Very high resolution DEM in dissected landforms: data acquisition and application tests

Very high resolution DEMs are now available in highly dissected areas such as badlands. These spatial digital elevation data offer new means for erosion processes knowledge,for monitoring and for modelling eroded landforms. We intend here to present DEMs with 'Very High Spatial Resolution' i.e. with pixel size of about one meter or less and a Z accuracy better than one meter. The capabilities of these new data acquisition techniques can stimulate new developments in geomorphologic research. After a short description of different techniques of DEMs generation from stereo images and LiDAR with their related accuracy, we recall some of the different mathematical transforms of elevation that represent useful parameters in geomorphology. In order to expose some of the capabilities of these new data, we present several case studies conducted in the marly watersheds of the Draix Research Environmental Observatory (ORE), part of the French Alps. These case studies concern the thalweg network extraction and its complexity analysis using DEM at 2 meters resolution (and others at 4, 8 and 20 meters resolution). The paper also deals with the automatic extraction of gullies according to a series of morphologic criteria, which can be useful for the management of projects for reducing erosion. Finally, Terrestrial Laser Scanning proves to be extremely valuable when high accuracy topographic measurements are needed for identifying rill network initiation and evolution on elementary slopes and for erosion balance assessment.