近年來，台灣地區氣候變動異常，降雨量極端不穩定，此種雨量之改變可能導致仰賴水庫蓄水的台灣地區因氣候異常變動而造成降雨量不足之乾旱現象。
本文收集台灣地區26個近百年雨量測站之長期雨量紀錄，並對少部份具有缺漏測站進行資料補遺，以利後續分析長期氣象乾旱變動趨勢之完整性。首先建立台灣地區各雨量站之標準化降雨指標(Standardized Precipitation Index, SPI)，分析長期SPI序列變動特性，並使用Cumulative Deviations檢定法，探討台灣地區各雨量站之改變點前後是否存在顯著差異。進一步探討改變點前後之氣象乾旱特性變異，並建立不同乾旱特性之乾旱頻率分析，以探討長期之氣象乾旱特性趨勢。
本研究演算長期SPI序列變動之改變點，發現北部地區各站之改變點大約在1960~1970年代左右，中、南部地區各站之改變點大約在1950~1960年代左右，東部地區因只有兩個長期雨量測站，較無區域之代表性。在各乾旱特性(乾旱年平均發生次數、乾旱延時、乾旱嚴重度(Drought Severity)及乾旱強度(Drought intensity))變動趨勢方面：北部地區在改變點後之氣象乾旱特性為稍微減弱趨勢，而中、南部地區在改變點後卻為增強趨勢。進一步由不同乾旱特性之機率分佈特性，發現乾旱延時符合指數分佈，乾旱嚴重度及乾旱強度符合Gamma分佈，再根據不同乾旱特性之機率分佈所建立的重現期可知：台灣中、南部地區在改變點後之氣象乾旱特性發生機率已漸趨增加，且南部地區之增加趨勢較中部地區明顯。

Abnormal climate and dramatic change of rainfall happen recently in Taiwan. The variations of rainfall could lead to more frequent drought in Taiwan where depends on storage water of reservoirs.
The study collected around 100-year rainfall records from 26 rainfall stations and reconstructs the missing monthly rainfall data by single and multiple regressions resort to records in neighbour raingauges in order to analyze the variations and tendency of the long-term meteorological drought. First of all, the Standardized Precipitation Index (SPI) was calculated. Cumulative Deviations test was adopted to investigate the change point of every station and to check if any remarkable differences existed before and after the change points. Moreover, this study investigated the variations of the meteorological drought before and after the change points and determined drought frequency analyses for three drought variables.
This study found that the change points in northern Taiwan were in 1960-1970. In central and southern Taiwan, the change points were in 1950-1960. Two raingauges with long-term rainfall records in eastern Taiwan do not have consistence change points. From the study on four drought properties (the average of yearly drought occurrence, drought duration, drought severity and drought intensity), the meteorological drought in northern Taiwan is weaker after the change point, and is stronger in the later periods in central and southern Taiwan. The study further found from the probability analyses that the drought duration can be fitted by Exponential distribution, and the drought severity and the drought intensity are fitted by Gamma distribution. According to the drought frequency analyses, the occurrence probabilities of meteorological drought are increased after change points in central and southern Taiwan; however, the increasing tendency in southern Taiwan is more obviously than in central Taiwan.

1. 中央氣象局，「專用氣象觀測站基本資料」，1990。
2. 中央氣象局，「專用氣象觀測站基本資料」，2000。
3. 吳宗正，「現代統計學」，偉哲書局，台南市，1985。
4. 呂季蓉，「台灣南部地區長期乾旱趨勢分析之研究」，國立成功大學水利及海洋工程研究所碩士論文，2006。
5. 吳宗正，「現代統計學」，偉哲書局，台南市，1985。
6. 宋嘉文，「氣候變遷對台灣西半部地區降雨及乾旱影響之研究」，國立成功大學水利及海洋工程研究所碩士論文，2003。
7. 徐享崑，「水資源永續發展導論」，經濟部水資源局，2000。
8. 張炎銘，「建立乾旱警報系統初論」，台灣水利，第39卷，第4期，第73-83頁，1991。
9. 許晃雄，「坦然面對氣候變遷」，科學月刊，第31卷，第五期，2003。
10. 黃文政、賴怡君，「台灣地區降雨乾旱分布之研究」，第十五屆水利工程研討會論文集下冊，S31-S36頁，2006。
11. 經濟部水利署，「中華民國九十三年台灣水文年報」，2004。
12. 經濟部水利署，「環境情勢分析與優先法展課題」，94~97中程施政計畫，2005。
13. 經濟部水資源統一規劃委員會，「台灣地區水文站況表冊」，1987。
14. 經濟部水資源統一規劃委員會，「台灣乾旱特性之研究」，1992。
15. 顏月珠，實用無母數統計方法，陳昭明發行，臺北市，1986。
16. Abramowitz, M. and Stegun, A., “Handbook of mathematical formulas, graphs and mathematical tables”, Dover Publications Inc., New York, 1965.
17. Bonaccorso, B., I. Bordi, A. Cancelliere, G. Rossi and Sutera, A., “Spatial variability of drought: an analysis of the SPI in Sicily”, Water Resources Management, 17, pp.273-296, 2003.
18. Buishand, T. A., “Some methods for testing the homogeneity of rainfall records”, Journal of Hydrology, 58, pp. 11-27, 1982.
19. Bussay, A., C. Szinell and Szentimery, T., “Investigation and measurements of droughts in Hungary”, Hungarian Meteorological Service, Budapest, 1999.
20. F. Kemal SÖnmez, Ali Ümran KÖmÜscÜ, Ayhan Erkan and Ertan Turgu, “ An Analysis of spatial and temporal dimension of drought vulnerability in Turkey using the standard precipitation index ”, Natural Hazards 35, pp.243-264, 2005.
21. Gan, T. Y., “Reducing vulnerability of water resources of Canadian Prairies to potential droughts and possible climate warming”, Water Resources Management, 14(2), pp.111-135, 2000.
22. Hann, C. T., “Statistical Methods in Hydrology”, Iowa State University Press., 1977.
23. Hollander, M. and Wolf, D. A., “Nonparametric Statistical Methods”, second condition, 1999.
24. Intergovernmental Panel on Climate Change, Climate Change 2007: The Physical Science Basis, Available from http://www.ipcc.ch/, 2007.
25. Kendall, D. R. and Dracup, J, A., “On the generation of drought events using an alternating renewal-reward model”, Stochastic Hydrology and Hydraulics 6(1), pp.55-68, 1992.
26. Lloyd-Hughes, B. and Saunders, M. A., “A drought climatology for Europe”, Int. J. Climatol., 22, pp.1571–1592, 2002.
27. Loukas, A. andVasiliades, L., “Probabilistic analysis of drought spatiotemporal characteristics in Thessaly region, Greece”, Natural Hazards and Earth System Sciences, 4, pp.719-731, 2004.
28. Mathier, L., Perreault, L., Bobe, B., “Stochastic renewal model of low-flow streamflow seruences”, Stochastic Hydrology and Hydraulics 10(1), pp.65-85, 1992.
29. Mathieu R. and Yves R., “Intensity and spatial extent of drought in southern Africa” Geophysical Research Letters, vol.32, L15702, 2005.
30. McKee, T. B., Doesken, N. J. and Kleist, J., “The relationship of drought frequency and duration to time scales. Preprints”, 8th Conference on Applied Climatology, January 17–22, Anaheim, California, pp.179-184, 1993.
31. Paulo A. A., Ferreira E. et al., Coelho C., Pereira L.S., ” Drought class transition analysis through Markov and Loglinear models, an approach to early warning” Agricultural Water Management 77, 56-91, 2005.
32. Rouault, M. and Richard, Y.,“Intensity and spatial extension of drought in South Africa at different time scales”, Water SA, October, 29(4), pp.489-500, 2003.
33. Saeid M., Vladimir S., and Mahnosh M., “Comparison seven meteorological indices for drought monitoring in Iran ” Int. J. Climatol., 26, pp.1971-1985, 2006
34. Shiau, J. T. and Shen H. W., ”Recurrence Analysis of Hydrologic Drought of Differing Severity”, Journal of Water Resources Planning and Management, v.127, n.1, pp.30-40, 2001.
35. Shiau, J. T. and Shen, H. W., “Recurrence analysis of hydrologic events”, Stochastic Environmental Research and Risk Assesment ASCE 127(1), pp.30-40, 2001.
36. Shiau, J. T., “Return period of bivariate distributed extreme Hydrological Events”, Environmental Research and Risk Assessment, 17(1-2), pp.42-57, 2003.
37. Shiau, J. T., “Fitting drought duration and severity with Two-Dimensional Copulas”, Water Resources Management 20, pp.795-815, 2006.
38. Sims, A. P., Niyogi, D. D. S. and Raman, S. “Adopting drought indices for estimating soil moisture: A North Carolina case study”, Geophysical Research Letters, 29, art. no. 1183, 2002.
39. Sirdas, S. and Sen, Z. “Spatio-temporal drought analysis in the Trakya region, Turkey” Hydrological Sciences-Journal-des Hydrologiques, 48(5) Oct.2003
40. Szalai, S. and Szinell, C. “Comparison of two drought indices for drought monitoring in Hungary—a case study”, In: J. V. Vogt, F. Somma (eds), Drought and drought mitigation in Europe, Kluwer Academic Publishers, Dordrecht, pp.161–166, 2000.
41. Vicente-Serrano, S. M. and Lopez-Moreno, J. I., “Hydrological response to different time scales of climatological drought：an evaluation of the standardized precipitation index in a mountainous Mediterranean basin”, Hydrology and Earth System Sciences Discussions, 2, pp.1221-1246, 2005.
42. Zelenhastic, E. and Salvai, A., “A method of streamflow drought analysis”, Water Resources Research 23(1), pp.156-168, 1987.