Analysis of Synthetic Aperture Radar (SAR) data from satellite imagery has become preferable by enhancement of its technology, reliable temporal and spatial resolution, computational power and extensive area of coverage. This paper presents the use of SAR data to map the extent of the inundated area of the river as the primary access way in Banyuasin Regency for water transportation. In this study, 1-year data set of Ground Range Detected (GRD) type radar data from Sentinel-1A’s mission was used and analysed by using the Science Toolbox Exploitation Platform (SNAP) toolbox. Related factors on a diurnal tide of river water level and climate which controls the inundated area located mostly within lowland and the biannual season were taken into consideration in the selection of the data set. It is found that the extended inundated area of water body clearly detected. The enhanced polarisation index (VHdB*) which was developed have given a better insight for a response on the extent of inundated area and siltation caused by erosion and sedimentation.