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Approaches: The Nature of Stream Restoration |
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Contrary too much of the current discussion, stream restoration is more than just creating a "correct" channel morphology or using the "rock-weir-of-the-day". Streams ecosystems function at very different levels - hydraulically and biologically within various constraints or impacts such as urbanization or channelization. Understanding how these various components function as an ecosystem provides the foundation for the restoration process, which allows the stream to do much of the restoration work with natural trends and processes. There is some debate over just how much detail is needed in a restoration design to adequately facilitate recovery - and how quickly that recovery needs to occur. Some believe that by simply protecting or acquiring a width of buffer adjacent to an impacted stream is adequate to allow it to naturally evolve to the highest potential. These issues beg the question, where is the biggest bang for the buck during this process? The restoration of stream ecosystems starts with a basic understanding of fluvial processes - the physical principles and relationships from which healthy stream ecosystems evolve. Natural Channel Design (NCD) as a tool in the restoration process, works well in environments that have natural watersheds and hydrologic regimes. The very basis for NCD is the empirical relationships between the catchment area and the receiving channel. These are very broad relationships at a very large temporal scale. However, simply applying the shape of a great looking natural stream channel in an urban environment can spell disaster. Urban and modified watersheds require additional consideration at that scale and more importantly, attention to detail at the smallest temporal scale to provide a solid foundation for ecosystem recovery. Stream ecosystems are much more than geomorphic relationships and the riparian area is more that a simplistic calculation of belt width, meander pattern and watershed size. The riparian area is an ecosystem unto itself, which supports the most diverse and dense flora and fauna populations in the landscape. The most common stream types, using the Rosgen Stream Classification, are very dependent upon a mature vegetated riparian zone to maintain a stable, and therefore functional, channel shape. Without that riparian vegetation, the channel shape itself will slowly self-destruct by means of entrenchment, braiding, or widening. From an understanding of the watershed hydrology to the critical flows of a riffle, stream restoration requires many important considerations across a broad temporal scale to provide a foundation for ecosystem recovery. 
Geomorphology - the hydrology of the watershed determines the shape and size of the channel and it's relationship to the floodplain within the valley |
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Oxbow River & Stream Restoration; 2905 Klondike Road; Delaware, OH 43015; (740) 362-4134. © 2008 Oxbow River & Stream Restoration, Inc. Last updated July-2008. |
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