Author(s)

D. Bagioli, E. Larcan & S. Mambretti

Abstract

This paper examines the estimation of flooding hazards in the areas adjoining a watercourse. After describing methodologies which differ in the application effort required and in the accuracy expected, it compares the results obtained from their application in two case studies. The reliability of the methods is then discussed. Keywords: flood, hazard, hydraulic models, computer simulations. 1 Introduction Flooding hazard evaluation is a key problem in territorial planning. As is well known, hazard is the probability that an event may happen in a place and in a given time period. Areas at risk of flooding can be identified by means of various methods, each of which involves very different operational difficulties. Briefly, this risk assessment may (a) restrict itself to an overview of the historically flooded areas based on existing data; (b) localize the topographical areas below the level of the water depth in the river, estimating the latter through the peak discharge for a given return period; (c) use a combination of the parameters ‘level’ and ‘distance from the flood origin’ with approximate methods; (d) use a two-dimensional complete model based on the De Saint Venant equations. This paper refers to research using the well-known Flo-2D (O’Brien, [7]) program. This last method, even if it is the most comprehensive and reliable, involves numerous difficulties because the results are extremely sensitive to the boundary conditions and to the description of the land topography. It therefore requires careful and critical analysis.

Keywords

flood, hazard, hydraulic models, computer simulations.