Sar-based bathymetry

Abstract

Although microwaves cannot penetrate into the water body, SAR can yield information on shallow-water bathymetry or underwater bottom topography. This is achieved indirectly by means of sensing variations in the sea surface roughness over bathymetry when a strong current (usually tidal current) is present. SAR is a very sensitive instrument to sense small variations in the (small-scale) sea surface roughness image. At present, it is not possible to invert reliably SAR images, which are related to sea surface roughness maps, into bathymetric maps by using theoretical models. However, if SAR images are combined with acoustic sounding data acquired from ships, they are of great value for generating bathymetric maps and thus can help to reduce greatly the cost of updating depth charts in tidal areas.