莫拉克颱風引致小林村堰塞湖之形成與潰決歷程

The Formation and Failure of Typhoon Morakot-Triggered Landslide Dam in Siaolin Village

陳樹群(Su-Chin Chen) ； 吳俊鋐(Chun-Hung Wu)

《中華水土保持學報》 40卷4期 (2009/12) Pp. 377-392

https://doi.org/10.29417/JCSWC.200912_40(4).0006

摘要

高雄縣小林村旁旗山溪河道在莫拉克颱風期間形成堰塞湖，本文利用莫拉克颱風期間之降雨、河川水位、獻肚山崩塌土砂量等資料，推估小林村堰塞湖之形成過程、堆積土體尺寸及潰決方式等。莫拉克颱風期間，小林村於獻肚山崩塌前之總雨量介於1218至1713mm，鄰近之甲仙及表湖雨量站降雨量都超過200年降雨頻率年估算值。旗山溪水位記錄則在2009年8月9日上午7時出現50分鐘內急降3.28m，爾後在8時30分出現1小時內急速攀升8.05m之水位，證實小林村旁旗山溪河道曾因崩塌土砂阻塞河道而出現堰塞湖。本研究利用崩塌前後地形變遷資料判釋堰塞湖堆積範圍及形狀，經估算結果：堰塞湖堆積土體長度600.0m、寬度347.8m及高度53.0m，總堆積土體體積約爲1053萬立方公尺，堰塞湖上游總漫淹面積及體積約分別爲92.3公頃及1947.5萬立方公尺。堰塞湖潰決方式則爲洪水溢流過頂(overtopping)，存在時間不到3小時，此堰塞湖屬於不穩定之堰塞湖，瞬間潰決造成嚴重傷亡事件。

關鍵字

小林村 ； 堰塞湖 ； 溢流侵蝕

並列摘要

The rainfall, water level of the Chi-Shan river, and the Mt. Xian-Du landslide volume are used to estimate the deposit area, size and dam-break progress of the landslide dam triggered by Typhoon Morakot in Siaolin Village. Typhoon Morakot brought about 30 hours of torrential rainfall with a total rainfall reaching 1218~1713 mm in Siaolin Village. The rainfall frequency at Jia-Shian station and Biao-Hu station exceeded the 200-year return period. The water level at Shan Lin Da Bridge in Chi-Shan river rapidly fell by about 3.28 m in 50 minutes and rapidly rose by about 8.05 m in 1 hour at 7 o'clock, 2009/8/9. The phenomenon also demonstrated a landslide dam occurring in the Chi-Shan river.The length, width and height of the landslide dam are 600.0, 347.8, and 53.0 m, respectively, based on geomorphological variation data. The volume of the landslide dam is about 10.5 million m^3, and the area and volume of the landslide lake were 92.3 hectares and 19.5 million m^3. The landslide dam survived less than 3 hours and collapsed due to overtopping, revealing its great instability and leading to serious casualties.

並列關鍵字

Siaolin Village ； landslide dam ； overtopping