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|Title:||Review of environmental consequences of waterway design and construction practices as of 1979|
Environmental and Water Quality Operational Studies (U.S.)
Thackston, Edward L.
Sneed, Robert B.
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: Waterway projects designed and constructed by the Corps of Engineers (CE) include dikes, revetments, levees, and channel modifications for flood control and navigation purposes. A review of existing CE design guidance in the form of Engineer Manuals (EMs) and personal contacts with CE field offices was performed to appraise current practices regarding consideration of environmental effects in the design and construction of waterway projects. A computer-assisted review of the technical literature was also performed in order to determine observed adverse environmental effects of waterway projects. Possible adverse effects presented in the literature included wetlands drainage, loss of native vegetation, cutoff of oxbows and meanders, water table drawdown, increased erosion and sedimentation, and change of aesthetics. Other possible effects on the aquatic system may include the loss of aquatic habitat, productivity, and species diversity, and the degradation of water quality. Alternatives to traditional channel modification were identified through the literature review. Structural alternatives to channel modification include levees, floodways , reservoirs, and land treatment measures. Additional alternatives include various forms of floodplain management; floodplain zoning; construction of bypass channels around sensitive wetland areas; construction of numerous, very small, water-retention structures ; and substitution of clearing and snagging, or only snagging , for complete channelization. Current efforts to minimize adverse environmental effects of dikes were investigated through personal contact with CE field offices. Programs of notching or gapping dikes are in progress on the Missouri and Mississippi Rivers. Studies are under way to quantify the effects of such notches on the riverine ecosystem. Case studies of the planning process are presented for two recently designed waterway projects.
|Appears in Collections:||Technical Report|