極端降雨影響曾文水庫集水區大規模崩塌土砂量之變異分析

A Study on the Sediment Quanity Variation of Large Scale Landslides Induced by Extremely Heavy Rainfall Occurred at Zengwen Watershed in Southern Taiwan

蔡光榮(K.J. Tsai) ； 李明熹(Y.S. Hsu) ； 陳怡睿(Y.R. Chen) ； 陳筱妍(X.Y. Chen)

《鑛冶：中國鑛冶工程學會會刊》 61卷3期 (2017/09) Pp. 8-24

https://doi.org/10.30069/MM.201709_61(3).0001

摘要

2009年8月8~9日莫拉克(Mo-rakot)颱風侵襲台灣挾帶極端強降雨量，促使嘉義縣、高雄市及屏東縣等轄內山區連續累積三天之最大降雨量高達2,900公厘以上，幾乎佔台灣全年平均降雨量之85%，而南投、臺南及屏東等地區之最大三天累積降雨量亦超過1,500公厘，因而造成嚴重山崩、土石流、堰塞湖、洪患與土砂災害。依據農委會水土保持局(2010)與成大防災中心(2010)之福衛二號(Formosat II)衛星影像判釋分析顯示，屬莫拉克重災區之高屏溪流域即有多達10,904處崩塌，總崩塌面積高達18,113公頃。有鑑於此，本研究計畫，遂以GPS/GIS/RS科技整合技術應用於曾文水庫集水區內大規模崩塌土砂災害區之野外調查和受災區相關災情資訊之蒐集分析，俾期能掌握曾水庫集水區內坡地大規模崩塌之致災因素與其土砂運移行為分析探討，甚至對其致災區域範圍之判釋，俾期降低崩塌土砂災害致災風險。因此如何考量南台灣因受全球氣候變遷衍生極端降雨之衝擊影響下，進行大規模崩塌土砂災害發生機制探討與曾文水庫集水區內之崩塌土砂生產量變異分析，終至提出集水區土砂災害治理策略，延續水庫蓄水壽命，確保水庫整體治理，進而確保國土永續利用目標，乃為本研究之重要課題。

關鍵字

氣候變遷 ； 極端降雨 ； 土砂災害 ； 集水區經營

並列摘要

Within 3 days in August 2009, Morakot typhoon brought in more than 2,900 mm of accumulated rainfall in Tainan, Kaohsiung and Pingtung Counties. It was equivalent to 85% of normal Taiwan annual precipitation. The heavy rainfall caused disasterous landslides, rushing debris flow and enoumous sediment deposits. After Morakot event, the Soil and Water Conservation Bureau conducted the satellite image analysis. The purpose of this research mainly focused on applying field investigations assisted with GPS/ GIS/RS technique to investigate the characteristics and mechanism of the sediment related disasters induced by large scale landslides. Results indicated that more than 10,904 sites of landslide in a total sliding area of 18,113 ha. All severe sediment related disaster areas were also characterized based on their disaster type, scale, topography, major bedrock formations and geologic structures during the period of extremely heavy rainfall occurred at the southern Taiwan. Zengwen reservoir watershed, located at Kaohsiung, Chiayi and Pingtung counties, was also selected as a major study area. To decrease the risk of large scale landslides on slope land in Zengwen watershed, the slope land conservation and stabilization and sediment disaster prevention and mitigation programs should be implemented immediately.

並列關鍵字

Climate change ； Extremely heavy rainfall ； Sediment disasters ； Watershed management