Abstract
This PhD focuses on the modeling of urban floods and the consideration of buildings. Flood management provided by public services is based on two-dimensional numerical models. These models do not or partially represent the exchanges between streets and buildings. However, feedback and photos report that water enters homes, threatening people and their property. While some buildings act as reservoirs and temporarily or even permanently store part of the volume of the flood, others are crossed by the flows if they are connected to several streets. To characterize the effect of buildings on flooding, a new numerical model is proposed, based on the integration of an additional source term in the 2D shallow water equations. The concept of the street-building model is inspired by compartment models, where street and building exchange a flow through openings, such as doors and windows. The transverse flow is controlled by discharge laws, developed from three-dimensional simulations of real-scale openings. The exchange laws are based on the weir and orifice laws from the literature, and the discharge coefficient is determined by limiting the error on the flow calculated numerically. Laws with a tolerance of 30 % error on the discharge passing through an opening are established. The street-building model is applied in a synthetic street. By comparing with a classic model in which the buildings are waterproof, considering the street-building exchanges significantly reduces the peak flow (- 25 %) and the maximum height (- 15 %) at the exit of the buildings, while maximum speed increases along buildings (+ 25 %). A sensitive analysis to geometric and hydrodynamic parameters is carried out, with the aim of identifying configurations for which the buildings must be considered. In addition, this analysis makes it possible to characterize the influence of each of the parameters on the street-building exchanges.The model is also used in a real case corresponding to the flooding of the Richelieu district (Nîmes, France) which is exposed to urban runoff. The effect of buildings is studied in this complex geometry, whose average North-South slope is 1 %. Again, the modifications are significant in the street compared to the classic model, with local variations ranging between +/- 50 cm on the maximum height, +/- 1 m/s on the maximum speed and +/- 40 % on the flow rates peak within the street network. Various realistic situations are considered, by modifying the state of the openings (open/closed, cofferdams) and by imagining cellars capable of significantly increasing the total volume stored in the buildings. As the water level reached in buildings is directly correlated with damage to people and equipment, the hydraulic results are also interpreted in terms of evacuation of people and economic residential damage. The new proposed model offers new socio-economic perspectives, as well as new communication and information tools for better flood management.