Approach to river classification

1. Fluvial Geomorphology and
Channel Classification
Watershed Condition Framework Application Workshop
Polyana, Ukraine
July 23-27, 2018
Sheela Johnson
Natural Resource Specialist, USDA Forest Service

2. Connection between land and water
Source: Maine Forest Service 2004
Watershed processes
& characteristics
Channel processes
& characteristics

3. Fluvial Geomorphology
• Definition: study of how flowing water shapes the
land through erosion and depositional processes.
• River classification methods are tools to understand
natural processes and the effects of disturbance
• Rosgen classification (Rosgen 1994)
• Mongtomery and Buffington classification (1993)
• Channel evolution model (Schumm et al 1984)
• Stream order (Horton 1945; Strahler 1957)

4. Sediment Balance
Sediment Load Stream Discharge
Source: Rosgen 1996

5. Sediment Balance
Sediment Decrease or
Water Flow Increase
Sediment Increase or
Water Flow Decrease
Source: Rosgen 1996
EROSION DEPOSITION

6. Level 1 Classification: Rapidly Identify Stream Type
Source: US EPA,
https://cfpub.epa.gov/watertrain/moduleFrame.cfm?parent_object_id=1189

7. Level 1: broad scale classification

8. Level 2 Classification: Field
Measurements
• Cross-Section
Measurements:
• Bankfull depth and width
• Floodprone width
• Bed material
• Entrenchment ratio
• Width-Depth ratio
• Reach measurements:
• Slope
• Bed features
• Sinuosity
• Meander width ratio
Wildland Hydrology

9. www.fs.fed.us
Channel Evaluation
floodplain
bankfull
Valley type
Bed and bank
material

10. Bankfull Width Indicators:
understanding the forces that shape channels
• Flat depositional benches
• Change in bank from steep to more
gentle slope
• Nearly flat top of point bars
• Lower extent of non-wetland woody
vegetation*
• Erosion or scour features*
• *Use with care or in conjunction with
other indicators
http://feh.iupui.edu/tools/determining-bankfull-stage/field-indicators-
of-bankfull-stage/gallery/

11. Bankfull Width Indicators:
understanding the forces that shape channels
• Flat depositional benches
• Change in bank from steep to more
gentle slope
• Nearly flat top of point bars
• Lower extent of non-wetland woody
vegetation*
• Erosion or scour features*
*Use with care or in conjunction with other
indicators
From Vermont Agency of Natural Resources, 2009. “Vermont Stream Geomorphic Assessment”

12. Width to Depth Ratio
Sources: Cuyahogaswcd.org,
https://www.como.gov/utilities/stormwater-engineering/319-grant/step-pool/
Understanding width to depth ratio can help you predict the future

13. Entrenchment
Source: U.S. EPA, Rosgen 1996

14. Sinuosity
Source: U.S. EPA

15. Slope
Source: Rosgen 1996

16. Level 2 Classification Summary
Source: Rosgen 1996

17. Level 2 Classification Summary
More details = more stream types
Entrenchment
Width – depth ratio
Sinuosity
Water slope
Source:
Rosgen 1996

18. Improperly
designed stream
crossings:
• scouring
• downcutting
• widening
Application: stream crossing

19. APPROACH A-OUTSIDE
THE BUFFER
APPROACH A-
INSIDE THE
BUFFER
CROSSING
STRUCTURE
STREAM
CHANNEL
Application:
Forestry Best Management Practices

20. References and additional information
• Rosgen, D.L. and H.L. Silvey. 1996. Applied River
Morphology. Wildland Hydrology Books, Fort
Collins, CO
• US EPA Watershed Academy Web, Fundamentals of
Rosgen Stream Classification System
https://cfpub.epa.gov/watertrain/moduleFrame.cfm
?parent_object_id=1189