Structures Help Rehabilitate Streambed Channels
July 24, 2001
Interlocking piles of felled trees
anchored to a streambed and adjacent banks can help protect eroding streambanks
and cost less than current control measures.
Many stream corridors in agricultural watersheds suffer from accelerated
erosion. For years, researchers have tried to stabilize streambanks with
planted vegetation. This technique is usually cheaper, better for the
environment and more aesthetically pleasing than traditional artificial control
measures that use structures made from costly stone and concrete. However,
vegetation is hard to establish in rapidly eroding channels.
Now, Agricultural Research Service
hydraulic engineer Doug Shields at the
Laboratory, Oxford, Miss.--in cooperation with the USDAs
Natural Resources Conservation Service,
U.S. Army Corps of Engineers
and local landowners--has designed and constructed an experimental erosion
control system. It uses interlocking piles of felled trees anchored to the
These felled-tree structures are designed to induce sediment deposition at
the toe--the place where the streambank intersects the streambed--of eroding
banks. This reverses erosion-driven channel enlargement. Data and observations
indicate that the structures create hydraulic conditions favorable to stream
habitat restoration and induce sediment to be deposited in areas formerly
subject to erosion.
About a year after construction, water depths near the structures had
doubled, reducing severe stress on the aquatic community caused by extremely
shallow conditions associated with channel erosion.
Additional components of the project include planting willow cuttings and
switchgrasses. Results could provide the technical basis for future
applications that cost only about one-third of current approaches featuring the
use of quarried stone and other artificial materials to stabilize streambanks.
This technology will help to create forested riparian buffer strips, control
streambank erosion and restore the nations 3.5 million miles of rivers
currently considered degraded by erosion, sedimentation and excess nutrients.
ARS is the U.S. Department of
Agricultures chief scientific research agency.