Studying Stream Morphology With Airborne Laser Elevation Data



Much progress has been made linking the fields of geomorphology, hydrology, ecology, and tectonics over the past approximately 20 years using digital elevation models (DEMs) to study stream processes. DEMs forming the basis of such research were created by interpolating between contour lines digitized from topographic maps, which were generated from aerial photographs. With pixel sizes of 10–90 meters on each edge, these grids allowed investigators to make measurements of parameters such as stream gradient and contributing drainage area over entire channel networks; these parameters also found use as inputs for basin-scale models of stream erosion and sediment transport [e.g., Wobus et al., 2006].

However, the accuracy of these “traditional” DEMs varies spatially because map contour interval (typically 3–20 meters) and density (set by landscape gradient) dictate the resolution of information available to interpolate an elevation value for each pixel on the grid. Thus, traditional DEMs miss many fine-scaled features, particularly those in low-relief terrain. DEMs generated from space shuttle or satellite radar surveys have similar pixel resolution (10–90 meters) but do not measure land surface elevations in forested regions, limiting their applicability for studies of channels.