Why river bends can move across a floodplain
In many meandering rivers, flow erodes the outside of a bend and deposits sediment on the inside. Curving flow redistributes speed and sediment transport across the channel. Repeated erosion and deposition can shift the bend sideways, so a river's route is not permanently fixed in place.
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A bend changes its own banks
Water moving through a river bend develops a complex three-dimensional flow pattern. Faster flow and stronger erosion commonly occur near the outer bank, while sediment can accumulate on the inner bank as a point bar.
Removing material from one side and adding it to the other gradually shifts the channel. Over time, the bend may migrate across the floodplain.
A meander is an evolving landform. Its shape reflects interactions between flowing water, sediment, bank strength and the surrounding terrain.
- Outer-bank erosion can enlarge a curve.
- Inner-bank deposition builds a sediment bar.
- Continued movement can bring neighbouring bends closer together.
A cutoff may eventually create a shorter channel and leave an abandoned loop. Not every bend behaves identically, because vegetation, rock and engineering structures can constrain the banks.