Methods devoted to the assessment of geomorphic changes can be used to
identify geomorphologically unstable areas, to quantify processes intensity,
and to compute sediment budgets. Digital elevation models (DEMs) built
from repeated topographic surveys can be used to produce DEM of
Difference (DoD) maps whose analysis allows to study morphological
changes in slopes and channels from the quantitative (scour and fill
changes in volume) and the qualitative (spatial patterns of erosion and
deposition) perspectives (Scheidl et al., 2008; Theule et al., 2012; Picco et
al., 2013). The activity carried out by CNR IRPI (PP4) in the frame of the
SedAlp project focused on the analysis of multi temporal high-resolution
Digital Terrain Models (DTMs) derived by Airborne and Terrestrial LiDAR.
The aim is to analyse surface changes due to erosion and deposition in a
bedload and two debris-flow prone basins in the Eastern Italian Alps
(Strimm, Gadria and Moscardo pilot areas). The analysis was carried out at
different temporal and spatial scales basically related to the typology of the
adopted surveying method. In Gadria and Strimm catchments, where two
airborne LiDAR (2005 and 2011) are available, geomorphic changes
induced by debris flows and landslides were investigated at catchment
scale. DoD results have been then compared with field estimations stored
in a historical database. In the Moscardo catchment, Terrestrial Laser
Scanner (TLS) has been used to survey three representative areas of the
catchment in a small time window (August 2011-October 2012). Results of
volumetric budgets of the surveyed sediment source areas derived from
DoD analysis have been compared with debris-flow volumes estimated
from flow stage measurements at the instrumented channel reach.
