FLUVIAL PROCESSES

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FLUVIAL PROCESSES

• STREAM FLOW
• STREAM HYDROGRAPH
• EROSION, TRANSPORT
• DEPOSITION

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STREAM FLOW

• Stream flow (discharge) usually expressed in
  Cubic Meters per Second (CMS) or CFS.
• Discharge commonly measured in the field.
• Stream width (m or ft), depth (m or ft), and the
  flow of water (m/s or ft/s) at a cross-section of
  a stream. (Q WDV)
• Stream flow is a rate of the amount of water
  moving past a given location per unit of time.

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• DISCHARGE QAV
• discharge area (WxD) x velocity

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Erosion, Transportation and Deposition
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Stream Erosion

• Detachment of material from the bed or sides of
  the channel
• Flowing water erodes in three ways
• Solution (Corrosion)
• Abrasion (Corrasion)
• Attrition
• Hydraulic action

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Stream Hydrograph
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Stream Transportation

• Transportation is the movement of earth material,
  in this case, by water.
• As particle size increases, so does the velocity
  needed to transport it.
• Transport depends on an appropriate balance of
  forces within the transporting medium.

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• Besides velocity what else might play a role in
  the particle size that is moved?
• Slope
• Steeper the gradient larger the particle sizes
• Less steep gradients smaller particle sizes

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SEDIMENT TRANSPORT
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• Once a particle is entrained, it tends to move as
  long as the velocity of the medium is high enough
  to transport the particle horizontally. Transport
  can occur in four different ways
• Suspension
• Saltation
• Traction
• Solution
• Particle weight, size, shape, surface
  configuration, and medium type are the main
  factors that determine the process.

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Stream DEPOSITION

• Reduction in slope, velocity and discharge
  results in fall of ability to move sediments and
  hence deposition.
• Deposition results in distinct landforms (Well
  discuss these in next class).

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Normal Flow
Flood Increased discharge and erosion!
Post-flood new bars deposited
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GENERAL CONCLUSIONS
Low Order Streams
Intermediate Order Streams
High Order Streams