Author(s): Nurullah Ozbey, , U. Sidar Gül

Linked Author(s):

Keywords: 2D Hydraulic Model; Uncertainty Budget; Monte Carlo Method; GUM Method; HEC-RAS;

Abstract: In this study the combined uncertainty of a two-dimensional (2D) hydraulic model expanded at 95% confidence level is estimated and the uncertainty budget for the model outputs is attempted to be constructed. It has been shown that many uncertainty sources in the inputs as well as the procedure applied have a significant impact on the accuracy of two-dimensional hydraulic modelling: the uncertainties in the model inputs due to variations in Manning’s ‘n’ Coefficient (M‘n’C) assigned, the bridge modelling methods, the equation sets; Diffusion Wave (DW) and Full Momentum Equations (FM) employed and the geometric data sets for the same river system in the Black Sea Region of Turkey are assessed. To estimate an appropriate M‘n’C for a river system with 2D flow area is a daunting task. It is widely accepted in scientific communities that the uncertainty in the best estimate of the roughness coefficient for a river system is around 20 to 25 percent. Therefore, any attempt to quantify uncertainty in assigned M‘n’C must be based on a sample large enough to obtain statistically significant results. To achieve this task, Monte Carlo Method (MCM) is utilized to estimate the contribution of the likely variations of M ‘n’ C and other inputs of model in ‘the combined expended uncertainty at 95% confidence level in two-dimensional hydraulic modelling’.

DOI: https://doi.org/10.3850/38WC092019-0523

Year: 2019