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Etude expérimentale et numérique de l'inondation d'une zone urbanisée : cas des écoulements dans les carrefours en croix

Abstract : This work deals with the modeling of a flood in an urban environment. Among the various types of urban flood events, it was decided to study specifically the severe surface flooding events which take place in highly urbanized areas. The numerical simulation of such events is usually performed using two dimensional shallow water equation models. However, the abilities of these equations to represent some physical flow processes are restricted, especially when supercritical flows collide in a crossroad. An experimental facility was set up in order to describe the flow structures that occur in a 90° junction of four open channels with supercritical upstream flows. The main flow types were identified, depending mostly on the characteristics and location of the hydraulic jumps that develop. Analytical models were set up in order to predict both the discharge distribution in the downstream branches of the junction and some flow structure characteristics. The fair agreement encountered between analytical models results and experimental measured data confirms that the main flow structures governing the flow pattern development were encountered. The 2D numerical code was then able to simulate the flow patterns observed experimentally. Nevertheless, some discrepancies remain when modeling some local flow characteristics. Eventually, the numerical code was applied to simulate a real severe flooding event: the October 3rd, 1988 flood in Nîmes, France. It was able to simulate the main characteristics of the flood such as the average water depth in each urban zone even though some local flow characteristics could not be accurately represented. It appeared that, in order to reduce the discrepancy between the computed water depths and the flood marks, special attention has to be paid when acquiring the topographical data and estimating the numerical parameter calibration values. Nevertheless, the level of accuracy of the simulation remains limited when comparing the computation results to the available observed information.
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Submitted on : Friday, May 15, 2020 - 11:42:39 AM
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  • HAL Id : tel-02586882, version 1
  • IRSTEA : PUB00018096



Emilie Mignot. Etude expérimentale et numérique de l'inondation d'une zone urbanisée : cas des écoulements dans les carrefours en croix. Sciences de l'environnement. Thèse en Mécanique, Ecole centrale de Lyon, 2005. Français. ⟨NNT : ⟩. ⟨tel-02586882⟩



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