Stream Dynamics, Inc.

 

Let the Water do the Work: Induced Meandering, an Evolving Method for Restoring Incised Channels

Like a moth emerging from its cocoon, an incised river can spread its wings by bursting its banks. How else can it create the space it needs to be free? If a river has become incised, either by short-term natural or unnatural causes, it will tend to evolve through a series of successional stages toward the long term predictable form reminiscent of the pre-disturbance type. Natural channel evolution proceeds sporadically and irregularly in response to random or stochastic events and is subject to reversals, a stuttering process at best.

Incised streams and gullies both perennial and ephemeral, are common throughout dryland regions of the American Southwest and the world. To what extent is the occurrence of incised channels related to human activity, what portion is natural? Downcutting can be unintended, deliberate or inadvertent as the direct or indirect result of human activity. Direct causes of downcutting include channelization and straightening for flood control, irrigation, agricultural and urban development, encroachment on river banks and floodplains by roads, railroads and pipelines, and by the concentration and acceleration of flows. Channel incision has also occurred throughout the southwest as the result of stream capture by low standard two-track roads, livestock trails and wagon roads.

Induced meandering is, at once, a science, an art and a philosophy of river restoration. It is an evolving method of converting incised channels occupying alluvial valley bottoms to a relatively non-incised condition by speeding up the natural process of channel evolution while removing some of the sporadic nature of the process.

As a science, induced meandering relies on the disciplines of geology, hydrology, fluvial geomorphology, biology and ecology for knowledge and guidance. As an Art, it strives to assist the stream in its career, using the power of floods to shape the channel and banks over time. Not all channels are appropriate candidates for Induced Meandering techniques, but the Induced Meandering philosophy of “going with the flow”, can inform all stream restoration projects. As a philosophy, induced meandering strives to understand rivers as timeless entities governed by immutable rules serving their watersheds, setting their own timetables, coping with their own realities as they carry mountains grain by grain to the sea. Rivers are to be treasured and respected, never bullied or coerced. What would life be if there were no rivers to sustain us?

This book has eight chapters, 239 pages and is illustrated with more than 100 photos, drawings, diagrams and graphics. Examples of successful treatments are described in sidebars to the main text.  Let the Water Do the Work contains annotated references, a glossary, an index and appendices that include field forms, worksheets and other tools for collecting and interpreting information pertinent to river and wetland restoration issues.

Chapter headings include:

• Introduction
• Reading the Landscape
• Basic Fluvial Geomorphology
• Induced Meandering Concepts: Actions, Reactions and Processes
• Structures and Practices
• Project Design and Implementation
• Monitoring, Modification and Maintenance

The book can be purchased from Amazon.com