圖書典藏及影音數位平台

在氣候變遷威脅下，海岸侵蝕可能加劇，海側之消波緩衝帶逐年縮減，海岸防護設施則可能因此造成基礎掏空而損壞，引發複合型災害，如暴潮溢淹，導致災害擴及陸域，造成更大規模的損失。目前依據海岸管理法四類海岸災害潛勢劃設之一、二級海岸防護區，其劃設方式尚未將災害潛勢引致之風險納入評估。本計畫擬針對具有海岸侵蝕及暴潮溢淹等複合型災害潛勢之一級海岸防護區，建立海岸地形變遷對海岸防護設施之影響評估方法，進而以風險分析理念，將災害潛勢與社會經濟層面整合以評估海岸侵蝕災害風險，並建置風險地圖，再依據風險程度擬定海岸防護之非工程管理對策，以降低海岸災害風險，達到海岸永續經營之目標。

To maintain natural systems, ensure zero loss of the natural coast, respond to climate change, prevent coastal disasters and damage to the environment, protect and restore coastal resources, implement integrated coastal zone management, and promote the sustainable development of coastal zones. The ministry of the interior (MOI) respectively declared The Coastal Management Act and the Integrated Coastal Zone Management Plan in 2015 and 2017, regarding coastal erosion as one of the coastal statutory disasters, designating the first-class and second-class coastal protection zones by the disaster potential. There are two considerations and motivations in this project. Firstly, if the coastal erosion keeps occourring, it might brush the foundation of coastal defense and induce the unstable coastal defense broken down when the typhoon invades Taiwan. Therefore; the villages behind the defense would suffer the inundation of storm surge, upgrade the damage probability of the villages drastically. The second one is the scale of first or second-class coastal protection zones which designate by sediment cells. In other words, the coastal protection zone was not only defined by the large-scale but classified to the same class that couldn’t illustrate the spatial distribution of coastal hazard potential precisely. Further, the coastal sectors of the protection zone were based on the hazard potential not included the damage of social-economic which induced by them. Therefore, for the goal to protect national resources and evaluate the risk of coastal erosion holistically. This project proposed the principles and methods with down-scales, including the influence of coastal erosion on coastal facilities, the risk assessment that consists of coastal erosion and the inundation of storm surge induced by coastal erosion. Ultimately, according to the risk map to develop the strategies of the non-engineering reduction management for coastal protection and achieve the goals of the sustainable coastal utilization. In this project, Yunlin coastal area was demonstrated this year. According to the analysis of shoreline change and the volumetric, the sectors of Xinxing tideland seawall, Taixi tideland seawall, Santiaolun seawall, and Xingkang seawall were under erosion hazard potential. Although the functionalities of them were all compliance with protective standards, the overtopping of them increased under the scenario of erosion in five years and the buffer zones of Santiaolun and Xingkang were reaching toes of themself. The scenario analysis of 50 returned period and climate change storm surge, showing the villages behind the Santiaolun and Xingkang seawall would suffer the inundation more than 2m mostly once the coastal defense broke down by coastal erosion. The risk assessment consists of hazard and vulnerability index which is formulated from the United Nations Disaster Relief Organization. The significant factors and the weights of them were calculated by the questionnaire. On the basis of scores and weights of hazard and vulnerability index, calculating the risk level by inputting the index into the risk matrix. The seven villages which were under the potential of coastal erosion, besides the Yongfeng was extremely low, the other six villages distributed low~medium risk level. Consequently, this project proposed the strategies of non-engineering management for seven villages that are under coastal erosion, including the management of seaward sand utilization; promote the warning system, the hard and soft devices for disaster prevention in the landward, etc., to achieve the purpose of disaster prevention and sustainable use of the coast.