堤防效應下之水災風險變遷與風險認知研究

Flood Risk Evolution and Risk Perception under Levee Effects

氣候變遷與都市化造成洪災風險不斷增加，各國均意識到結構式減災策略有其極限，並開始導入非結構減災措施，其中針對易淹水地區的土地利用管理被視為非結構減災的方式之一。過去的研究觀察到易淹水地區由於依賴結構式防洪策略，而未注意到都市發展的影響，導致防洪工程施作後災害風險反而增加，並稱之為「堤防效應」。堤防效應出現的關鍵在於缺乏土地利用管理，應是全球減災管理與規劃者均必須面對的課題。本研究結合堤防效應的風險分析與風險認知面向，以臺南市為研究地區進行堤防效應的探討。研究中先藉由風險變遷特徵分析探索研究地區剩餘風險變遷情形，再結合淹水災點空間型態分析指認堤防效應的潛在地區，最後藉由主觀認知的調查了解地方居民風險認知。研究結果指出，東區裕聖里及仁德區三甲里為居民具有較低的風險認知的堤防效應潛在地區，應有及早配套因應之。

Flood risk is rising nowadays due to urbanization and climate change. Traditional structural measures evidently cannot provide absolute protection from flooding, leading to increased interest in non-structural measures, especially land use management. Allowing development in flood-prone areas, relying solely on protection provided by hydraulic structures, is likely to increase flood risk over time. This paradoxical phenomenon is known as the ''levee effect'', which is caused by lack of land use control and has become a problem encountered by policy makers worldwide. This study investigates the levee effect based on both risk analysis and risk perception. First, the flood risk hazard and residual risk change before and after the Flood Prone Area Management Plan in 2006 in the study area are analyzed to identify potential levee effect areas. Questionnaire surveys are then conducted in these areas to give an understanding about the local risk perception. Analytical results reveal that Yusheng Village and Sanjia Village are potential levee effect areas, and local residents perceive a low risk, which shows the need for corresponding measures.