Evaluating Shoreline Prediction Models Using Satellite Imagery and Open-Source Tools

Abstract

This study integrates open-source satellite-based shoreline extraction and statistical shoreline-change analysis to evaluate tidal correction and prediction ability in two contrasting coastal settings. Shoreline change is assessed using CoastSat-derived shorelines and AMBUR (Analyzing Moving Boundary Using R)-based rate modeling at Texas, United States of America and Ishikawa, Japan. Publicly available Sentinel‑2, Landsat, and high-resolution elevation datasets (NOAA (National Oceanic and Atmospheric Administration) lidar, GSI (Geospatial Information Authority of Japan) DEM, and SDB (Satellite Derived Bathymetry)-derived bathymetry) are combined with hourly or model tide records to extract, tidally correct, and analyze multi-decadal shoreline positions. Validation at San Jose Island compares tidally corrected Sentinel‑2 shorelines with 1 m NOAA lidar shorelines in terms of baseline distance, beach slope, and shoreline elevation. The CoastSat shoreline reproduces the lidar-derived planform with a distance RMSE of 14.26 m and 80% of transects within the low‑error band; slope and elevation comparisons yield RMSE values of 3.83° and 1.05 m, with over 78% and 85% of transects, respectively, falling within corresponding low‑error thresholds. For Wajima, three different geostatistical methods were used to analyze historical Landsat shorelines from 1987 to 2014. Using 28 years of shoreline data, the 2023 pre-earthquake shoreline was extrapolated with an average error of 8.19 to 10.73 meters. The 2024 post-earthquake shoreline prediction showed errors exceeding 50 meters in MAE. Thus, when sudden shifts reshape coastlines, these trend methods fall short. Still, comparing the predicted 2023 shoreline with the observed 2024 shoreline, researchers found a coastline advance of roughly 150 to 200 meters, matching separate radar-based estimates along the Noto Peninsula. This study shows the combined CoastSat–AMBUR workflow to provides a framework for shoreline extraction, tidal correction validation, and future shoreline extrapolation and the application of CoastSat and AMBUR for before and after an earthquake.