Author(s): Wei-Po Huang; Chorng-Yeu Chiang; Chun-Jhen Ye; Jui-Chan Hsu

Linked Author(s): Wei Po Huang

Keywords: Environmental degradation zones; Coastal defenses; Sustainable use

Abstract: Coastal defenses are essential for safeguarding human lives and assets; however, their long-term maintenance often becomes unsustainable when costs outweigh protective benefits. To address this, setback lines and environmental degradation zones (EDZ) offer strategic alternatives by enabling managed retreat and restoring natural shoreline dynamics. This study develops a systematic framework to evaluate the necessity, urgency, and feasibility of designating EDZs along the Hualien coast, Taiwan, a region highly exposed to typhoon impacts and shoreline erosion. Using the Fuzzy Delphi Method (FDM), nine representative indicators were selected. An environmental degradation score was then calculated as the square root of the geometric mean of these indicators, following a normalized five-level classification. Results reveal that most coastal sectors exhibit Minor to Significant degradation, manageable through facility maintenance and adaptive measures. However, sectors categorized as Severe or Extreme degradation indicate unsustainable defense investment, where retreat and EDZ designation are necessary for rational resource allocation and sustainable coastal development. By integrating physical hazards, land-use conditions, and socio-economic feasibility, this study provides a replicable decision-support tool for evaluating the long-term viability of coastal defenses and guiding strategic retreat policies under climate change.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.115

Year: 2026