海堤設計暴潮位之風險率分析

本文由承擔風險率之觀點，探討在某一使用年限內，構築海堤時所應該採用之暴潮位，並且以臺灣西部海岸之芳苑及塭港兩潮位站爲例，說明承擔風險率、海堤設計年限及設計暴潮位三者之間的關係。由於芳苑及塭港兩潮位站之記錄年限均未超過25年，因此在潮位發生機率推算上本文採用年極端值數列，颱風期複合潮部份延時數列及颱風期氣象潮部份延時數列等三種方法相互比較。由分析結果得知，若採用年極端值數列，則芳苑及塭港兩地目前之海堤設計暴潮位均具足够可靠度；但若採用颱風期複合潮部份延時數列，則在50年安全設計年限內，此兩地分别需承擔68.7%及5.1%之失敗風險率，顯示採用颱風期複合潮部份延時數列所得到之推測潮位較傳統之年極端值數列所得到之結果保守。

關鍵字

暴潮；風險率分析；部份延時數列

並列摘要

This study discussed the risk of designed tidal level of sea wall under a given duration, and it was completed with records of Fang-Yuan and Wen-Kang tide gages, both locate at west Taiwan coast, then the relationships among risk, using duration and designed tidal level were also displayed. Because record length is less than 25 years both for Fang-Yuan and Wen-Kang tide gages, this study adopted three different models to predict tidal probability, namely extremely annual series, storm surge partial duration series and surge residual partial duration series. From the computational results, it was found that the present dike elevations have high reliabilities if extremely annual series model was taken into account, but failling probabilities will grow to 68.7% for Fang-Yuan area and 5.1% for Wen-Kang area if storm surge partial duration series model was used. Therefore, conservative results will be got as storm surge partial duration series model being used better than tradional extremely annual series model.

並列關鍵字

Storm surge ； Risk analysis ； Partial duration series

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