Hydraulic modeling of flood risk on the scale of an African agglomeration in Cote d’Ivoire

Abstract

In the context of urban flood control, it is essential to develop tools and methods to model surface runoff at the scale of the agglomeration. The process of flooding is relatively common in some regions of the world, Africa remains a continent with particular concerns focused on urban flooding for the unprecedented urbanization, which increases the vulnerability of human societies to flooding. The city of Abidjan, like all African metropolises, is known for its high level of urbanization, which causes enormous damage every year during the two rainy seasons, and flooding remains a major problem today. This risk affects several districts of the capital including the Riviera-Palmeraie district although it is a residential district par excellence and inhabited by the wealthiest Ivorian class. In this study, a hydrodynamic modeling of the district was carried out in order to simulate extreme events and a better knowledge of the attributes of the flow in the urban fabric would have important impacts in a more precise mapping of the risks and thus in their prevention. The flow simulation was performed using the SW2D (Shallow Water 2D) "classical" and "porosity" computational codes developed within the HydroSciences Montpellier (HSM) laboratory. In the absence of accurate and reliable field data, the fine model is considered as a reference model to validate the porosity model. The work of this research is to set up two models, the first was the realization of a fine mesh of the district to make a first simulation and to have more precise results; the second part was the realization of a coarser mesh for the porosity model. The developed model allows to reduce the time of calculation considerably, not only in terms of calculation but also for the creation of the mesh. It is therefore fast enough to consider the production of real-time alerts. Then the model allows a comparison between the two models. The fine model allowed a hydrodynamic reference modeling to validate the porosity model. The results obtained in this thesis, present a point of divergence of a few centimeters between the two models because of the absence of high precision topographic data and the adjustment of the parameters of the porosity model