Optical high-resolution, multi-date remote sensing imagery is highly effective at detecting changes in surface planform features of a river system that are directly visible from above, such as channel width, channel position, channel sinuosity, channel bar morphology, and bankline migration, since these all involve visible changes in the water-land boundary or exposed bar surfaces over time; however, remote sensing imagery cannot directly and accurately measure subsurface or volumetric hydraulic parameters that are not expressed as a visible planform signal, such as water depth (requires bathymetric/sub-surface measurement), discharge (requires simultaneous velocity and cross-sectional area data), floodplain aggradation (a vertical, often subsurface sedimentation process), and flood stage/water level height (a vertical measurement not directly readable from a planform image).