氣候變遷對臺灣年降雨沖蝕指數潛在影響

Potential Influence of Climate Change on Annual Rainfall Erosivity Factor in Taiwan

江介倫(Jie-Lun Chiang)

《地理學報》 68期 (2013/04) Pp. 1-17

https://doi.org/10.6161/jgs.2013.68.01

摘要

臺灣位於熱帶與亞熱帶區，多颱風與地震，山高水急加上降雨時空分佈特性導致土壤沖蝕嚴重。而通用土壤流失公式（USLE）為目前世界上應用最廣泛的土壤流失估算模式，亦是我國政府部門及水土保持技術規範所採用的土壤沖蝕估算公式。其中降雨沖蝕指數在臺灣已有前人研究成果可供參考，唯近年來氣候變遷趨勢日益嚴重，其導致的降雨變化將直接影響土壤沖蝕之估算，因此本研究修訂氣候變遷下之降雨沖蝕指數R。由於現今氣候變遷之模擬仍以長期之變化趨勢為主，而非短期及極端事件之模擬，故本研究以國際政府間氣候變遷觀察小組（IPCC）公告A2、B2情境下的大氣環流模式（GCMs）模擬之未來降雨趨勢，配合雨量站之年降雨量與土壤沖蝕指數間關係，進而探討未來短、中、長期之降雨沖蝕指數R之變化，發現雖然各模式模擬結果不盡相同。但大部分模式模擬之年降雨沖蝕指數在未來較基期高，大致依未來短、中、長期而升高趨勢越明顯，且南部之降雨指數增加幅度大於中北部，而各模式間的變異隨著時間（未來短期、中期、長期）變異越來越大。最後以地理統計之克利金法（Kriging）推估臺灣地區之降雨沖蝕指數圖，以供未來規劃長期集水區治理及推估土壤流失量時利用。

關鍵字

通用土壤流失公式 ； 土壤沖蝕 ； 克利金 ； 年降雨量

並列摘要

Taiwan is situated in the tropical and subtropical region with frequent typhoons and earthquakes. The characteristics of the non-uniform spatial and temporal distribution and the steep terrain make soil erosion a serious environmental issue in Taiwan. The Universal Soil Loss Equation (USLE) is a commonly used formula to estimate soil erosion. In this study, Rainfall erosivity index (R) was re-evaluated because climate change has influenced rainfall distribution and seriously affected the estimate of soil erosion. Nowadays, climate change simulation is used to evaluate long-term trend, but not for extreme event. As a result, this study discussed erosivity index (R) in the short-term, mid-term and long-term periods in the future. This study discussed and compared two climate scenarios (SRES-A2, B2) rainfall data which were obtained by various GCMs (CCSRNIES, CGCM2, EH4, GFDL and HADCM3) released by Intergovernmental Panel on Climate Change (IPCC). Rainfall erosivity index (R) of climate scenarios was re-evaluated from annual rainfall derived from GCMs by the relation between annual rainfall and R. The rainfall erosivity indices of short-term, medium-term and long term periods in the future were gained individually. Results showed that R increased in the future; the increase of R in southern Taiwan is larger than that of other place. Variation of R based on various GCMs is larger along the time period. The erodent map of Taiwan was obtained using Kriging estimation, which can be utilized for long-term watershed management and the estimation of soil loss.

並列關鍵字

Universal Soil Loss Equation (USLE) ； soil erosion ； Kriging, annual rainfall

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