This document provides an overview of fluvial geomorphology and channel classification methods. It discusses the connection between watershed processes, land, and water. Several classification systems are described for classifying stream channels, including the Rosgen and Montgomery-Buffington systems. Level 1 classification involves rapidly identifying stream type, while Level 2 classification uses field measurements of cross-sections, slope, sinuosity and other characteristics to further classify channels. Indicators of bankfull width are also outlined. The classification systems can be used to understand natural channel processes and impacts of disturbance.

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