Reducing uncertainties in flood inundation outputs of a two-dimensional hydrodynamic model by constraining roughness

The consideration of uncertainties in flood risk assessment has received increasing attention over the last 2 decades. However, the assessment is not reported in practice due to the lack of best practices and too wide uncertainty bounds. We present a method to constrain the model roughness based on measured water levels and reduce the uncertainty bounds of a two-dimensional hydrodynamic model. Results show that the maximum uncertainty in roughness generated an uncertainty bound in the water level of 1.26m (90% confidence interval) and by constraining roughness, the bounds can be reduced as much as 0.92m.