Fluvial Systems

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Fluvial Systems

• River Landforms

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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

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Physics of Stream Flow
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Sediment Transport

• Suspended Load
• Bed Load
• Solution Load

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Suspended Load
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Solution Load

• Think Ocean Water

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

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Straight Channels

• Inherently unstable
• Most form sand bars which turn into meanders
• Dan Neilens work

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Braided Streams

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

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Braided Stream
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Meandering River

• Mississippi River!

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Meandering River

• Sinuous River with many bends

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Meandering River

• Oxbow Lakes

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Meandering River

• Oxbow Lakes-how do they form?

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Meandering River

• Parts of a river

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Meandering River
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Drainage Patterns

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

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Dendritic

• Tree-like

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

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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

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Deltas

• River Dominated Mississippi River Delta

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Deltas

• Tide Dominated Tides overwhelm freshwater input

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Deltas

• Wave Dominated Longshore current carries
  sediment away

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Alluvial Fans

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

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Alluvial Fans
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How do they match up?

• Will sketch it on board