Luna Leopold best describes Dave Rosgen's new book, Applied River Morphology, as "a generous and detailed explanation of the classification system and how it might be used to incorporate the observed processes of river mechanics into restoration design."

Applied River Morphology is the product of Dave Rosgen, a former hydrologist with the U.S. Forest Service and now Principal Hydrologist of Wildland Hydrology Consultants. The book is illustrated by Dave's long-time collaborator and former Forest Service Regional Hydrologist, Lee Silvey. Most of the volume describes in pictures and words the Rosgen stream classification system and lays out Rosgen's "natural stability" approach to stream restoration.

The classification system is based on Rosgen's 31 years of experience and observation of hundreds of natural, stable streams and rivers in North America. Building on geomorphological principles established by Luna Leopold and others, Rosgen observed a consistent pattern of natural river geometry and published a prototype classification system in 1985, followed by a revised and modified treatment of the subject in the geomorphological journal, Catena, in 1994. The book is essentially an expansion of the article, "A Classification of Natural Rivers," published in Catena.

Rosgen's system is based on the notion that the most effective classification system is one based on objective, quantifiable criteria that are readily observable and measurable in the field. The objective of classifying streams on the basis of channel morphology is to set categories of discrete stream types so that consistent, reproducible descriptions and assessments of condition and potential can be developed. Since the procedure relies on morphology, it is not readily apparent that the system is process based. However, the classification system is grounded in the basic morphological-process relations of fluvial systems.

The book begins with a brief discussion of fundamental principles of river systems followed by a discussion of stream classification and the hierarchy of river morphology. It then describes a four level hierarchy of river inventory and assessment including:

Level 1 - Geomorphic Characterization
Level 2 - Morphological Description
Level 3 - Assessment of Stream Condition and Departure from Potential
Level 4 - Field Data Verification.

Each of the levels is covered in detail with colorful illustrations, photographs, and examples fully explaining office and field methods (see example below).

The chapter on geomorphic characterization (Level 1) introduces some new concepts to the stream classification system by discussing the association between landforms and stream types. Eleven valley types describing valley morphology and their delineation criteria are introduced.

The largest part of the book is spent on morphological descriptions (Level 2), field methods for stream type delineation, and examples of stream types. Extensive photographs and illustrations of typical stream types (see below) are used to help the reader visualize the range of stream types (A, B, C, D, DA, E, F, and G) found in nature. Example field data forms to facilitate the process are included in the book.

Landform/soils:
Narrow, moderately steep colluvial valleys with gentle side slopes. Soils are colluvium and/or alluvium. Often in fault line valleys or on well vegetated alluvial fans.

Channel materials:
Predominantly cobble with lesser amounts of boulders, gravel and sand. Streambanks are stable due to coarse material.

Slope range: .02-.04 (B3c, <.02)

Width/depth ratio: >12

Entrenchment ratio: 1.4-2.2

Sinuosity: >1.2

The chapter on assessing stream condition and departure from potential (Level 3) will probably be the most controversial part of the book. Applying the classification describes only the existing morphologic condition. A given classification does not necessarily mean that the river is in a "stable" condition or functioning close to its "potential." Rosgen argues that the self-stabilization tendencies of a stream system and the natural tendency to evolve into a particular morphological form needs to be understood to provide a blueprint for the river's future. Several examples of evolutionary sequences are presented; however, the author cautions that these are only a few of many potential scenarios of stream type shifts that may occur.

The book ends with a discussion of applications of the classification system to solving real world problems. Field users of the classification system will find this book to be a constant and useful reference guide. Those looking for a scientific treatment of fluvial processes, stream classification and exposition of the data collected to derive the delineation parameters will be disappointed. The author presents summary frequency distribution data for the delineative criteria that make up the classification system, but not the raw data he measured over the years from the hundreds of channels observed throughout North America.

The book is primarily designed to permit interested users to understand the basis of the morphological hierarchy and to apply it in the field. The book fulfills this objective and will be a valuable addition to the library of anyone who needs to classify streams as part of their work on rivers.

Applied River Morphology is published by Wildland hydrology Books,157649 US HWY 160, Pagosa Spring, CO 81147; Phone: 970-264- 7100. The 390 page hard-cover book with 770 color illustrations and photographs sells for $89.95.