Environmental Features for Flood-Control Channels.
Abstract
This report presents and documents preliminary findings of an information review performed to develop environmental guidance for flood-control projects that involve modification of natural stream channels by clearing and snagging, alignment, enlargement, and lining. The response of the fluvial system to modification sometimes results in unintentional or unforeseen environmental impacts. In general, channel modification results in a shorter, smoother, more uniform channel with larger cross-sectional area and less natural vegetation. Overbank flooding is eliminated or reduced, and depths and velocities are changed at all flows. Since extreme channel instability has adverse effects on ecological and aesthetic resources, channel straightening should be minimized. The channel cross section should be designed for low as well as high flows; the existing velocity-versus-discharge relationship should be preserved as much as possible at low an intermediate flows to maintain the sediment transport characteristics of the existing channel. Environmental features have been found to have limited effectiveness unless the modified channel is reasonably stable, the project area is protected against further modification, and construction and maintenance work is closely supervised and inspected.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1982
- Accession Number
- ADA120544
Entities
People
- F. Douglas Shields Jr.