TY - JOUR

T1 - Uncertainty in the calibration of effective roughness parameters in HEC-RAS using inundation and downstream level observations.

AU - Pappenberger, F.

AU - Beven, Keith J.

AU - Horritt, M.

AU - Blazkova, S.

PY - 2005/2/1

Y1 - 2005/2/1

N2 - 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.

AB - 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.

KW - GLUE

KW - HEC-RAS

KW - Uncertainty

KW - Flood

KW - Roughness

KW - Inundation

U2 - 10.1016/j.jhydrol.2004.06.036

DO - 10.1016/j.jhydrol.2004.06.036

M3 - Journal article

VL - 302

SP - 46

EP - 69

JO - Journal of Hydrology

JF - Journal of Hydrology

IS - 1-4

ER -