to investigate the temporal and spatial distribution of typhoon rainfall.
According to the analysis results of 10 typhoons in Laonong River Basin, it shows that the expansion coefficients associated with the EOF can reflect the variation of typhoon rainfall with time appropriately. In addition, the spatial distribution of rainfall can be depicted clearly by the first few spatial modes of EOF. By overlapping the map of EOF isopleth and the map of potential debris flow torrent, or the landslide potential map, we can easily identify where the high-risk hazard areas are. The results in this study can be used as an indicator for risk management and as a tool to develop practical strategies for disaster prevention, such as mitigation of landslides and debris flow.
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