Erosion and Deposition

Complex topographic and depositional features are associated with the Mississippi River Alluvial Plain. All the features are due to erosion or deposition by the Mississippi and its tributaries except for loess, which was deposited by wind.

Erosion, sediment transport, and deposition can occur in relatively stable conditions are are natural processes essential to the dynamic stability of rivers and streams. When these processes become extreme or out of balance, erosion and transport become degradation (left) and deposition becomes aggradation (right).

Human modifications to the landscape strongly influence triggers to instability, accelerating the erosion potential and altering sediment transport and flow regimes of channels. See below: The Walla Walla River in December of 1964 defies an attempt at channelization and re-creates meanders, point bars, pools, and riffles.