Impact of riverine wetlands construction and operation on stream channel stability: Conceptual framework for geomorphic assessment |
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Authors: | Bruce L Rhoads Michael V Miller |
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Institution: | (1) Department of Geography, University of Illinois, 61801 Urbana, Illinois, USA;(2) Illinois State Geological Survey, 61820 Champaign, Illinois, USA |
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Abstract: | Wetland conservation is a critical environmental management issue. An emerging approach to this issue involves the construction
of wetland environments. Because our understanding of wetlands function is incomplete and such projects must be monitored
closely because they may have unanticipated impacts on ecological, hydrological, and geomorphological systems. Assessment
of project-related impacts on stream channel stability is an important component of riverine wetlands construction and operation
because enhanced erosion or deposition associated with unstable rivers can lead to loss of property, reductions in channel
capacity, and degradation of water quality, aquatic habitat, and riparian aesthetics.
The water/sediment budget concept provides a scientific framework for evaluating the impact of riverine wetlands construction
and operation on stream channel stability. This concept is based on the principle of conservation of mass, i.e., the total
amount of water and sediment moving through a specific reach of river must be conserved. Long-term measurements of channel
sediment storage and other water/sediment budget components provide the basis for distinguishing between project-related impacts
and those resulting from other causes. Changes in channel sediment storage that occur as a result of changes in internal inputs
of water or sediment signal a project-related impact, whereas those associated with changes in upstream or tributary inputs
denote a change in environmental conditions elsewhere in the watershed. A geomorphic assessment program based on the water/sediment
budget concept has been implemented at the site of the Des Plaines River Wetlands Demonstration Projection near Chicago, Illinois,
USA. Channel sediment storage changed little during the initial construction phase, suggesting that thus far the project has
not affected stream channel stability. |
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Keywords: | Constructed wetlands Fluvial geomorphology Water/sediment budget |
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