Spatiotemporal Analysis of Shoreline Changes in Mobile Bay, U.S.A

Abstract Shoreline changes affect coastal communities by altering ecosystems and storm buffers. With the growth of coastal populations, the societal impact of shoreline change is expected to increase. Understanding the past and present shoreline positions is thus essential for managing coastal hazards and supporting population as well as ecosystem services. This study quantifies shoreline change rates and evaluates the persistence and variability of shoreline behavior in Mobile Bay, U.S., over the past 25 years (2000–2024 inclusive). CoastSat, an open-source Python software toolkit built on the cloud computing platform Google Earth Engine (GEE), is used to detect shoreline positions and analyze change rates. Furthermore, the Hurst exponent analysis is applied to the shoreline change rate of 396 shore-normal transects to assess the persistence or randomness of shoreline change behavior. The findings reveal substantial spatial heterogeneity in shoreline dynamics across Mobile Bay, with Dauphin Island exhibiting the highest erosion rate (5.4 m/yr), the greatest shoreline variability between the northern and southern shore, and the strongest responses to major hurricane events. In contrast, the more sheltered estuarine shorelines towards the riverine delta experienced smaller shoreline displacements and more localized variability. The integration of persistence analysis with conventional erosion–accretion assessments enabled the distinction between persistently erosional, persistently accretional, and highly variable shoreline segments, providing additional insight into long-term and short-term shoreline behavior. The findings contribute to a more comprehensive understanding of shoreline dynamics and support site-specific coastal management, hazard mitigation, and the implementation of nature-based solutions.