Semicentennial Response of a Bifurcation Region in an Engineered River to Peak Flows and Human Interventions

Chowdhury, M. Kifayath; Blom, A.; Ylla Arbos, C.; Verbeek, Merel C.; Schropp, Max H.I.; Schielen, R.M.J.

doi:10.1029/2022WR032741

Semicentennial Response of a Bifurcation Region in an Engineered River to Peak Flows and Human Interventions

Title

Semicentennial Response of a Bifurcation Region in an Engineered River to Peak Flows and Human Interventions

Author

Chowdhury, M. Kifayath (TU Delft Rivers, Ports, Waterways and Dredging Engineering)
Blom, A. (TU Delft Rivers, Ports, Waterways and Dredging Engineering)
Ylla Arbos, C. (TU Delft Rivers, Ports, Waterways and Dredging Engineering)
Verbeek, Merel C. (Rijkswaterstaat)
Schropp, Max H.I. (Rijkswaterstaat)
Schielen, R.M.J. (TU Delft Rivers, Ports, Waterways and Dredging Engineering; Rijkswaterstaat)

Date

2023

Abstract

A bifurcation in an engineered river system (i.e., fixed planform and width) has fewer degrees of freedom in its response to interventions and natural changes than a natural bifurcation system. Our objective is to provide insight into how a bifurcation in an engineered river responds to peak flows and human interventions. To this end, we analyze the change in hydraulics, bed level, and bed surface grain size in the region of two bifurcations in the upper Rhine delta in the Netherlands over the last century. We show that, over the last two decades, the water discharge in one bifurcate (the Waal branch) has steadily increased at the expense of the other. This gradual increase in the water discharge of the first branch is associated with its erosion rate being larger than the other branch. The quick succession of two or three peak flow events (1993, 1995, and 1998) caused rapid sediment deposition over the upstream part of the bifurcate that has gradually lost discharge, which seems to have triggered the slow change in flow partitioning.

Subject

River bifurcation
Rhine River
Netherlands
Flow partitioning
Peak flow
Engineered Rivers
Tipping point
Gravel bed rivers
Upper Rhine delta
Flood