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Fluvial Systems

Fluvial Systems. River Landforms. Physics of Stream Flow. Stream velocity - flow velocities are fastest near the center of the stream and slowest near the banks. Thalweg' - the deepest part of the stream Wetted perimeter - the length of the stream bed that is in contact with water.

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Fluvial Systems

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  1. Fluvial Systems River Landforms

  2. Physics of Stream Flow • Stream velocity - flow velocities are fastest near the center of the stream and slowest near the banks. • Thalweg'- the deepest part of the stream • Wetted perimeter - the length of the stream bed that is in contact with water. • Width - width of the stream at a particular point. • Depth - depth of the stream at a particular location. • Reach - any length of a stream

  3. Physics of Stream Flow

  4. Sediment Transport • Suspended Load • Bed Load • Solution Load

  5. Suspended Load

  6. Solution Load • Think Ocean Water

  7. Bed Load Saltation: the process by which particles bounce along on the botttom of a stream

  8. Channel Patterns • Depends on: • Sediment Load • High load more likely to be braided • Gradient (slope of stream) • Low Gradient more likely to be meandering • Human activity • Most straight channels are caused by human activity

  9. Straight Channels • Inherently unstable • Most form sand bars which turn into meanders • Dan Neilens’ work

  10. Braided Streams • High Gradient • Mountainous Regions • Common in glaciated landscape • Series of interconnected channels separated by bars • Carries abundant sediment

  11. Braided Stream

  12. Meandering River • Mississippi River!

  13. Meandering River • Sinuous River with many bends

  14. Meandering River • Oxbow Lakes

  15. Meandering River • Oxbow Lakes-how do they form?

  16. Meandering River • Parts of a river

  17. Meandering River

  18. Drainage Patterns • Influenced by the pre-existing geology and geography of a region • 3 main types • Dendritic • Parallel • Radial

  19. Dendritic • “Tree-like”

  20. Parallel

  21. Radial

  22. Fluvial Landscapes Controlled by Base Level Body of Water Carrying capacity What it can carry Controlled by Slope

  23. Flood Plains • Much of across the river (Arkansas) • flat land that lies next to a stream or a river that experiences periodic times of flooding

  24. Deltas • Landform formed where a river flows into a body of water, be it the ocean or a lake. • River dominated, tide dominated, Wave dominated-three things that control delta development. • Named for Greek Letter Delta, Nile delta looks like

  25. Deltas • River Dominated – Mississippi River Delta

  26. Deltas • Tide Dominated – Tides overwhelm freshwater input

  27. Deltas • Wave Dominated – Longshore current carries sediment away

  28. Alluvial Fans • Fan-shaped features - sediment • Formed at marked change in slope • Mountainous regions • Water carried sediment released when slope changes

  29. Alluvial Fans

  30. How do they match up? • Will sketch it on board

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