臺灣南部水庫集水區受極端降雨衍生複合型土砂災害之調查分析

Investigation on the Compound Sediment Disaster Induced by Extreme Heavy Rainfall occurred at Southern Taiwan

蔡光榮(Kuang-Jung Tsai) ； 李明熹(Ming-Hsi Lee) ； 陳怡睿(Yie-Ruey Chen)

《臺灣鑛業》 70卷4期 (2018/12) Pp. 29-38

摘要

2009年8月的莫拉克（Morakot）颱風侵襲臺灣帶來驚人雨量，南臺灣之嘉義縣、臺南市、高雄市及屏東縣等轄內山區累積連續3天最大降雨量高達2,900公厘以上，幾乎占臺灣全年平均降雨量之85%，造成嚴重山崩與土石流等複合型土砂災害。依據水土保持局之衛星影像判釋分析顯示，莫拉克重災區高屏溪流域即有多達1萬904處崩塌與多處堰塞湖形成，總崩塌面積高達1萬8,113公頃。有鑑於此，本研究期能以GPS/GIS/RS科技整合技術，應用於曾文與南化等二水庫集水區內坡地複合型土砂災害區之野外調查和受災區域之災情資訊蒐集分析，俾期能掌握曾文與南化二水庫集水區內相關坡地致災因素、致災區域範圍與曾文與烏山頭二水庫集水區內之複合型土砂災害調查分析，同時蒐集至少近10年來之極端降雨事件，據以探討在極端氣候變遷下之二水庫集水區土砂災害發生機制、災害風險認知及大規模崩塌後之複合型土砂災害運移行為綜合性調查分析，最後提出二水庫集水區之經營治理方案與坡地保育利用策略，以期未來可作為曾文與南化二水庫集水區與臺南／高雄二大都會區之防救災體系研擬檢討之參考依據。

關鍵字

極端降雨 ； 複合型土砂災害 ； 集水區經營

並列摘要

Extremely rainfall amount were brought by Morakot typhoon in August, 2009. The accumulated rainfall amount was more than 2,900mm within continuous 3 days that were occurred at Chiayi, Tainan, Kaohsiung and Pingtung Counties. Almost 85% of annual rainfall was precipitated in this island. Very serious landslide, debris flows, flooding and sediment related disasters were induced by this particularly heavy rainfall event. According to the satellite image analysis project was conducted by Soil and Water Conservation Bureau after Morakot event. This result indicated that more than 10,904 sites of landslide with total sliding area of 18,113ha were found by this project. All severe sediment related disaster areas are 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 and Wusanto Reservoir Watershed located at the southwestern Taiwan become the most serious compound disaster areas. In order to decrease the risk of compound disasters on both slope land and forestry land, the strategy of slope land conservation indicated that land stabilization, hazard mitigation system and sediment related disaster prevention should be executed as soon as possible. Meanwhile, study on the mechanism and behavior of large scale compounded disasters induced by heavy rainfall become an important issue which was seriously concerned by the government in Taiwan. Hopefully, all results come from this integrated research project can be used as a reference for the disaster prevention systems operated by Tainan-Kaohsung city government in Taiwan.

並列關鍵字

Extreme rainfall ； Compound disasters ； Watershed Management