Abstract
Fluvial hazards of river mobility and flooding are often problematic for
road infrastructure and need to be considered in the planning process.
The extent of river and road infrastructure networks and their tendency
to be close to each other creates a need to be able to identify the most
dangerous areas quickly and cost-effectively. In this study we propose a
novel methodology using random forest (RF) machine learning methods to
provide easily interpretable fine-scale fluvial hazard predictions for
large river systems. The tools developed provide predictions for three
models: presence of flooding (PFM), presence of mobility (PMM) and type
of erosion model (TEM, lateral migration, or incision) at reference
points every 100 meters along the fluvial network of three watersheds
within the province of Quebec, Canada. The RF models uses variables
focused on river conditions and hydrogeomorphological processes such as
confinement, sinuosity, and upstream slope. Training/validation data
included field observations, results from hydraulic and erosion models,
government infrastructure databases, and hydro- geomorphological
assessments using 1-m DEM and satellite/historical imagery. A total of
1,807 reference points were classified for flooding, 1,542 for mobility,
and 847 for the type of erosion out of the 11,452 reference points for
the 1,145 km of rivers included in the study. These were divided into
training (75%) and validation (25%) datasets, with the training
dataset used to train supervised RF models. The validation dataset
indicated the models were capable of accurately predicting the potential
for fluvial hazards to occur, with precision results for the three
models ranging from 83% to 94% of points accurately predicted. The
results of this study suggest that RF models are a cost-effective tool
to quickly evaluate the potential for fluvial hazards to occur at the
watershed scale.