Restoration of Modified Channels
Many modified stream channels are described as being incised.
An Incised stream is defined as: a stream that has abandoned its previous foodplain due to the lowering of the stream bed and having high stream banks bounded by alluvial terraces.

A Successful Stream Restoration can be defined as: restoring the natural function, stability and biological condition of a stream.



Thousands of miles of Ohio streams have been modified, 'ditched', or channelized over the past 100 years for drainage purposes. This hydro-modification involves the deepening and straightening of stream channels and usually includes the complete removal of trees and substrate. The primary purpose of this "ditching" is to accommodate subsurface drainage or tile and convey water from point A to point B as quickly as possible.

As a result of this channelization, what were once highly productive and diverse headwater stream systems have simply become 'ditches'. The ditch shape and design is designed for drainage purposes only and is ecologically devastating to the natural function of streams. Because of this single use design, the fisheries and water quality in these streams degraded badly as documented by the regulatory agencies throughout the 1990's.

In 1983, the International Association of fish and Wildlife Agencies, the American Fisheries Society, US Forest Service, US Fish and Wildlife Service and many other organizations jointly produced a document that illustrated the negative affects of 'ditching', channelization and vegetation removal from stream channels. By 1994 the USACE developed an engineering manual that documented catastrophic consequences to channel stability from ditch practices involving deepening and straightening of stream channels.

Is there an alternative? Yes. Williams Leopold and many others have researched and developed stream classification systems based upon the documentation of predictable, morphological relationships in all streams. These classification systems have now been accepted across North America and can be properly addressed during the restoration of streams by implementing concepts known collectively as 'Natural Channel Design'.

One of the most important characteristics of Natural Channel Design is that stable, functional stream channels must have a floodplain. A second, equally important characteristic, is that of establishing healthy riparian and floodplain vegetation.

There are now formulas based on good science that can be used to calculate the stream-way widths and meander patterns within any given floodplain for Natural Channel Design. After the completion of a restoration process, there are also tools available for measuring the ability of the restored stream to support life, filter and assimilate pollutants, and remain geomorphically stable.

Unfortunately there is still much support for ditch construction. But, we now have the tools and knowledge to start restoring these ditches back to biologically functional streams.

We must all come to understand that 'streams are ecosystems and not just conveyance channels for water and sediment'. By incorporating Natural Channel Design into the process of restoring 'ditches' back into functional streams, we will be able to enjoy these natural ecosystems while simultaneously maintaining drainage and protecting infrastructure.

Natural Channel Design Concept implemented in Limited Project in Columbus Ohio; 2002. See Project spec. sheet here.

Attribute Comparison Between 'Ditching' and Stream Restoration
Attributes
Ditching
Stream Restoration
Based upon accepted geomorphic and NCD Principles
no
yes
Restores ecosystem values and function
no
yes
Restores floodplain, based upon stream-way concept
no
yes
Eliminates entrenched channel conditions
no
yes
Uses biological indicators in design and as satisfying criteria
no
yes
Restores use-attainment
no
yes
Is multi-disciplinary in design
no
yes
Meets multiple objectives, e.g. water quality, drainage, habitat
no
yes
Eliminates future maintenance costs
no
yes
Provides quantification of capacity, discharge and cost benefits
no
yes
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Oxbow River & Stream Restoration; 2905 Klondike Road; Delaware, OH 43015; (740) 362-4134.
© 2014 Oxbow River & Stream Restoration, Inc. Last updated January 2014.