IAHR Training Course on Shallow mixing interfaces and their role in controlling flow, mixing and sediment transport at river confluences

[Elsa Incio]

IAHR TRAINING COURSE

 

Shallow mixing interfaces and their role in controlling flow, mixing and sediment transport at river confluences

27 October - 3 November 2025

ONLINE

 

The short course will discuss in depth the physics of shallow mixing layers and shallow mixing interfaces and of the related transport processes in both canonical configurations and in natural environments (river confluences) across a wide range of scales. The course will discuss how the structure and spatial development of the mixing interface are affected by density contrast between the incoming flows, channel bathymetry, confluence angle, bed roughness, etc. It will present the state of the art in terms of laboratory, field and numerical studies used to investigate the flow structure and dynamics of such flows. It will show the critical role played by large-scale turbulence in controlling mixing, sediment transport processes and spatial patterns of water quality and biodiversity at river confluences, which are integral and ubiquitous components of all riverine systems. Besides their highly complex flow structure at the local-scale, confluences are, at the basin-scale, nodal points of river connectivity, which is related to the pathways enabling the motion and exchange of water, organisms, sediment, organic matter, nutrients and energy. Hence, river confluences impact on sediment routing, pollution transport and water quality, navigation, fishing and biodiversity changes with large socio-economic and political implications on the real-world. At the end, river confluences are nodes of river networks where water conservancy projects are planned and designed to optimize the integrated management of complex river basins. The course will emphasize a synergetic approach in which experimental and numerical techniques are jointly used to reveal new knowledge and explain phenomena observed at natural river confluences under a wide range of conditions and scales. A preliminary list of the main topics covered is given below. The course will also offer the participants the chance to directly interact and exchange research ideas with the lecturers.

 

The course is co-organized by the IIHR Fluvial Hydraulics Committee (Prof. George Constantinescu, Univ. Iowa, USA) and the IIHR Fluid Mechanics Committee (Prof. Vlad Nikora, Univ. Aberdeen, U.K.).  The theoretical modeling and experimental studies module will be led by Dr. Sebastien Proust (INRAE, France). Prof. Carlo Gualtieri (Univ. Federico II Naples, Italy) will lead the module focusing on field studies of flow, mixing, sediment transport and ecological processes at river confluences. Prof. George Constantinescu will cover eddy-resolving numerical studies of confluent flows in idealized geometries and natural river confluences.

 

The course will take place over 6 days with 2 hours of zoom lectures following by questions and answers Each of the main three topics will be covered in approximatively 4 hours. A final 1 hour roundtable to bring together and foster the main outcomes of the course is planned during the last day.

 

1. Theoretical and laboratory studies of shallow mixing layers

• Shallow turbulent mixing layers in open-channel flows
• Shallow mixing layers developing (i) over spanwise-heterogeneous bed, and (ii) in partly vegetated channel.
• Shallow mixing layers in compound open channels
• Interplay between flow structures in shallow mixing layers

2. Field studies of river confluences

• River Confluences: an introduction
• River Confluences as nodal points of connectivity in a river basin
• Field instrumentation
• Data post-processing and analysis
• Field studies of river confluences on different scales
• Field observations in the Amazon River
• Field observations in the Yangtze River
• Field observations in the Yarlung Zangbo-Brahmaputra River
• Remotely sensed studies
• Conclusions

3. Numerical simulations

• Shallow mixing layers and shallow mixing interfaces in constant depth, wide channels: Effects of velocity ratio, confluence angle and channel curvature
• Flow and mixing processes at natural river confluences with a concordant bed
• Shallow mixing interfaces with density contrast between the incoming streams in constant depth, wide channels
• Density contrast effects on flow and mixing at natural river confluences with a concordant bed
• Flow structure and mixing processes at natural river confluences with a discordant bed

For more info visit the course page

Elsa Incio    Madrid Office Manager  International Association for Hydro-Environment Engineering and Research (IAHR)  Tel. +34 91 335 7919 elsa....@iahr.org      Website ∙ X ∙ Facebook ∙ Instagram ∙ LinkedIn ∙ WeChat   Join us for the 42nd IAHR World Congress "Drive the Change: Management in the Era of Digital Water & Transitions| Bari, Italy | 28 June - 2 July 2027  Keep updated! Subscribe to our monthly e-newsletter NewsFlash World