EAS201 Lecture Notes - Lecture 14: Alluvium, Time-Based Currency, Point Bar
22 Mar 2020
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Document Summary
Shape of the river channel and the evolution of channel shape over time. River is directly incised in bedrock, typical of the headwaters (upstream) Further downstream in lower gradient environments and the channel morphology changes more rapidly. Multiple channels separated by bars (sand and gravel between channels) Channels and bars change position and size as the stream erodes and deposits sediment. Forms large sinuous loops (each bend is a meander) Common in fine-grained alluvium and in low gradient channels. Coarser bed material is located on the outside of meanders where flow is faster. If the migration of a meander slows due to a more resistant bank material resulting in slower erosion, the meander behind it may catch up. The more shallow the water, the weaker the force is. Minor changed in landscape have a larger effect. Erosion on the other bank causes cutbank, and downstream migration of meander. Get maximum erosion and velocity on the outer bank.
