| Floods result from the limited carrying capacity of stream channels when
compared to the discharge peak value. The transit of flood waves - with the
associated erosion and sedimentation processes - often modifies local
stream geometry. In some cases this results in a reduction of the stream
carrying capacity, and consequently in an enhancement of the flooding risk.
A mathematical model for the prediction of potential altimetric stream
network evolution due to erosion and sedimentation processes is here
formalized. It works at the regional scale, identifying the tendency of
river segments to sedimentation, stability, or erosion. The model builds on
geomorphologic concepts, and derives its parameters from extensive surveys.
As a case study, tendencies of rivers pertaining to the Valle d'Aosta region
are analyzed. Some validation is provided both at regional and local scales
of analysis. Local validation is performed both through a mathematical model
able to simulate the temporal evolution of the stream profile, and through
comparison of the prediction with ante and post-event river surveys, where
available. Overall results are strongly encouraging. Possible use of the
information derived from the model in the context of flood and landslide
hazard mitigation is briefly discussed. |