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TitleNew sensitivity indices of a 2D flood inundation model using Gauss quadrature sampling
AuthorOubennaceur, K; Chokmani, K; Nastev, MORCID logo; Gauthier, Y; Poulin, J; Tanguy, M; Raymond, S; Lhissou, R
SourceGeosciences vol. 9, issue 5, 220, 2019 p. 1-19, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20180290
PublisherMDPI AG
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
NTS31H/03; 31H/06
AreaRichelieu River; Chambly; St-Jean-sur-Richelieu; Saint-Georges-de-Clarenceville; Lacolle
Lat/Long WENS -73.4167 -73.0000 45.5000 45.0000
Subjectshydrogeology; Nature and Environment; Science and Technology; floods; surface waters; rivers; watersheds; models; hydraulic analyses; mapping techniques; stream flow; flow rates; topography; shoals; discharge rates; computer simulations; Richelieu River Watershed
Illustrationslocation maps; satellite images; geoscientific sketch maps; tables; models; photographs
ProgramPublic Safety Geoscience Quantitative risk assessment project
Released2019 05 14
AbstractA new method for sensitivity analysis of water depths is presented based on a two-dimensional hydraulic model as a convenient and cost-effective alternative to Monte Carlo simulations. The method involves perturbation of the probability distribution of input variables. A relative sensitivity index is calculated for each variable, using the Gauss quadrature sampling, thus limiting the number of runs of the hydraulic model. The variable-related highest variation of the expected water depths is considered to be the most influential. The proposed method proved particularly efficient, requiring less information to describe model inputs and fewer model executions to calculate the sensitivity index. It was tested over a 45 km long reach of the Richelieu River, Canada. A 2D hydraulic model was used to solve the shallow water equations (SWE). Three input variables were considered: Flow rate, Manning's coefficient, and topography of a shoal within the considered reach. Four flow scenarios were simulated with discharge rates of 759, 824, 936, and 1113 m3/s. The results show that the predicted water depths were most sensitive to the topography of the shoal, whereas the sensitivity indices of Manning's coefficient and the flow rate were comparatively lower. These results are important for making better hydraulic models, taking into account the sensitivity analysis.
Summary(Plain Language Summary, not published)
A new analysis method for assessing sensitivity in 2D hydraulic modelling is proposed. It is based on perturbation of the statistical distribution of the input variables. The approach was tested and validated over a 45 km long reach of the Richelieu River, Canada. The results show that the predicted water depths were most sensitive to the irregular topography, whereas the sensitivity to the Manning's n coefficient and the flow rate were comparatively lower.

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