|Shields f d jr,|
|Cooper c m,|
Submitted to: Journal of Hydraulic Engineering
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/14/1994
Publication Date: N/A
Citation: Interpretive Summary: Stream habitats and ecosystems are often severely damaged by accelerated erosion that follows watershed land use change and channelization. Low-cost techniques for restoring channel habitats are needed that can be integrated with existing channel erosion control technology. Aquatic habitats in a 1-km long reach of an erosion-damaged stream channel were partially restored by adding stone to existing stabilization works and planting willows as dormant posts, and results were monitored for two years. Restoration required only 10% more stone than orthodox stabilization. The overall size and shape of the channel was not affected, but the quality of stream and stream-side habitats improved significantly. A companion effort documented significant improvement in fish populations. Knowledge gained through this effort will be used by engineers in designing channel restoration measures for erosion-damaged streams.
Technical Abstract: Aquatic habitats in a 1-km reach of a deeply incised channel draining 91 km2 in northwest Mississippi were modified by adding stone and planting dormant willow posts. Restoration structures (groin extensions and longitudinal toe protection) required addition of only 10% more stone to existing channel stabilization works. During the year before restoration, baseflow aquatic habitats were characterized by uniform conditions, little woody debris or riparian vegetation, shallow depths, and sandy bed material. Gross channel geometry and bed material size were unaffected by restoration, but the average depth of scour holes adjacent to groins increased 53%, and pool habitat in the lower half of the study reach increased from 2.9% to 14% of water surface area within two years. Restoration structures improved bottom habitats by increasing the availability of submerged stone and cohesive sediments. Willow post planting increased woody vegetation cover on one side of the channel from 38% to 78% after two growing seasons. A companion study has documented significant, positive biological response to restoration.