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Uncertainty in the calibration of effective roughness parameters in HEC-RAS using inundation and downstream level observations.

Pappenberger, F. and Beven, Keith J. and Horritt, M. and Blazkova, S. (2005) Uncertainty in the calibration of effective roughness parameters in HEC-RAS using inundation and downstream level observations. Journal of Hydrology, 302 (1-4). pp. 46-69.

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Abstract

An uncertainty analysis of the unsteady flow component (UNET) of the one-dimensional model HEC-RAS within the generalised likelihood uncertainty estimation (GLUE) is presented. For this, the model performance of runs with different sets of Manning roughness coefficients, chosen from a range between 0.001 and 0.9, are compared to inundation data and an outflow hydrograph. The influence of variation in the weighting coefficient of the numerical scheme is also investigated. For the latter, the empirical results show no advantage of using values below 1 and suggest the use of a fully implicit scheme (weighting parameter equals 1). The results of varying the reach scale roughnesses shows that many parameter sets can perform equally well (problem of equifinality) even with extreme values. However, this depends on the model region and boundary conditions. The necessity to distinguish between effective parameters and real physical parameters is emphasised. The study demonstrates that this analysis can be used to produce dynamic probability maps of flooding during an event and can be linked to a stopping criterion for GLUE.

Item Type: Article
Journal or Publication Title: Journal of Hydrology
Uncontrolled Keywords: GLUE ; HEC-RAS ; Uncertainty ; Flood ; Roughness ; Inundation
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 21271
Deposited By: ep_ss_importer
Deposited On: 08 Jan 2009 11:07
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 15:44
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/21271

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