Question

Assuming there are no major changes in either the discharge of the river or the slope of the channel, which image shows the most likely course of the river in 500 years?

Answer 1

I can’t see the images you mean — could you upload them or describe each option?

Meanwhile, here’s how to pick the most likely image and why:

- With discharge and slope held constant, the dominant process is lateral meander migration: helicoidal flow erodes the outer (cut) bank and deposits point bars on the inner bank. Meanders therefore grow until necks narrow and the river eventually cuts through, forming an oxbow lake and a shorter, straighter channel segment.
- Over a few hundred years (500 yr) you are likely to see one or more meander cutoffs and a displaced meander belt, not a completely new avulsion across the floodplain.
- So the most likely image will show a main channel that is straighter than today with one or more abandoned oxbow loops (cutoff lakes) on the floodplain, or a meander that has migrated laterally in the direction of active bank erosion indicated by the current curvature.

If you upload the images (or tell me which option looks like a straighter channel with oxbows), I’ll pick the best one and explain why.