台灣面臨多項天然災害的威脅,尤以颱風所帶來的洪水及土石流最為嚴重,導致越來越多的民眾因此遭受生命財產的危害與損失。於是,如何有效地降低損害,即是防救災的重要課題。而脆弱度可視為在特定環境災害條件下,產生傷亡與財產損失的可能性。過去的評估其實忽略了當地社會特質與其他因素的交互作用,這些未被納入考量的因素,可能會影響到災害發生時的損失程度。本研究選定大甲溪流域為範圍,並以颱風洪水、土石流災害為前提,架構出合適的脆弱度評估體系與指標。並應用分析網路程序法來處理相互影響的因素,以求得各個評估指標之權重,藉此發掘何處潛在損失會比較嚴重。 結果顯示,高脆弱度地區主要集中在流域中上游的和平鄉,往下的東勢鎮與新社鄉絕大部分亦是,另外石岡鄉和外埔鄉也有少數的村里呈現高脆弱度。在沿海的大甲鎮、大安鄉、清水鎮與外埔鄉則是低脆弱度。 本研究認為,首先,高脆弱度地區之開發猶如雙面刃,在相關的政策上,必須慎重考量其執行的優先順序。第二,低脆弱度的鄉鎮若能維持穩定的現況,適度發展應是允許的。第三,空間系統下的脆弱度得分,雖然圖形呈現隨機分布形態,但若從各個面去探討,仍可針對不同的原因給予不同的對策。最後,都市發展用地因為相對面積過小,若僅改變部份的用地形態,對於降低脆弱度的影響程度其實是微乎其微。
Taiwan has faced many threats from natural disasters, especially floods and debris flows. They cause more and more lives and properties suffered the harm and loss. Thus, it is an important issue for disaster management that how to decrease damage effectively. Vulnerability can be considered in specific conditions of environmental disasters, resulting in casualties and the possibility of damage to property. However, traditional researches neglected interactive between social characteristics and other factors which could influence the degree of losses. The purpose of this study is to framework the vulnerability model and assessment indices in Ta-Chia river basin, and the disasters focus on floods and debris flows. We apply Analytic Network Process (ANP) to deal with the interactive factors to evaluate weight of assessment indices. The results of this study depict the vulnerability map in Ta-Chia river basin to figure out where the potential loss will be serious. Through the analysis, Heping (和平鄉), Dongshih (東勢鎮), Shinshe (新社鄉), Shrgang (石岡鄉) are high vulnerability villages where allocate on upper and middle of Ta-Chia river basin. In addition, Dajia (大甲鎮), Daan (大安鄉), Ching-Shui (清水鎮) and Waipu (外埔鄉) are low vulnerability villages where allocate on lower of river basin. In this article, first, it is a dilemma issue to develop on high vulnerability areas. We must consider the implementation of prioritues carefully in related policies. Second, if low vulnerability towns keep current status stably that should be moderate develop. Third, although the vulnerability pattern of social-ecogical system is random distribution, we could give different strategies from different aspects. Finally, it is limited if we regulate part of urban development lands to reduce the degree of vulnerability, because the areas are much less than order form of lands.