Constructing uncertainty budget for a two-dimensional hydraulic model

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 assigned, the bridge modelling methods, the equation sets; Diffusion Wave and Full Momentum Equations 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 and other model inputs of model for a river system with a wide 2D flow area is a daunting task. Therefore, any attempt to quantify uncertainties in the assigned values must be based on the samples large enough to obtain statistically significant results. To achieve this task, Monte Carlo Method is utilized to estimate the contribution of the likely variations of model inputs onto ‘the combined expended uncertainty at 95% confidence level in two-dimensional hydraulic modelling’.