Coastal geomorphologic change detection using SAR and optical remote sensing data at the Nakdong River Estuary, Korea

Coastal geomorphology in the Nakdong River Delta, South Korea, has conspicuously changed partly by human activities and partly by natural processes. In this study, we discuss the characteristics of SAR data over the coastal region and an efficient approach to detect coastal geomorphologic change in the study area. Eight data sets were collected over the study area including four SAR images. Although SAR images are very useful to detect coastal change, speckle noise in SAR images is, however, a serious problem in this application. A weighted averaging process of multiple SAR data sets in the wavelet domain effectively reduces the speckle in the RADARSAT SAR fine beam mode image. The speckle reduced SAR image is then combined with optical data such as Landsat TM or MSS to evaluate the morphologic changes in the coastal region. The straight comparison of optical and SAR data is not efficient mainly because of differences in resolution. Instead of that, optical and SAR data fusion through the Brovey transform enhances the geomorphologic changes in the coastal area. Through the approach, we have successfully delineated the geomorphologic changes made by natural processes and human activities over the study area. In short, the SAR data acquired in different resolutions and incidence angles are very promising to monitor geomorphologic changes in coastal regions when they are combined with optical remote sensing data.