Integrated Vulnerability and Hazard Assessment of Shoreline Change Using LRRDS Simulation Models: A Case Study of Ghashm Island’s Coastal Morphology and Historical Shoreline Dynamics Maps

Shoreline locations are continuously altered by both natural processes and human activities, and these changes provide critical information for Coastal City Hazard Assessment (CCHA), including the evaluation of coastal erosion and accretion. Along the coast of Qeshm Island, Iran, shoreline recession driven by coastal erosion poses a persistent challenge, exacerbated by limited historical data, which introduces uncertainty into sustainable coastal development planning. In particular, the absence of established setback lines has contributed to damage to coastal structures and ecosystems. This study utilized multi-source shoreline datasets, including aerial photographs, high-resolution satellite imagery, geologic maps, and GPS survey data spanning 1956–2009. A combination of geomorphological, statistical, and cartographic methods was applied to generate segment-based shoreline change data, dynamic shoreline maps, and quantitative analyses of change rates. Results demonstrated that the selection of appropriate geomorphic indicators was strongly influenced by local and regional geomorphology. Sandy beaches exhibited the highest erosion, with an average recession rate of − 0.72 m/yr, while coastal cliffs retreated at − 0.33 m/yr, yielding an overall shoreline recession rate of − 0.51 m/yr. Approximately 40% of the shoreline was classified as experiencing high to very high recession rates. Recession rates were used to delineate beach erosion setback lines and map coastal erosion hazard zones. A novel Linear Regression Rate combined with Dynamic Segmentation (LRRDS) model was developed to predict future shoreline positions and inform setback planning. This study presents a structured, morphology-sensitive approach for assessing shoreline change, providing precise mapping, measurement, and analysis. Implementing erosion-based setback lines can assist coastal managers in mitigating vulnerabilities and supporting sustainable coastal development.