2021 Volume 77 Issue 2 Pages I_727-I_732
In 1997, two artificial cutoffs were performed in the Ichilo River in order to save the usability of a port from the menace of a natural cutoff. In here, we want to analyze the implications of those two artificial cutoffs in the planform of the Ichilo River using 2D numerical simulations. The numerical model used for the simulations is a modified version of the model of Asahi et al. where we expanded a module for the treatment of neck cutoffs in large scale rivers of the Bolivian Amazon such as the Ichilo. We tested the capabilities of the numerical model to simulate large-scale meanders in the short to medium term. The initial planform shape corresponded to 12 meander bends based on the planform shape of the Ichilo river in 1994, with different geometric characteristics, variable channel width and variable discharge. We observed that the model is sensitive to smoothing techniques of the planform, which is a common technique to obtain stable numerical simulations but results in unrealistic planform shapes. The numerical simulations present us the planform evolution of the Ichilo River without the two artificial cutoffs performed in 1997. The results showed that the development of the natural cutoff would have left the port located in an oxbow lake. The migration trends also indicate that the river would have moved toward the northeastern side of the city of Puerto Villarroel.
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