The Rosgen Classification system developed by Dave Rosgen is easily the most widely applied river classification system used in the U.S. Its popularity is largely due to its codified nature, making it easy to learn for all levels of user within a limited amount of time (months) and money; and easy to apply uniformly (and repeat) across a range of natural systems. This exceptionally thorough and detailed classification scheme assigns a channel type based on channel slope, width to depth ratio, bed material, entrenchment ratio and sinuosity. Training is divided into four different levels of increasing detail. Ultimately, this method can be used to collect the raw data to assess mechanisms for predicting channel stability, erosion risk, aggradation, channel enlargement, sediment transport capacity, degradation, lateral or longitudinal migration, and hydraulic relations.
Significantly, the Rosgen system creates a framework for comparison between similar stream types.
The four levels of Rosgen method application include:
- Geomorphic Characterization
Input landform, lithology, soils, climate, depositional history, basin relief, valley morphology, river profile morphology, and general river pattern data to derive a letter stream classification type A through G.
- Morphological Description
Input channel patterns, entrenchment ratio, width to depth ratio, sinuosity, slope, and channel material to derive secondary (number) and tertiary (small letter with plus or minus) classification.
- Stream State/Condition (for Restoration Project Design)
Input information about the riparian vegetation, depositional patterns, meander patterns, confinement features, habitat indices, flow regime, river size category, debris presence/size, channel stability, bank erodability for application to a series of models and type curves that assess and predict stability, including: Modified Pfankuch Channel Stability Rating, BANCS: bank erosion, Sediment Competence and Entrainment capacity, FLOWSEDl: suspended and bedload sediment yield, POWERSED: change in transport rate, channel stability, and Channel Type Shift & Channel Stability Ratings.
- Verification (Restoration Project Assessment)
Direct measurement of sediment transport, erosion rates, aggradation, degradation processes, hydraulic geometry, biological data, etc. to assess success of a restoration project.
For more information a complete description and documentation, including training opportunities, please go to:
Rosgen, D. L., 1994. A classification of natural rivers. Catena, 22, 169-199
Rosgen, D.L., 2008. River Stability Field Guide. Wildland Hydrology, Fort Collins, CO. (available for purchase from Wildland Hydrology)
Rosgen, D.L., 2008. Watershed Assessment of River Stability and Sediment Supply. Wildland Hydrology, Fort Collins, CO. (available for purchase from Wildland Hydrology)
A response to many of the critiques of the Rosgen approach by the author can be found here:
Rosgen, D. L., 2006. The Application of Stream Classification Using the Fluvial Geomorphology Approach for Natural Channel Design: The Rest of the Story., 1-16
A thoughtful, balanced investigation of both sides of “The Rosgen Wars” is presented here:
Lave, Rebecca, 2009. The Controversy Over Natural Channel Design: Substantive Explanations and Potential Avenues for Resolution. Journal of the American Water Resources Association (JAWRA) 45(6):1519-1532. DOI:
Additional references for download from Wildland Hydrology