High-resolution Lidar-derived Dtms: Some Applications for the Analysis of the Headwater Basins’ Morphology

High resolution topographic data have the potential to differentiate the main morphological features of a landscape. For the purpose of this study the Digital Terrain Models (DTMs) were derived at different resolution from the last pulse LiDAR data by filtering the vegetation points. We tested the potential of high resolution DTM in the analysis of river bed morphology, channel heads identification, and potential slope stability mapping. The study was conducted in two headwater catchments located in the eastern Italian Alps where a high-quality set of LiDAR elevation data was available. The results revealed the effectiveness of the finest DTM resolution of (∼ 0.5 / 1 m) in the recognition of river morphology giving the potential to distinguish the riffle-pool and step-pool reaches, and in the analysis of hillslope/valley morphology where the landform curvature was useful to depict channel heads locations and hollows morphology. Otherwise the progressive finer DTM resolution does not necessarily improve the interpretation of slope stability processes by a terrain stability model especially if landslides occur at a spatial scale significantly greater than cell size. The analysis on the Stability Index (SI) distribution indicates the DTM scale of 10 m as the optimal for mapping landslide scars. A higher percentage of landslide areas is mapped likely unstable using a 10 m DTM than DTMs at finer or lower resolution. Using DTM scales smaller than 10 m the shallow landsliding processes are obscured by smaller scale of surface morphology variability, while scales larger than 10 m result in loss of resolution that degrades the results.