ASSESSING THE APPLICABILITY AND ERROR FACTORS OF THE SHORELINE MONITORING SYSTEM BASED ON SATELLITE SAR IMAGES

Abstract

 Shoreline extraction from satellite synthetic aperture radar (SAR) images (L-band) was examined for 18 coasts. The success rates of the extraction and the accuracies of the extracted shoreline positions were evaluated, and the applicability of the method was assessed. The success rate and accuracy varied among images acquired for the same coast. Shoreline extraction was not successful when the off-nadir angle of observation exceeded 40 degrees. The accuracy of estimated shoreline position was higher for coarsegrained coast than for coast with fine sand. The estimated shoreline positions tended to be shifted 0-20 m in the landward direction from the true shoreline, and the position sometimes reached the front edge of the vegetation zone. No remarkable improvement was observed when X-band SAR images were used for shoreline extraction on five coasts, suggesting that wave-length may not affect the accuracy of shoreline positioning. These findings will provide some guidance for selecting satellite SAR images and target coasts and will contribute to further development of the shoreline monitoring system.