1. Stream Classification

6. Why classify?

7. Why classify?
1.) a means of understanding and describing the variation within and among streams
2.) a way to select comparable sampling sites
3.) a way to interpret a broader context for how we can extrapolate information gathered at specific sites
4.) an approach for assessing past and possible future states

8. Classification Schemes
Wolman and Miller Method
Rosgen Method
Montgomery and Buffington Method

9. Leopold and Wolman Classification

10. Wolman and Miller Classification
Channel Patterns
….in plan view (bird’s eye)
Straight
Meandering
Braided
Transition between Straight
And Meandering is when
Sinuosity is 1.5

11. (pools and riffles)
Riffles are spaced ~ 5-7 times
the channel width

12. (pools and riffles)

13. `
(pools and riffles)

14. Rosgen Method

19. Stream Succession…..

20. Strengths and Weaknesses of Rosgen Method…..

21. Montgomery and Buffington Method

22. “Process-Based Approach”
Montgomery and Buffington Method
“Process-Based Approach”

23. Process-Based Approach
Streams classified the same not only look similar, they are formed by similar processes.
Basic premise is that streams with similar form (and formative processes) will function similarly.

24. High Transport Capacity
hillslope
channel head
colluvial
cascade
Depositional Reaches
step-pool
plane-bed
pool-riffle
dune-ripple
Montgomery and Buffington, 1997

25. ‘Colluvial’ vs. ‘Alluvial’
Colluvial: unorganized and poorly sorted deposits at the base of a hillslope, formed by gravity.
Alluvial: formed by the action of flowing water, indicated by rounded rocks, distinct channel banks, and organized bed forms.

26. ‘Colluvial’ vs. ‘Alluvial’
Colluvial: unorganized and poorly sorted deposits at the base of a hillslope, formed by gravity.
Alluvial: formed by the action of flowing water, indicated by rounded rocks, distinct channel banks, and organized bed forms.

27. Colluvial Channel

28. Why are colluvial channels important for alluvial river ecosystems?

29. Why are colluvial channels important for alluvial river ecosystems?
Comprise >80% of the channel network
Major pathway for the routing of water, sediment, organic matter, and thermal energy to downstream areas
Unique and/or predator-free habitats for numerous amphibians and invertebrates

30. Process Domains C Channel Head Colluvial Channels 1. Earth Flows
2. Gully Erosion
3. Debris Flows
Fluvial Channel Network

31. 1.) Earth Flow Terrain

32. Copyright © Martin Geertsema 2002
Earthflow at confluence of Muskwa and Chisca rivers, northern British Columbia.
Copyright © Martin Geertsema 2002

33. 2.) Gully Erosion
Gulley erosion in cohesive soils and especially post-fire

34. 3.) Debris Flow Terrain

35. DEFINE LANDSLIDES.

36. DEFINE DEBRIS FLOWS.

38. High Gradient, Confined Channels
Cascades

39. High Gradient, Confined Channels
Poorly organized
cobble and boulder bed
Tumbling flow over large,
protruding grains
gradient ≥ 7%
Cascades

40. High Gradient, Confined Channels
Step-Pool

41. High Gradient, Confined Channels
Interlocking cobbles and boulders
organize into discrete channel-
spanning stone lines that form
alternating drops (steps) and
pools.
Gradient: 4 - 6%
Step-Pool

42. High Gradient, Confined Channels
Cascades
Are they very responsive to change?
Step-Pool

43. High Gradient, Confined Channels
Cascades
Are they very responsive to change?
How / where do organisms seek
refuge during flood events?
Step-Pool

44. High Transport Capacity
hillslope
channel head
colluvial
cascade
Depositional Reaches
step-pool
plane-bed
pool-riffle
dune-ripple
Montgomery and Buffington, 1997

45. Moderate to Low Gradient, Unconfined Channels
Plane Bed
Pool Riffle

46. Moderate to Low Gradient, Unconfined Channels
Plane Bed
Pool Riffle
Are they sensitive to changes in sediment & wood supply and/or discharge?
How / where do organisms seek refuge during floods?

47. Moderate to Low Gradient, Unconfined Channels
Plane Bed
Pool Riffle
Are they sensitive to changes in sediment & wood supply and/or discharge?
How / where do organisms seek refuge during floods?

48. Moderate to Low Gradient, Unconfined Channels
Plane Bed

49. Moderate to Low Gradient, Unconfined Channels
relatively featureless
gravel / cobble bed streams
homogeneous habitat
2 – 4% slope
Plane Bed

50. Plane-Bed Channels

51. Moderate to Low Gradient, Unconfined Channels
Pool Riffle

52. Moderate to Low Gradient, Unconfined Channels
Bedforms: alternating bar / pool
Plan form: sinuous
Gradient: < 2%
Pool Riffle

53. Sebaskachu R (Labrador) - tortuous meandering river developed on marine silt and fine sand.
Copyright © Norm Catto 2002

55. toward banks in riffles)
Convergent Flow
(flow concentrates in
pools causing scour)
Pool
Divergent Flow
(flow spreads out
toward banks in riffles)
Pool

56. toward banks in riffles)
Convergent Flow
(flow concentrates in
pools causing scour)
Pool
secondary
circulation
Divergent Flow
(flow spreads out
toward banks in riffles)
Pool

57. Convergent Flow Divergent Flow Flow Reversal Concept
(flow concentrates in
Pools causing scour)
Pool
Divergent Flow
(flow spreads out
toward banks)
Flow Reversal Concept
During low flows velocity
is higher in riffles
During high flows velocity
is highest in pools.
Pool

59. Where do organisms seek refuge during high flows?

60. Where do organisms seek refuge during high flows?
Floodplain Habitats

61. Copyright © Richard Kesel 2002
Meandering river, Alaska.
Copyright © Richard Kesel 2002

62. Alternating Bars and Pools In Sinuous Channels

63. ‘Forced’ Pool Morphology

64. Braided Streams

65. Extremely Low Gradient, Unconfined Channels
Dune Ripple

68. Bedrock Channels

72. Why are there bedrock channels?

73. Why are there bedrock channels?
Sediment transport exceeds sediment supply
Grain size of sediment is small relative to the transport capacity (channel slope * drainage area)

74. High Transport Capacity
hillslope
channel head
colluvial
cascade
Depositional Reaches
step-pool
plane-bed
pool-riffle
dune-ripple
Montgomery and Buffington, 1997

75. Valley Confinement Channel Gradient Particle Size
High Transport Capacity
hillslope
channel head
colluvial
Valley Confinement
Channel Gradient
Particle Size
cascade
Depositional Reaches
step-pool
plane-bed
pool-riffle
dune-ripple
Montgomery and Buffington, 1997

77. Channel Type
-- Colluvial channels (>10%)
-- Cascade (7-10%)
-- Step-Pool (3-7%)
-- Plane-Bed (1.5-3%)
-- Pool-Riffle (<1.5%)

78. Ecological Implications of Different Channel Types

79. Channel Types & Bed Mobility
Cascade and Step Pool channels typically have an abundance of large, interlocking boulders that limit bed mobility. Benthic organisms can seek shelter in interstitial spaces.
Plane Bed and Pool Riffle channels typically have mobile beds during large floods. Benthic organisms can seek shelter in less mobile areas of the channel.
Dune Ripple channels are fully mobile during most storms. Benthic organisms may be limited to wood.

80. Channel Slope
Particle Size

81. Discuss SPI and transition from bedrock to alluvial reaches [insert figure]