This study addresses the challenges of flood risk management in river channels, focusing on the uncertainties associated with determining freeboard requirements after local river widening. The research explores how different widening configurations impact water surface elevation and flow depth, leading to changes in flood risk estimations. By applying statistical methods, the study compares the results with the approaches recommended by the swiss flood protection commission (CIPC) guidelines in 2013. The findings indicate that while widening increases uncertainty in water surface elevation, it also significantly reduces flow depth, potentially offsetting the need for higher levees. The study concludes that current methods may overestimate the necessary freeboard, especially under extreme flood conditions where variability decreases. This research provides insights into optimizing flood management strategies in revitalized river sections, offering potential pathways for more accurate risk assessments.