| Autor: |
Chowdhury, M. Kifayath, Blom, Astrid, Ylla Arbós, Clàudia, Verbeek, Merel C., Schropp, Max H. I., Schielen, Ralph M. J. |
| Předmět: |
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| Zdroj: |
Water Resources Research; Apr2023, Vol. 59 Issue 4, p1-21, 21p |
| Abstrakt: |
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. Plain Language Summary: A river bifurcation is where a river splits into two branches. Water and sediment from the upstream channel are divided between the bifurcation's downstream branches. This division is important for flood risk, freshwater supply, and navigation. Here we investigate the flow division and related changes in bed level and bed surface grain size in the bifurcation region in the upper Rhine delta in the Netherlands over the last century. We find that, over the last two decades, one branch (the Waal branch) has gradually received a larger share of the water discharge at the expense of the other branch. This gradual increase in the water discharge of the first branch seems to be associated with its erosion rate being larger than the other branch. This slow change in the division appears to be triggered by two or three successive peak flows (1993, 1995, and 1998), which caused sediment to deposit at the upstream end of the branch that subsequently started losing discharge gradually. Our analysis shows that peak flows can play a large role in bifurcation development in engineered river systems. Key Points: Water discharge in one branch at a Dutch Rhine bifurcation has slowly increased at the expense of the other bifurcateThis slow change in flow partitioning is associated with one bifurcate eroding faster than the other bifurcateSudden deposition in one bifurcate (due to rapid succession of peak flows and sediment flux coarsening) likely triggered these changes [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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