Long-Term Shoreline Change Analysis using Optical Satellite Images of the East Coast of the Korean Peninsula

Optical satellite images are a valuable alternative to conventional surveys by enabling consistent, high-resolution observations spanning more than 40 years. This study presents a comprehensive framework based on optical satellite imagery and CoastSat for analyzing the long-term shoreline changes on the East Coast of the Korean Peninsula, a region increasingly affected by sea-level rise, intensified storms, and human interventions. These pressures have accelerated erosion and destabilized the shoreline dynamics, posing risks to infrastructure and ecosystems. A monthly time series dataset (1984–present) was constructed using the Google Earth Engine with standardized preprocessing, including image enhancement and georeferencing. Shorelines were extracted using CoastSat, an open-source software that automates shoreline detection from multi-source satellite imagery. Nevertheless, the process required manual verification and showed reduced accuracy in anthropogenic coastal environments. Time-series analyses at Gangneung Port–Yeomjeon Beach and Gungchon–Chogok Port, where sequential coastal structures have significantly altered the shoreline dynamics, revealed distinct shoreline seasonality and horizontal shifts. These spatial patterns are closely associated with the construction of breakwaters, groins, and other structures as erosion mitigation strategies. These findings highlight the potential of long-term satellite datasets to enhance shoreline monitoring and improve coastal resilience under growing environmental uncertainties. The framework offers a scalable solution for satellite-based coastal management across evolving global environments.