Geography 323 -- Geomorphology

Fluvial Landforms and Processes

Erosional processes on slopes

  1. raindrop impact

  2. rainsplash erosion

  3. sheet wash (rain wash)

  4. rill erosion

  5. subsurface erosion

    formation of natural pipes as interflow and baseflow erode macropores and fractures in fine sediments
    collapse of the roof of a pipe to form a gully

Fluvial landforms on slopes

Stream Erosion and Sediment Transport

stream competence

stream capacity

types of sediment load

  1. dissolved
  2. traction (bedload)
  3. suspended

Fluvial Morphology

Channel geometry

  1. plan view

    1. meandering
      • sinuous single thread, the most stable and efficient channel geometry (least variable energy distribution) to conduct water and sediment over any surface (e.g. supraglacial streams
      • formed and maintained by erosion of banks and deposition on point bars

    2. braided
      • multiple thread, superimposed meandering channels as discharge and sediment load vary seasonally and diurnally, e.g. semiarid and proglacial streams
      • bars reforms during flood stage, deposition during falling stage that splits subsequent flow
      • different hydraulic geometry at different stages

    3. anatomosing
      • permanent multiple channels and mid-channel bars
      • channel width increases and depth decreases below a threshold for sediment transport and flow splits into deeper more narrow channels

    4. straight
      • either artificial or structurally controlled

  2. longitudinal profile

  3. cross-sectional (hydraulic) geometry

Graded river (G.K. Gilbert)

Network geometry

Basin morphology: fluvial landforms

river valley

stream capture



alluvial fan


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