A simulation model for the radar backscattering cross section of the sea surface has been developed based on the radar imaging mechanism of underwater bottom topography. The model consists of the Navier Stokes equation

the action balance equation and the radar backscatter model. The simulation model is solved numerically using the method of characteristics. The results of the simulation model have been used to study the optimal SAR parameters （frequency

polarization and incidence angle） for mapping underwater bottom topography. It is shown that long wavelengths are required. P band is the optimal band for mapping underwater bottom topography

followed by L

C and X bands. Although mapping underwater bottom topography is independent of the polarization

the VV polarization is the best choice because of its large signal to noise ratio. The incidence angles between 20° to 40° are needed to map underwater bottom topography by spaceborne SAR.