『Abstract
Most rivers on Earth today flow as a single channel, in some
cases with occasional islands, and follow a more ore less sinuous
course. However, single-thread channels have proven difficult
to reproduce and study experimentally: experimental self-formed
channels tend to widen and subdivide, leading to a braided pattern.
Cohesive sediment has been the main mechanism studied for stabilizing
banks and producing a single-thread channel. We show how laboratory
experiments using vegetation to stabilize banks can organize the
flow and convert the platform morphology from braided to single-thread.
Our experimental strategy, a repeated cycle of short periods of
high water discharge alternating with longer periods of low discharge
accompanied by plant seeding and growth, leads to the evolution
of a dynamic self-maintaining single-thread channel with well-defined
banks and floodplain. By eliminating weak flow paths, the vegetation
“corrals” the water into a single dominant channel until the reduction
in total wetted width leads to a new self-organized state in which
the flow removes vegetated area as fast as it is produced. The
new channel is deeper and has a broader distribution of depths
than the braided one, with channel size adjusted to carry almost
all the flood flow. The resulting system maintains a dynamic steady
state via similar mechanisms to those that operate in meandering
channels in the field, specially erosion at the outside of bends,
bend growth, and bar development. Our methodology provides a basis
for experimental development of self-sustaining high-amplitude
meanders and has applications for river management and basic research
purposes.
Keywords: braided channels; vegetation; meandering; self-organization;
floodplains; experimental studies.』
Background and motivation
Experimental methods
Results
Self-organization and dynamic steady state
Mechanisms for maintaining steady state
Conclusions
Acknowledgments
References cited