| Summary: | 2D Free-surface hydraulic modeling tools are commonly used to assess flood hazard for
production of maximal water depth (hmax) maps, as support
for flood risk assessment. High Resolution (HR) topographic data are big data getting
commonly available and used by hydraulic modeling community. Topographical information and
its strategy of inclusion in models, are inputs of great importance for overland flow
hmax calculation. To
strengthen the assessment of confidence level in these deterministic hydraulic models
outputs, uncertainty analysis (UA) and global sensitivity analysis (SA) can provide useful
information that is required by practitioners and decision makers. UA and SA approaches
allow to identify effective strategies to reduce the uncertainty of a model output. In
this paper, developed approach consists in parameterizing three factors which introduce
uncertainty related to HR topographic data use with hydraulic models: the measurement
error (var. E), the level of details of above ground element
representation in DEM (buildings, sidewalks, etc.) (var. S), and the spatial
discretization resolution (grid cell size of a regular mesh) (var. R). Parameter var.
E follows a
probability density function whereas parameter var. S and var. R are discrete operator
choices. The coupling of an environment for parametric computation (Prométhée) and a code
relying on 2D shallow water equation (FullSWOF2D), Promethée-FullSWOF2D (P-FS) tool has
been set up. P-FS tool allows launching directly numerous set of computation using
R software.
1200 simulations of a river flood event scenario were performed on the regular
computational mesh, spatially discretizing a 17.5 km2 urban area (Nice, France). The
aim is to produce UA over points of interests and SA through Sobol index maps
production.
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