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 been conspicuously changed in the last two decades partly by human activities and partly by natural processes. In this study, we discuss the characteristics of SAR data over 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 image is very useful to detect coastal change, speckle noise in SAR image is, however, a serious problem in this application. An weighted averaging process of multiple SAR data sets in 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 difference in resolution. In stead of that, optical and SAR data fusion through Brovey transform enhances the geomorphologic changes in the coastal area. Through the approach, we have successfully delineate the geomorphologic changes made by natural processes and human activities over the study area. In short, the SAR data acquired in different resolution and incidence angle are very promising to monitor geomorphologic changes in coastal region when it is combined with optical remote sensing data.