Hai Phong Bay in Vietnam is subject to very special sedimentation patterns influenced by the Red River’s (Sông Hong) delta, the estuaries of other northern Vietnamese rivers, the tides, and monsoons. The rivers dump thousands of tons of sediments into the Bay each month, albeit primarily in the rainy season. The sediment plumes are clearly visible on the LANDSAT TM, SPOT XS and SPOT P optical satellite images shown here.

Indeed, the torrential rains that characterise the summer monsoon season lead to massive runoff down increasingly deforested slopes. The result is catastrophic erosion and watercourses with particularly high sediment loads. When the river water comes in contact with seawater in the estuary these sediments precipitate out to form a mud plug that clogs the shipping channels and thus hampers access to Hai Phong’s economically important port. To correct this situation, frequent dredging is required to allow the ships to pass.

In this study we are developing an optical satellite imagery processing method to study sediment transport so as to optimise costly and fastidious field data acquisition programmes. The sediment transport and coastal dynamics studies are part of the preliminary studies for port and marine facility engineering works as well as locating the areas to dredge. These studies are also being carried out to update old bathymetric maps (depth charts) and to check local maps’ reliability.