Appendix B: Bioengineering for Streambank Erosion Control -- Guidelines
1 Introduction
Background
Corps of Engineers (CE) and others are often restricted from using hard structures, such
as riprap or concrete lined channels, for streambank erosion control partly because of
environmental reasons and high cost. Within the last decade or so, increased demands have
been placed upon the CE by environmental agencies and others to incorporate vegetation into
their streambank erosion control projects rather than to rely completely on traditional
methods. Complete bank armorment by various methods such as riprapped revetment,
concrete revetment, bulkheads, concrete linings, etc. are considered by many to have little
value for fisheries, wildlife, water quality, and aesthetic appeal. Bioengineering, in contrast,
is receiving more emphasis from environmental agencies and conservation organizations.
Bioengineering is the combination of biological, mechanical, and ecological concepts to
control erosion and stabilize soil through the sole use of vegetation or in combination with
construction materials. Both living and non living plants can be used. Non-living plants are
used as construction materials, similar to engineered materials. The Planted vegetation
controls erosion and serves as good wildlife and fisheries habitat in riparian systems.
A limited number of streambank erosion control projects have been designed and
implemented by the CE where bioengineering has been purposely planned as a part of the
project. The CE has historically relied on construction projects with design lifes of 50 to 100
years that require a minimum amount of maintenance. Therefore, the focus of development
has been on hard structures that can be modeled and studied in hydraulic flumes and other test
structures and are designed to stay in place a long time. The CE has been reluctant to design
softer treatments, e.g., bioengineering, for erosion control because of a dearth of specific
design guidance. For instance, under what velocity conditions will certain vegetative
treatments work? This type of information has been slow to develop. In part, a lack of
monitoring after streambanks have been treated with a vegetative method has led to unknown
performance conditions and failure thresholds. In 1993, efforts were taken under the purview
of the Environmental Impact Research Program (EIRP), sponsored by Headquarters, US
Army Corps of Engineers, to develop and demonstrate bioengineering concepts for
streambank erosion control and to determine hydraulic velocities and conditions for successful
prototype performance and use.
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