1. Stream Classification

2. Why classify?

3. 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

4. Process-Based Approach

5. 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.

6. ‘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.

7. ‘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.

8. Colluvial Channel

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

10. 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

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

12. 1.) Earth Flow Terrain

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

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

15. 3.) Debris Flow Terrain

16. DEFINE LANDSLIDES.

17. DEFINE DEBRIS FLOWS.

18. [insert video clip]

20. High Gradient, Confined Channels
Cascades

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

22. High Gradient, Confined Channels
Step-Pool

23. 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

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

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

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

28. 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?

29. 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?

30. Moderate to Low Gradient, Unconfined Channels
Pool Riffle

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

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

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

35. 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

36. 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

38. Where do organisms seek refuge during high flows?

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

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

41. Moderate to Low Gradient, Unconfined Channels
Plane Bed

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

43. Alternating Bars and Pools In Sinuous Channels

44. Plane-Bed Channels

45. ‘Forced’ Pool Morphology

46. Wood can also ‘force’ a
pool-riffle morphology in otherwise plane-bed or bedrock reaches.

48. Braided Streams

49. Extremely Low Gradient, Unconfined Channels
Dune Ripple

52. Bedrock Channels

56. Why are there bedrock channels?

57. 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)

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

59. 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

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

62. Ecological Implications of Different Channel Types

63. 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.

64. Spatial Extent of Fish

66. Abundance of Spawning Sites

68. Copyright © William Locke 2002
Headward migration by throughflow and sapping processes. Note the steep, blunt, amphitheatre-like headward scarps. View is from Deadhorse Point overlooking Canyonlands National Park, Utah.The Upper Permian White Rim Sandstone forms a cap for these prominent canyons.
Copyright © William Locke 2002

69. Channel Slope
Particle Size

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