颱風具降雨延時長且降雨強度高之特性，促使山區敏感地帶發生複合式災 害，且各災害間可能具連鎖特性，較難以預知災害規模或災;魔發生，進而使山區 聚落與鄰近河道設施受到無法預期的洪澇災害衝撃。目前危害評估研究缺乏整合 性，為此本研究將針對莫拉克颱風事件下之南沙魯里進行複合式災害之危害評 估。首先透過災害數值模擬軟體分析土石流危害與堆積範圍（FLO-2D)，並再對 旗山溪南沙魯里河段進行洪澇危害評估（HEC-RAS)，而為證實土石流對洪澇危 害的複合式災害（Compound Disaster)特性（鏈結與累加性），洪澇模擬分為正常 洪水情境與複合式災害情境，以探討兩情境評估結果之差異。土石流評估上對 DF007與DF070進行模擬，結果發現旗山溪受土方量堆積使得河道地形大幅抬 升。兩情境洪澇模擬上，複合式災害情境之河道地形受土石流堆積土方量擠壓， 使河道主槽靠往右岸且通洪斷面減少而發生回水效應，故此情境之流動範圍、最 大流動深度與平均流動深度皆高於正常洪水情境（分別為66.4%、57%、35%)。 最後利用災後地形高程模型、災後影像與實際災情檢核進行驗證，發現複合式災 害模擬情境結果於各驗證項目上皆較為準確。故於山區地帶上，強降雨事件之洪 澇危害評估需考量土石流扇狀地堆積物的影響，才能使災前危害評估與防災規劃 更為完善。

Typhoon rainfall induces multiple hazards in mountain villages. These hazards have a cascade effect, causing government and public to incompletely foresee and manage the disaster risk. Many studies have not comprehensively identified disaster hazards due to lack of understanding of the Compound Disaster perspective. Therefore, this study adopts these concepts to hazard assessment in Nansalu. The disaster categories of assessment include debris flow and flood. The potential hazard region of the debris flow and flood are computed separately using FLO-2D and HEC-RAS, which are numerical simulation modeling software packages. Results of debris flow analysis demonstrate that the topography of the Cishan River changed because of sediment-deposit. In flood analysis, in order to understand the cascade effect of Compound Disaster, this study designs two simulation scenarios to compare the assessment results in each. These scenarios are the “Normal Flood Assessment” scenario and “Compound Disaster Assessment” scenario, which considered the simulation terrain to have been deposited by debris flow. Simulation results show that the flow direction of Cishan River was changed (from left bank to right bank), and in the “Compound Disaster Assessment” scenario results, the flow area, maximum flow depth and average flow depth was 66.4%, 57% and 35%, respectively, higher than the “Normal Flood Assessment” scenario results owing to the backwater effect. Finally, the digital elevation model, the disaster image and the disaster information are utilized to validate the result of hazard assessment. This study concludes that the result of validation analysis from the “Compound Disaster Assessment” scenario are more similar to reality than those from the “Normal Flood Assessment” scenario in, especially in terms of the reality disaster information. In conclusion, disaster assessment analysis should define the potential hazard area using the Compound Disaster perspective, particularly in mountain communities. Therefore, disaster prevention planning is the best option for avoiding losses from disasters.