Large Wood Transport-Related Flood Risks Analysis of Lourdes City Using Iber-Wood Model

International audienceLarge wood (LW) accumulations can cause several damages, especiallyif 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 aroundthe world is the formation of LW accumulations, that might be responsible for thestructure’s failure. However, the transport and deposition of LW during floods are verycomplex processes, which make predictions of these accumulations’ locations andpotential impacts very challenging. Thus, reducing the LW-related risks is difficult.Thereby, we are conducting a study to assess the LW-related hazards by applyinga numerical model of the Gave-de-Pau River. The software called Iber-Wood is ahydrodynamic model based on the 2D Saint Venant equations coupled to a wooddynamics module that simulates wood transport explicitly. It allows analyzing theLW accumulations’ formation, depending on several input parameters. The aim ofthis study was to simulate wood transport during floods, in order to identify thepotential 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 (fluxand size of logs) based on the typical dataset available in France. It then presents apreliminary study of the 2D hydrodynamic model showing its potential to identifypreferential 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 somerecommendations on LW-transport modelling from these early stage results