Author(s): A. Paquier; E. Mignot
Linked Author(s):
Keywords: 2D model; Shallow water equations; Calibration; Uncertainty; Sensitivity analysis; Flood
Abstract: In case of wide and built-up flood plains, 2D modelling is necessary to obtain a convenient view of the flows during flooding. The complexity of these flows requires possible modelling of supercritical and specific representation of hydraulic structures. Uncertainty of the results remain high because of hazardous events as dike breaching or because of lack of data such as the local rainfall. Calibration is usually performed by adjusting calculated peak water levels to flood marks. Information about extent of the flooded area or time of arrival or any other information should also be used to reduce uncertainty. Two flood events, the 1999 flood of the coastal Agly river flood plain and the 1988 flood in the city of Nimes are described. On the first event, results of the calibration accuracy are provided in term of average deviation; locally, the difference between calculated peak water level and corresponding flood mark is high because the description of the flood plain does not take into account the buildings in a detailed way and because the influence of infiltration and other secondary processes could not be modelled. On the second example, representing a dense built-up area, a sensitivity analysis was performed in order to identify the parameters that may explain local differences in spite of the representation of the buildings. Higher uncertainty seems to come from the topography including description of the possible storage areas, from flow and rainfall inputs and from specific hazardous events (car blockage or any event due to fixed or mobile obstacle).
Year: 2003