Développement d’une méthodologie pour la cartographie du risque d’inondation : application à la rivière de Cavaillon en Haïti

Within a global framework of characterization of floods, rivers and their sediment load in Haiti, the objective of this work is to create decision support tools for the flood risk prevention from hydraulic modeling results and vulnerability estimation. The characterization of the river is presented in the form of flood hazard maps based on water depths and flow velocities. These maps are derived from the results of one-dimensional (1D) and two-dimensional (2D) hydraulic modeling. These models are based on the Saint-Venant equations discretized with a finite-volume scheme. The 1D model is constructed using river cross sections. Several interdistances have been tested to take into account flow singularities in the most complex sections. The 2D modeling is performed on a triangular mesh, denser in the minor bed for greater accuracy and less dense in the floodplains. The simulations were first carried out in steady flow considering the largest flow recorded by the measuring devices. This first work allowed to verify the different hypotheses of the study. Comparisons were made between the two types of models (1D;2D) highlighting the strengths and weaknesses of each. The methodology was then used to simulate the 2016 flood in the Cavaillon city. Discharge hydrographs were created from ATHYS software with NASA satellite rainfall data. These simulations integrate the contributions of the different ravines which turn out to be significant. In addition to the hazard maps, vulnerability maps were created using Saaty’s multi-criteria method. This method assigns a weight to each element considered as an issue according to pre-established criteria in order to make pairwise comparisons. Vulnerability maps of human, material and agricultural issues are obtained by this method. These vulnerability maps are crossed with the hazard maps to obtain the risk maps of the study area.