Abstract
Confined meandering rivers are bounded between valleys and they are
limited in their lateral migration compared to free meandering ones. In
this study, we designed a model-based analysis to investigate types of
confined meandering rivers. To simulate cases, we used the model
developed by (Bogoni et al. 2017) based on a semi-analytical solution
for flow and bed morphology ((Zolezzi and Seminara 2001). According to
the result of (Lewin and Brindle 1977) the categorization of this type
of meandering river should be based on the potential of evolution. We
defined a confinement ratio as the ratio between the confined valley
width and the meander belt width that the river would theoretically
reach without geological confinement. Such unconfined meander belt width
has been computed through long-term morphodynamic model simulations.
This differs from previous work (Camporeale et al. 2005),
semi-empirically suggesting an unconfined meander belt being nearly 3
times the modeled, linearly most unstable, intrinsic meander length. Our
results indicate the existence of four different types of confined
meandering rivers, which represents the most important point of this
work. Compared to previous work, our classification adds a new class and
reclassifies one of the previous types. Our proposed classes are;
“Moderately confined condition” for confinement ratio in the range
0.1-1, “Strongly confined condition” for confinement ratio in the
range 0.03-0.1. For a smaller confinement ratio than 0.03 we obtain a
low sinuosity, single thread river, and for a confinement ratio greater
than 1, we retrieve a free meandering river. Preliminary testing of our
model-based classification with data from real confined meandering
rivers shows promising results.