ABSTRACT
In bifurcating river systems, river interventions affect the water levels in all of the downstream branches. An accurate impact quantification is therefore important. However, the hydraulic models used to estimate these impacts are inherently uncertain. This study assesses the impact of a dike set-back and its uncertainty in a bifurcating river system using a 1D network model. The results show that the presence of the river bifurcation strongly decreases the maximum water level reduction and the uncertainty of it. Generally, the uncertainty of the impact scales with the impact itself. However, in a bifurcating river system, the hydraulic roughness parameters that cause the uncertainty in the impact, also have an own influence on the discharge distribution. These interactions all affect the uncertainty of the impact in a bifurcating river system. The knowledge on these interactions can aid in the decision process for the future design of interventions near bifurcations.
