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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/88177

    Title: HHT與熵理論應用於荖濃溪流域降雨特性探討
    Other Titles: Research of hilbert-huang transform and entropy for rainfall characteristics in Laonong River Basin
    Authors: 哈元圓;Ha, Yuan-Yuan
    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;希爾伯特-黃轉換;;時頻分析;降雨特性;Laonong river basin;HHT;Entropy;time frequency;rainfall characteristics
    Date: 2012
    Issue Date: 2013-04-13 12:04:22 (UTC+8)
    Abstract: 台灣是個位於亞熱帶地區的海島國家,約有三分之二以上的面積屬於丘陵及高山地,地形變化起伏大,降雨的時間及空間分布上極不均勻。為了解降雨時空分布之非線性及非穩態等特性,本研究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)來進行時頻分析。有別於一般HHT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降雨特性探討,展現了探究水文時頻特性之另一可行途徑。
    Taiwan is an island located in the subtropical regions with more than about two-thirds of the area belonging to the hills and mountains. Because of the terrain, the temporal and spatial distribution of rainfall is very uneven. In order to explore the characteristics of rainfall with non-linear and non-stationary nature, a relatively new method of Hilbert-Huang transform (HHT) will be used to carry out the time-frequency analysis in this study. Traditionally, the HHT spectrogram is explained with the eyes. To improve the problems, the entropy that can measure the signal uncertainty will be utilized to quantify the time-frequency signal characteristics of rainfall. The combined HHT-entropy method is used to investigate the rainfall characteristics of the Laonong River Basin in the southern Taiwan in this study following.

    The results show that the entropy is indeed a good indicator to quantify the time-frequency energy distribution with concentrated or dispersive trend. In the analysis of rainfall parameter for long-time scale, the rainfall data from 1992 to 2009 in the stations of Laonong River Basin are analyzed. It is shown that the year cumulative rainfall, annual average rainfall intensity, and the 1-day, 2-day, and 3-day annual maximum rainfall, etc., are obviously with rising trend for the majority of stations. Because larger maximum daily rainfall makes the year-round rainfall more concentrated, the associated entropy of rainfall is lower. It should be paying more attention to the meteorological event that is short duration with heavy intensity to reduce the possible disaster. On the other hand, in the analysis of rainfall parameter for short-time scale, four typhoon events, including the 1996 Herb, 2004 Mindulle, 2008 Sinlaku, and 2009 Morakot, etc. are evaluated. According to the analysis results, it shows that the relationship between entropy and cumulative rainfall and the average rainfall intensity is less obvious, but with positive correlation for typhoon duration. It means that the longer the typhoon duration, the wider the range of the energy distribution of the typhoon event with heavy intensity, and the greater the likelihood of hazard may occur. Thus, more attention should be paid to typhoon events with long rainfall duration and heavy rainfall intensity that may bring damage in the future.
    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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