Analysis of airborne LiDAR as a basis for digital soil mapping in Alpine areas
Especially in mountainous regions like the Alps the formation of soil is highly influenced by relief characteristics. Among all factors included in Jenny's (1941) model for soil development, relief is the one most commonly used in approaches to create digital soil maps and to derive soil properties from secondary data sources (McBratney et al. 2003) Elevation data, first order (slope, aspect) and second order derivates (plan, profile and cross sectional curvature) as well as complex morphometric parameters (various landform classifications, e.g. Wood 1996) and compound indices (e.g. topographic wetness indices, vertical distance to drainage network, insolation) can be calculated from digital elevation models (DEM) However, while being an important source of information for digital soil mapping on small map scales, "conventional" DEMs are of limited use for the design of large scale conceptual soil maps for small areas due to rather coarse raster resolutions with cell sizes ranging from 20 to 100 meters. Slight variations in elevation and small landform features might not be discernible even though they might have a significant effect to soil formation, e.g. regarding the influence of groundwater in alluvial soils or the extent of alluvial fans. Nowadays, Airborne LiDAR (Light Detection And Ranging) provides highly accurate data for the elaboration of high resolution digital terrain models (DTM) even in forested areas. In the project LASBO (Laserscanning in der Bodenkartierung) the applicability of digital terrain models derived from LiDAR for the identification of soil relevant geomorphometric parameter is investigated. Various algorithms which were initially designed for coarser raster data are applied on high resolution DTMs. Test areas for LASBO are located in the region of Bruneck (Italy) and near the municipality of Kramsach in the Inn Valley (Austria) The freely available DTM for Bruneck has a raster resolution of 2.5 meters while in Kramsach a DTM with a cell size of 1 meter is used.