Study on Evolutions of Jiangsu Radiating Sandbanks Based on SAR Images

The main goal of this study is to obtain high-resolution data to describe the evolution trends of Jiangsu Radiating Sandbanks, which exhibit considerable quasi-regular variations. Because SAR images have the advantages of imaging underwater sandbanks and all weather, we collect different period images to analyses the temporal and spatial variability of Jiangsu Radiating Sandbanks. The result indicates that the evolutions of Jiangsu Radiating Sandbanks are both in two and three-dimension. The former is related to overall on/off shore sandbanks migration, whereas the latter is induced by the horizontal amplitude growth, migration, or length scale change of the quasi-regular topography. By using the methods of crisp enhancement, density slice, overlay analysis and supervised classification etc, we show the changes of primary sand ridges, and then conclude the evolution trends of the whole radiating sandbanks. 1. INTRODUCTION The Yellow Sea is a shallow marginal sea of the western Pacific, lying north of, and adjacent to the East China Sea. The Yellow Sea receives large amounts of sediment from Chinese rivers. The great preponderance of sediment physiognomy in the Yellow Sea is Jiangsu Radiating Sandbanks (as Fig.1). There are a series of underwater radiating sand ridges along the coast of Jiangsu. The troughs alternate with ridges and distribute about 200km from south to north and 140km from east to west where the water deep is between 0m and 25m. The radiating sandbanks have complicated and special hydrodynamics, geology and geomorphology conditions. The tidal current is strong in this area. Average speeds of flooding and ebbing of tidal current in this area are over 1.4 m/s. Average tide range in this area is about 2.5~4.0 m, and the largest tide range of Huangsha tidal channel is up to 9.28 m. Here in this study, SAR images are chosen to analysis the distributing characteristics and evolution trends of Jiangsu Radiating Sandbanks.