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ABSTRACT
This paper reports the results of an experimental series carried out to study flow and sediment distribution in a 90° channel diversion. Each experiment is performed letting the system evolve until an equilibrium state is achieved. The obtained results confirm that sediment tends to move into the lateral branch as suggested in previous studies. The experiments also show a dependence of the phenomenon on the total water discharge and the bed topography evolution in the diversion area. These results have not been previously reported. Over a threshold value of momentum flux ratio, a depression is formed in the main branch that acts as a blocking mechanism for sediment, capturing and directing it towards the lateral branch. This study highlights the importance of interrelations at fluvial diversions between the evolution of bed topography, flow characteristics and sediment distribution.
Acknowledgements
This work has been developed within the framework of the project “Problemática Socio-Ambiental del Delta del río Patía”. The authors thank the GITS research group for its economical and personal help and the Ministerio de Educación y Ciencia (Spain) for the financial support through project CGL 2009-13039 and the grant given to AH for the development of his PhD.
Notation
| Bl | = | lateral branch width (m) |
| Bm | = | main branch width (m) |
| Cl | = | lateral branch sediment concentration (dimensionless) |
| Cm | = | main branch sediment concentration (dimensionless) |
| Mr | = | momentum flux ratio (dimensionless) |
| Ql | = | lateral branch water discharge (m3 s–1) |
| Qm | = | main branch water discharge (m3 s–1) |
| Qsl | = | lateral branch solid discharge (m3 s–1) |
| Qsm | = | main branch solid discharge (m3 s–1) |
| QT | = | main channel total water discharge (m3 s–1) |
| rQ | = | water discharge ratio (dimensionless) |
| t | = | time since the beginning of the experiment (s) |
| vl | = | lateral branch mean flow velocity (m s–1) |
| vm | = | main branch mean flow velocity (m s–1) |
| = | water density (kg m–3) |