Planform Dynamics and Cut-Off Processes in the Lower Ucayali River, Peruvian Amazon
Por:
Abad J.D., Mendoza A., Arceo K., Torres Z., Valverde H., Medina G., Frias C., Berezowsky M.
Publicada:
1 ene 2022
Resumen:
The Ucayali River is one of the most dynamic large rivers in the world, with high rates of channel migration regularly producing cutoffs. In the lower portion of the Ucayali River, before its confluence to the Marañon River where the Amazon River is born, the increase in water and sediment discharge triggers bends with secondary channels (transitional stage from purely meandering to anabranching), which influence the planform migration rates and patterns of the sinuous channels. Based on remote sensing analysis, a comparison of planform dynamics of bends with and without secondary channels is presented. For the case of a bend with secondary channels (Jenaro Herrera, JH), detailed field measurements for bed morphology, hydrodynamics, bed and suspended load are performed for low-, transitional- and high-flow conditions (August, February and May, respectively). Additionally, a two-dimensional depth average hydraulic model is utilized to correlate observed migrating patterns with the hydrodynamics. Results indicate that the secondary channels have disrupted typical planform migration rates of the main meandering channel. However, at high amplitudes, these secondary channels reduce their capacity to capture flow and start a narrowing process, which in turn increases migration rates of the main channels (meandering reactivation process), suggesting that an imminent cutoff along the JH bend is underway by pure lateral migration or by the collapse into the existing paleochannels. © 2022 by the authors.
Filiaciones:
Department of Research, Education and Development, RED YAKU, Lima, 15084, Peru
Instituto de Ingenieria, Universidad Nacional Autonoma de Mexico04510, Mexico
Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, United States
Facultad de Agronomía, Universidad Nacional de la Amazonía Peruana, Iquitos, 16002, Peru
Department of Civil Engineering, University of Engineering and Technology, Lima, 15063, Peru
Barr Engineering Co, Minneapolis, MN 55435, United States
gold, All Open Access; Gold
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