應用CLIGEN氣候生成模式模擬台灣北部地區 有效降雨事件及其驗證

Abstract

CLIGEN氣候生成模式可利用連續日之氣象資料，合成產生出與降雨相關之參數，可用以輸入評估土壤沖蝕之模式，如WEPP模式、RUSLE公式等。由於整套模式在美國發展至成熟階段，對於其他地區之適用性尚屬未知，因此本研究針對台灣北部地區土壤沖蝕有效降雨事件，利用CLIGEN模式進行模擬，將其結果與1961年至1990年的歷史資料進行比對。驗證之參數分別為，年平均降雨量、月降雨分布、降雨強度、標準偏差、降雨事件機率及降雨沖蝕指數等。結果顯示在降雨量、降雨月分布及降雨事件機率上模擬結果良好，但在標準偏差、降雨強度及降雨沖蝕指數部分，有偏低之現象；由於CLIGEN模式建構於大陸性氣候的氣象資料庫之上，其模擬結果以低中強度降雨居多，而台灣地區屬海島型季風氣候，常受隨颱風而來之高強度暴雨影響，因此造成此一誤差現象之發生。

Using the climate generator model of CLIGEN, continuous daily climate data can be used to generate the parameters related to rainfall. These parameters can be used in the equations for evaluating soil erosion, such as the WEPP and the RUSLE models. The CLIGEN model has been developed to a mature stage in the continent of the United States; however, the adaptability of the model in the other areas is still unknown. Therefore, in this study, the effective rainfall events for soil erosion in northern Taiwan were simulated and compared with the historic data from 1961 to 1990. Parameters verified in this study were annual mean rainfall amount, monthly rainfall distribution, rainfall intensity, standard deviation, probability of rainfall event and rainfall erosivity. The results showed that the simulations of rainfall amount, monthly rainfall distribution and the probability of rainfall were good; however, standard deviation, rainfall intensity and rainfall erosivity were underestimated. The reasons for this may be because the CLIGEN model was established by using the continental climate data, which mainly consisted of the rainfalls with medium and low intensity. However, the Taiwan island is in a monsoon area, accordingly, the rainfall intensities are frequently very high because of typhoons.