Author(s): Seline Frei; Robert Boes; David F. Vetsch

Linked Author(s): David Vetsch, Robert Boes

Keywords: lateral diversion structure; lateral overflow; lateral weir; overflow embankment; side weir

Abstract: Lateral diversion structures in rivers, such as side weirs or overflow embankments, are common measures to divert a part of the discharge into a lateral retention area or into a flood corridor during larger flood events. The lateral overflow reduces discharge and thus bedload transport capacity in the main channel, leading to local deposition near the lateral diversion structure and sediment aggradation downstream of the structure. The bed level rise may lead to considerably increased lateral overflow compared to the situation without bedload deposition. This should be considered in the design of lateral diversion structures. Systematic morphodynamic 1D, 1D-2D coupled and 2D simulations with the BASEMENT software were carried out to analyse the interaction between lateral overflow and changes in bed level. All modelling approaches are able to reproduce the sediment aggradation downstream of the lateral diversion structure and show increased lateral overflow compared to a simulation without bed level changes. The choice of modelling approach to simulate the lateral overflow depends on the model requirement, data availability and objectives.

DOI: https://doi.org/10.3929/ethz-b-000675921

Year: 2024