Author(s): Morgan Abily; Philippe Gourbesville; Ludovic Andres; Claire-Marie Duluc
Linked Author(s): Philippe Gourbesville
Keywords: Digital Surface Model; High resolution modeling; Flood hazard; Mike 21; TELEMAC-2D
Abstract: Sensitive industrial sites such as nuclear facilities have to consider flood hazard to prevent from a safety failure. For industrial platforms, as for densely urbanized environment, surface structures (like building, walls, road curbs, sidewalks, entrance ramps etc. ) are numerous and impact overland flow patterns. Therefore, inclusion of this system of surface features in methods aiming to estimates flood hazard deserves a special consideration. Aerial topographic data gathering technologies such as LiDAR and photogrammetry can provide highly accurate data about the location and the elevation of these structures. Accordingly, it opens the possibility to incorporate them accurately in high resolution Digital Surface Models (DSM). This paper is focused on possibilities, advantages and limits of high resolution surface information data use within standard categories of 2D hydraulic numerical modeling tools for runoff hazard assessment purpose. Methods to encompass high resolution surface elevation data in standard modeling tools are evaluated and tested. The study is performed on an industrial platform located in Nice (France). A LiDAR and a photogrammetric campaign were carried out by the municipality over a large territory (about 400 km²) with a high level of precision. Horizontal and vertical accuracy of the produced surface elevation data is about 0. 2 m over the studied area. Dissimilar DSM based on these sets of data are generated and compared. Different categories of standard numerical modeling tools based on bi-dimensional Shallow Water Equations (2D SWEs) relying on different discretization possibilities are checked. Runoff scenarios implemented in models are based on recommendation of the French Nuclear Safety Authority from their current project of guide line for protection against flood hazard. Results reveal the feasibility of high resolution DSM use for runoff modeling over industrial and urban site and the clear added value of those new approaches for generating data for modeling systems is enhanced. Important differences occur locally in maximal water depth estimation depending on above ground features representation in DSM and on the used methodology to implement them in 2DSWEs based models. Relevance and limits of different approaches for detailed structures inclusion in models are raised up. In conclusion, recommendations are given for finely-tuned topographic data use with standard 2D numerical modeling tools for high resolution runoff modeling.