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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/94577

    Title: HHT與熵理論應用於荖濃溪流域颱風降雨特性之分析
    Other Titles: Analysis of typhoon characteristics for Laonong River basin based on Hilbert-Huang transform and entropy theory
    Authors: 羅凱文;Lo, Kai-Wen
    Contributors: 淡江大學水資源及環境工程學系碩士班
    黃富國;Huang, Fu-Kuo
    Keywords: 荖濃溪流域;颱風;希爾伯特-黃轉換;;時頻分析;Laonong river basin;typhoon;HHT;Entropy;time-frequency analysis
    Date: 2013
    Issue Date: 2014-01-23 14:47:19 (UTC+8)
    Abstract: 台灣位於北太平洋西部熱帶氣旋活躍之海域,近年的莫拉克颱風為台灣創下50年來最嚴重的水災,因此鑒於颱風對台灣造成的災損如此嚴重,實有必要對颱風特性有進一步的了解。本研究為了解荖濃溪流域颱風降雨時空分布之非線性及非穩態等特性,採用具有完全自適性,且適合處理突變訊號之希爾伯特-黃轉換(HHT)來進行分析。另有別於一般時頻圖使用目視判定法,本研究引用度量訊息不確定性之熵值(entropy)來量化水文訊號之時頻特徵,並將其應用於荖濃溪流域之颱風降雨特性分析,展現了探究水文時頻特性之另一可行途徑。
    Taiwan is located in the western North Pacific–East Asian (WNP-EA) sector. Over the WNP-EA region, typhoon is one of the most important systems for producing heavy precipitation that will cause serious damages. The exploration of typhoon characteristics becomes an importment issue thus. In order to investigate the characteristics of typhoon rainfall with non-linear and non-stationary in nature, a relatively new method of Hilbert-Huang transform (HHT) will be used to carry out the time-frequency analysis. Traditionally, the HHT spectrogram is explained by visual inspection. To improve the problems, the entropy that can measure the signal uncertainty will be utilized to quantify the time-frequency signal characteristics of typhoon rainfall. The combined HHT-entropy method is used to examine the typhoon rainfall characteristics of the Laonong River Basin in the southern Taiwan in this study.
    The result according to the rainfall characteristics of 10 typhoons in Laonong River Basin shows that the variation in entropy of typhoon rainfall is a good indicator for slope disaster prevention. By the overlay map between typhoon entropy isopleth map and landslide potential map, we can know where the high-risk areas are easily. The relationship between entropy and rainfall parameters can be summarized that the greater entropy comes the greater typhoon rainfall duration and cumulative rainfall will be, but the relationship between entropy and rainfall intensity is less obvious. According to characteristics of the entropy and the typhoon rainfall distribution, it shows that high entropy is due to the high uncertainty in rainfall, which means the rapid fluctuation in rainfall; and low entropy is due to the low uncertainty in rainfall, which means the rainfall is more concentrated. In addition, the analysis of rainfall pattern shows the main rainfall pattern in Laonong River Basin is peak at the center. This rainfall pattern has a characteristic the groundwater is easy to accumulate with high rainfall entropy, which in turn will easily lead to landslides and debris flows because of the reduction of slope stability. Thus, more attention should be paid on this situation.
    Appears in Collections:[水資源及環境工程學系暨研究所] 學位論文

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