Large Wood Transport-Related Flood Risks Analysis of Lourdes City Using Iber-Wood Model
Résumé
Large wood (LW) accumulations can cause several damages, especially
if the recruited wood is transported during floods down to urban areas, like Lourdes
(France). One of the most serious problems concerning bridges and weirs all around
the world is the formation of LW accumulations, that might be responsible for the
structure’s failure. However, the transport and deposition of LW during floods are very
complex processes, which make predictions of these accumulations’ locations and
potential impacts very challenging. Thus, reducing the LW-related risks is difficult.
Thereby, we are conducting a study to assess the LW-related hazards by applying
a numerical model of the Gave-de-Pau River. The software called Iber-Wood is a
hydrodynamic model based on the 2D Saint Venant equations coupled to a wood
dynamics module that simulates wood transport explicitly. It allows analyzing the
LW accumulations’ formation, depending on several input parameters. The aim of
this study was to simulate wood transport during floods, in order to identify the
potential risks created by the formation of LW accumulations in Lourdes’ city center.
The paper first proposes a framework to calibrate the parameters of LW-supply (flux
and size of logs) based on the typical dataset available in France. It then presents a
preliminary study of the 2D hydrodynamic model showing its potential to identify
preferential storage areas and bridges prone to the formation of LW accumulations.
The calibration phase of the model is not finished yet, but we can highlight some
recommendations on LW-transport modelling from these early stage results.